HA scale-up cluster configuration guide for SAP HANA on SLES

This guide shows you how to deploy and configure a performance-optimized SUSE Linux Enterprise Server (SLES) high-availability (HA) cluster for an SAP HANA scale-up system on Google Cloud.

This guide includes the steps for:

• Configuring an internal passthrough Network Load Balancer to reroute traffic in the event of a failure
• Configuring a Pacemaker cluster on SLES to manage the SAP systems and other resources during a failover

This guide also includes steps for configuring SAP HANA system replication, but refer to the SAP documentation for the definitive instructions.

To deploy a SAP HANA system without a Linux high-availability cluster or a standby node host, use the SAP HANA deployment guide.

To configure an HA cluster for SAP HANA on Red Hat Enterprise Linux (RHEL), see the HA cluster configuration guide for SAP HANA scale-up on RHEL.

This guide is intended for advanced SAP HANA users who are familiar with Linux high-availability configurations for SAP HANA.

The system that this guide deploys

Following this guide, you will deploy two SAP HANA instances and set up an HA cluster on SLES. You deploy each SAP HANA instance on a Compute Engine VM in a different zone within the same region. A high-availability installation of SAP NetWeaver is not covered in this guide.

The deployed cluster includes the following functions and features:

• Two host VMs, each with an instance of SAP HANA
• Synchronous SAP HANA system replication.
• The Pacemaker high-availability cluster resource manager.
• A STONITH fencing mechanism.
• Automatic restart of the failed instance as the new secondary instance.

This guide has you use the Cloud Deployment Manager templates that are provided by Google Cloud to deploy the Compute Engine virtual machines (VMs) and the SAP HANA instances, which ensures that the VMs and the base SAP HANA systems meet SAP supportability requirements and conform to current best practices.

SAP HANA Studio is used in this guide to test SAP HANA system replication. You can use SAP HANA Cockpit instead, if you prefer. For information about installing SAP HANA Studio, see:

• Installing SAP HANA Studio on a Compute Engine Windows VM
• SAP HANA Studio Installation and Update Guide

Prerequisites

Before you create the SAP HANA high availability cluster, make sure that the following prerequisites are met:

• You have read the SAP HANA planning guide and the SAP HANA high-availability planning guide.
• You or your organization has a Google Cloud account and you have created a project for the SAP HANA deployment. For information about creating Google Cloud accounts and projects, see Setting up your Google account in the SAP HANA Deployment Guide.
• If you require your SAP workload to run in compliance with data residency, access control, support personnel, or regulatory requirements, then you must create the required Assured Workloads folder. For more information, see Compliance and sovereign controls for SAP on Google Cloud.

• The SAP HANA installation media is stored in a Cloud Storage bucket that is available in your deployment project and region. For information about how to upload SAP HANA installation media to a Cloud Storage bucket, see Downloading SAP HANA in the SAP HANA Deployment Guide.

• If OS login is enabled in your project metadata, you need to disable OS login temporarily until your deployment is complete. For deployment purposes, this procedure configures SSH keys in instance metadata. When OS login is enabled, metadata-based SSH key configurations are disabled, and this deployment fails. After deployment is complete, you can enable OS login again.

  For more information, see:

  • Enabling or disabling OS Login
  • Add SSH keys to VMs that use metadata-based SSH keys

• If you are using VPC internal DNS, the value of the vmDnsSetting variable in your project metadata must be either GlobalOnly or ZonalPreferred to enable the resolution of the node names across zones. The default setting of vmDnsSetting is ZonalOnly. For more information, see:

  • Configuring DNS names for your project or instances
  • Querying custom metadata
  • Setting project-wide custom metadata

To avoid unintentionally exposing your VM instance to the internet, follow these recommendations:

• Use a NAT gateway.
• Create firewall rules that block all external access that you don't require.
• When you create your VMs:
  • Specify a network tag for each VM for use in routing and firewall rules. If you use the Deployment Manager template that Google Cloud provides, specify a tag with networkTag: [TAG].
  • Create the VMs without an external IP. If you use the Deployment Manager templates that Google Cloud provides, specify publicIP: No.

Creating a network

For security purposes, create a new network. You can control who has access by adding firewall rules or by using another access control method.

If your project has a default VPC network, don't use it. Instead, create your own VPC network so that the only firewall rules in effect are those that you create explicitly.

During deployment, VM instances typically require access to the internet to download Google Cloud's Agent for SAP. If you are using one of the SAP-certified Linux images that are available from Google Cloud, the VM instance also requires access to the internet in order to register the license and to access OS vendor repositories. A configuration with a NAT gateway and with VM network tags supports this access, even if the target VMs do not have external IPs.

To set up networking:

Console

1. In the Google Cloud console, go to the VPC networks page.

   Go to VPC networks

2. Click Create VPC network.
3. Enter a Name for the network.

   The name must adhere to the naming convention. VPC networks use the Compute Engine naming convention.

4. For Subnet creation mode, choose Custom.
5. In the New subnet section, specify the following configuration parameters for a subnet:
   1. Enter a Name for the subnet.
   2. For Region, select the Compute Engine region where you want to create the subnet.
   3. For IP stack type, select IPv4 (single-stack) and then enter an IP address range in the CIDR format, such as 10.1.0.0/24.

      This is the primary IPv4 range for the subnet. If you plan to add more than one subnet, then assign non-overlapping CIDR IP ranges for each subnetwork in the network. Note that each subnetwork and its internal IP ranges are mapped to a single region.

   4. Click Done.
6. To add more subnets, click Add subnet and repeat the preceding steps. You can add more subnets to the network after you have created the network.
7. Click Create.

gcloud

1. Go to Cloud Shell.

   Go to Cloud Shell

2. To create a new network in the custom subnetworks mode, run:

   gcloud compute networks create NETWORK_NAME --subnet-mode custom

   Replace NETWORK_NAME with the name of the new network. The name must adhere to the naming convention. VPC networks use the Compute Engine naming convention.

   Specify --subnet-mode custom to avoid using the default auto mode, which automatically creates a subnet in each Compute Engine region. For more information, see Subnet creation mode.

3. Create a subnetwork, and specify the region and IP range:

   gcloud compute networks subnets create SUBNETWORK_NAME \
       --network NETWORK_NAME --region REGION --range RANGE

   Replace the following:

   • SUBNETWORK_NAME: the name of the new subnetwork
   • NETWORK_NAME: the name of the network you created in the previous step
   • REGION: the region where you want the subnetwork
   • RANGE: the IP address range, specified in CIDR format, such as 10.1.0.0/24

     If you plan to add more than one subnetwork, assign non-overlapping CIDR IP ranges for each subnetwork in the network. Note that each subnetwork and its internal IP ranges are mapped to a single region.

4. Optionally, repeat the previous step and add additional subnetworks.

Setting up a NAT gateway

If you need to create one or more VMs without public IP addresses, you need to use network address translation (NAT) to enable the VMs to access the internet. Use Cloud NAT, a Google Cloud distributed, software-defined managed service that lets VMs send outbound packets to the internet and receive any corresponding established inbound response packets. Alternatively, you can set up a separate VM as a NAT gateway.

Key Point: When you configure Cloud NAT, specify at least 160 as the minimum number of ports per VM. Certain operating system updates run concurrent processes that might exceed the Cloud NAT default for the number of ports, which can result in activation or download errors.

When you create a Cloud NAT instance, specify the number of ports in the Minimum ports per VM field under Advanced configurations on the Create a NAT gateway page in the Google Cloud console.

To create a Cloud NAT instance for your project, see Using Cloud NAT.

After you configure Cloud NAT for your project, your VM instances can securely access the internet without a public IP address.

Adding firewall rules

By default, an implied firewall rule blocks incoming connections from outside your Virtual Private Cloud (VPC) network. To allow incoming connections, set up a firewall rule for your VM. After an incoming connection is established with a VM, traffic is permitted in both directions over that connection.

You can also create a firewall rule to allow external access to specified ports, or to restrict access between VMs on the same network. If the default VPC network type is used, some additional default rules also apply, such as the default-allow-internal rule, which allows connectivity between VMs on the same network on all ports.

Depending on the IT policy that is applicable to your environment, you might need to isolate or otherwise restrict connectivity to your database host, which you can do by creating firewall rules.

Depending on your scenario, you can create firewall rules to allow access for:

• The default SAP ports that are listed in TCP/IP of All SAP Products.
• Connections from your computer or your corporate network environment to your Compute Engine VM instance. If you are unsure of what IP address to use, talk to your company's network administrator.
• Communication between VMs in the SAP HANA subnetwork, including communication between nodes in an SAP HANA scale-out system or communication between the database server and application servers in a 3-tier architecture. You can enable communication between VMs by creating a firewall rule to allow traffic that originates from within the subnetwork.

Note: The following procedure is a simplified version of the instructions for creating firewall rules. For more detailed instructions, see Creating firewall rules.

To create a firewall rule:

Console

1. In the Google Cloud console, go to the VPC network Firewall page.

   Go to Firewall

2. At the top of the page, click Create firewall rule.

   • In the Network field, select the network where your VM is located.
   • In the Targets field, specify the resources on Google Cloud that this rule applies to. For example, specify All instances in the network. Or to to limit the rule to specific instances on Google Cloud, enter tags in Specified target tags.
   • In the Source filter field, select one of the following:
     • IP ranges to allow incoming traffic from specific IP addresses. Specify the range of IP addresses in the Source IP ranges field.
     • Subnets to allow incoming traffic from a particular subnetwork. Specify the subnetwork name in the following Subnets field. You can use this option to allow access between the VMs in a 3-tier or scaleout configuration.
   • In the Protocols and ports section, select Specified protocols and ports and enter tcp:PORT_NUMBER.

3. Click Create to create your firewall rule.

gcloud

Create a firewall rule by using the following command:

$ gcloud compute firewall-rules create FIREWALL_NAME
--direction=INGRESS --priority=1000 \
--network=NETWORK_NAME --action=ALLOW --rules=PROTOCOL:PORT \
--source-ranges IP_RANGE --target-tags=NETWORK_TAGS

Deploying the VMs and SAP HANA

Before you begin configuring the HA cluster, you define and deploy the VM instances and SAP HANA systems that serve as the primary and secondary nodes in your HA cluster.

To define and deploy the systems, you use the same Cloud Deployment Manager template that you use to deploy a SAP HANA system in the SAP HANA deployment guide.

However, to deploy two systems instead of one, you need to add the definition for the second system to the configuration file by copying and pasting the definition of the first system. After you create the second definition, you need to change the resource and instance names in the second definition. To protect against a zonal failure, specify a different zone in the same region. All other property values in the two definitions stay the same.

After the SAP HANA systems have deployed successfully, you define and configure the HA cluster.

The following instructions use the Cloud Shell, but are generally applicable to the Google Cloud CLI.

1. Confirm that your current quotas for resources such as persistent disks and CPUs are sufficient for the SAP HANA systems you are about to install. If your quotas are insufficient, deployment fails. For the SAP HANA quota requirements, see Pricing and quota considerations for SAP HANA.

   Go to the quotas page

2. Open the Cloud Shell or, if you installed the gcloud CLI on your local workstation, open a terminal.

   Go to the Cloud Shell

3. Download the template.yaml configuration file template for the SAP HANA high-availability cluster to your working directory by entering the following command in the Cloud Shell or gcloud CLI:

   wget https://storage.googleapis.com/cloudsapdeploy/deploymentmanager/latest/dm-templates/sap_hana/template.yaml

4. Optionally, rename the template.yaml file to identify the configuration it defines.

5. Open the template.yaml file in the Cloud Shell code editor or, if you are using the gcloud CLI, the text editor of your choice.

   To open the Cloud Shell code editor, click the pencil icon in the upper right corner of the Cloud Shell terminal window.

6. In the template.yaml file, complete the definition of the primary SAP HANA system. Specify the property values by replacing the brackets and their contents with the values for your installation. The properties are described in the following table.

   To create the VM instances without installing SAP HANA, delete or comment out all of the lines that begin with sap_hana_.

   Property	Data type	Description
   type	String	Specifies the location, type, and version of the Deployment Manager template to use during deployment. The YAML file includes two type specifications, one of which is commented out. The type specification that is active by default specifies the template version as latest. The type specification that is commented out specifies a specific template version with a timestamp. If you need all of your deployments to use the same template version, use the type specification that includes the timestamp.
   instanceName	String	The name of the VM instance currently being defined. Specify different names in the primary and secondary VM definitions. Names must be specified in lowercase letters, numbers, or hyphens.
   instanceType	String	The type of Compute Engine virtual machine that you need to run SAP HANA on. If you need a custom VM type, specify a predefined VM type with a number of vCPUs that is closest to the number you need while still being larger. After deployment is complete, modify the number of vCPUs and the amount of memory .
   zone	String	The Google Cloud zone in which to deploy the VM instance that your are defining. Specify different zones in the same region for the primary and secondary HANA definitions. The zones must be in the same region that you selected for your subnet.
   subnetwork	String	The name of the subnetwork you created in a previous step. If you are deploying to a shared VPC, specify this value as [SHAREDVPC_PROJECT]/[SUBNETWORK]. For example, myproject/network1.
   linuxImage	String	The name of the Linux operating-system image or image family that you are using with SAP HANA. To specify an image family, add the prefix family/ to the family name. For example, family/sles-15-sp1-sap. To specify a specific image, specify only the image name. For the list of available images and families, see the Images page in Google Cloud console.
   linuxImageProject	String	The Google Cloud project that contains the image you are going to use. This project might be your own project or a Google Cloud image project, such as suse-sap-cloud. For more information about Google Cloud image projects, see the Images page in the Compute Engine documentation.
   sap_hana_deployment_bucket	String	The name of the Google Cloud storage bucket in your project that contains the SAP HANA installation and revision files that you uploaded in a previous step. Any upgrade revision files in the bucket are applied to SAP HANA during the deployment process.
   sap_hana_sid	String	The SAP HANA system ID (SID). The ID must consist of three alphanumeric characters and begin with a letter. All letters must be uppercase.
   sap_hana_instance_number	Integer	The instance number, 0 to 99, of the SAP HANA system. The default is 0.
   sap_hana_sidadm_password	String	The password for the operating system (OS) administrator. Passwords must be at least eight characters and include at least one uppercase letter, one lowercase letter, and one number. Caution: Change the password after the installation is complete.
   sap_hana_system_password	String	The password for the database superuser. Passwords must be at least 8 characters and include at least one uppercase letter, one lowercase letter, and one number. Caution: Change the password after the installation is complete.
   sap_hana_sidadm_uid	Integer	The default value for the SID_LCadm user ID is 900 to avoid user-created groups conflicting with SAP HANA. You can change this to a different value if you need to.
   sap_hana_sapsys_gid	Integer	The default group ID for sapsys is 79. By specifying a value above you can override this value to your requirements.
   sap_hana_scaleout_nodes	Integer	Specify 0. These instructions are for scale-up SAP HANA systems only.
   networkTag	String	A network tag that represents your VM instance for firewall or routing purposes. If you specify publicIP: No and do not specify a network tag, be sure to provide another means of access to the internet.
   nic_type	String	Optional but recommended if available for the target machine and OS version. Specifies the network interface to use with the VM instance. You can specify the value GVNIC or VIRTIO_NET. To use a Google Virtual NIC (gVNIC), you need to specify an OS image that supports gVNIC as the value for the linuxImage property. For the OS image list, see Operating system details. If you do not specify a value for this property, then the network interface is automatically selected based on the machine type that you specify for the instanceType property. This argument is available in Deployment Manager template versions 202302060649 or later.
   publicIP	Boolean	Optional. Determines whether a public IP address is added to your VM instance. The default is Yes. Note: Do not specify No unless you have a NAT gateway configured with a network tag defined for the VM or you have provided the VM with another route to the internet. If there is no route to the internet, the installation fails.
   serviceAccount	String	Optional. Specifies a service account to be used by the host VMs and by the programs that run on the host VMs. Specify the email address of the service account. For example, [e-mail]. By default, the Compute Engine default service account is used. For more information, see Identity and access management for SAP programs on Google Cloud.

7. Create the definition of the secondary SAP HANA system by copying the definition of the primary SAP HANA system and pasting the copy after the primary SAP HANA system definition. See the example following these steps.

8. In the definition of the secondary SAP HANA system, specify different values for the following properties than you specified in the primary SAP HANA system definition:

   • name
   • instanceName
   • zone

9. Create the instances:

   gcloud deployment-manager deployments create DEPLOYMENT_NAME --config TEMPLATE_NAME.yaml

   The above command invokes the Deployment Manager, which deploys the VMs, downloads the SAP HANA software from your storage bucket, and installs SAP HANA, all according to the specifications in your template.yaml file.

   Deployment processing consists of two stages. In the first stage, Deployment Manager writes its status to the console. In the second stage, the deployment scripts write their status to Cloud Logging.

Example of a complete template.yaml configuration file

The following example shows a completed template.yaml configuration file that deploys two VM instances with a SAP HANA system installed.

The file contains the definitions of two resources to deploy: sap_hana_primary and sap_hana_secondary. Each resource definition contains the definitions for a VM and a SAP HANA instance.

The sap_hana_secondary resource definition was created by copying and pasting the first definition, and then modifying the values of name, instanceName, and zone properties. All other property values in the two resource definitions are the same.

The properties networkTag, serviceAccount, sap_hana_sidadm_uid, and sap_hana_sapsys_gid are from the Advanced Options section of the configuration file template. The properties sap_hana_sidadm_uid and sap_hana_sapsys_gid are included to show their default values, which are used because the properties are commented out.

resources:
- name: sap_hana_primary
  type: https://storage.googleapis.com/cloudsapdeploy/deploymentmanager/latest/dm-templates/sap_hana/sap_hana.py
  #
  # By default, this configuration file uses the latest release of the deployment
  # scripts for SAP on Google Cloud.  To fix your deployments to a specific release
  # of the scripts, comment out the type property above and uncomment the type property below.
  #
  # type: https://storage.googleapis.com/cloudsapdeploy/deploymentmanager/yyyymmddhhmm/dm-templates/sap_hana/sap_hana.py
  #
  properties:
    instanceName: hana-ha-vm-1
    instanceType: n2-highmem-32
    zone: us-central1-a
    subnetwork: example-subnet-us-central1
    linuxImage: family/sles-15-sp1-sap
    linuxImageProject: suse-sap-cloud
    sap_hana_deployment_bucket: hana2-sp4-rev46
    sap_hana_sid: HA1
    sap_hana_instance_number: 22
    sap_hana_sidadm_password: Tempa55word
    sap_hana_system_password: Tempa55word
    sap_hana_scaleout_nodes: 0
    networkTag: cluster-ntwk-tag
    serviceAccount: [e-mail]
    # sap_hana_sidadm_uid: 900
    # sap_hana_sapsys_gid: 79

- name: sap_hana_secondary
  type: https://storage.googleapis.com/cloudsapdeploy/deploymentmanager/latest/dm-templates/sap_hana/sap_hana.py
  #
  # By default, this configuration file uses the latest release of the deployment
  # scripts for SAP on Google Cloud.  To fix your deployments to a specific release
  # of the scripts, comment out the type property above and uncomment the type property below.
  #
  # type: https://storage.googleapis.com/cloudsapdeploy/deploymentmanager/yyyymmddhhmm/dm-templates/sap_hana/sap_hana.py
  #
  properties:
    instanceName: hana-ha-vm-2
    instanceType: n2-highmem-32
    zone: us-central1-c
    subnetwork: example-subnet-us-central1
    linuxImage: family/sles-15-sp1-sap
    linuxImageProject: suse-sap-cloud
    sap_hana_deployment_bucket: hana2-sp4-rev46
    sap_hana_sid: HA1
    sap_hana_instance_number: 22
    sap_hana_sidadm_password: Google123
    sap_hana_system_password: Google123
    sap_hana_scaleout_nodes: 0
    networkTag: cluster-ntwk-tag
    serviceAccount: [e-mail]
    # sap_hana_sidadm_uid: 900
    # sap_hana_sapsys_gid: 79
    

Create firewall rules that allow access to the host VMs

If you haven't done so already, create firewall rules that allow access to each host VM from the following sources:

• For configuration purposes, your local workstation, a bastion host, or a jump server
• For access between the cluster nodes, the other host VMs in the HA cluster

When you create VPC firewall rules, you specify the network tags that you defined in the template.yaml configuration file to designate your host VMs as the target for the rule.

To verify deployment, define a rule to allow SSH connections on port 22 from a bastion host or your local workstation.

For access between the cluster nodes, add a firewall rule that allows all connection types on any port from other VMs in the same subnetwork.

Make sure that the firewall rules for verifying deployment and for intra-cluster communication are created before proceeding to the next section. For instructions, see Adding firewall rules.

Verifying the deployment of the VMs and SAP HANA

To verify deployment, you check the deployment logs in Cloud Logging and check the disks and services on the VMs of primary and secondary hosts.

1. In the Google Cloud console, open Cloud Logging to monitor installation progress and check for errors.

   Note: You might incur costs when completing this step in Cloud Logging. For more information, see Cloud Logging pricing.

   Go to Cloud Logging

2. Filter the logs:

   Logs Explorer

   1. In the Logs Explorer page, go to the Query pane.

   2. From the Resource drop-down menu, select Global, and then click Add.

      If you don't see the Global option, then in the query editor, enter the following query:

      resource.type="global"
      "Deployment"
      

   3. Click Run query.

   Legacy Logs Viewer

   • In the Legacy Logs Viewer page, from the basic selector menu, select Global as your logging resource.

3. Analyze the filtered logs:

   • If "--- Finished" is displayed, then the deployment processing is complete and you can proceed to the next step.

   • If you see a quota error:

     1. On the IAM & Admin Quotas page, increase any of your quotas that do not meet the SAP HANA requirements that are listed in the SAP HANA planning guide.

     2. On the Deployment Manager Deployments page, delete the deployment to clean up the VMs and persistent disks from the failed installation.

     3. Rerun your deployment.

Check the configuration of the VMs and SAP HANA

1. After the SAP HANA system deploys without errors, connect to each VM by using SSH. From the Compute Engine VM instances page, you can click the SSH button for each VM instance, or you can use your preferred SSH method.

   

2. Change to the root user.

   $ sudo su -

3. At the command prompt, enter df -h. On each VM, ensure that you see the /hana directories, such as /hana/data.

   Filesystem                        Size  Used Avail Use% Mounted on
   /dev/sda2                          30G  4.0G   26G  14% /
   devtmpfs                          126G     0  126G   0% /dev
   tmpfs                             126G     0  126G   0% /dev/shm
   tmpfs                             126G   17M  126G   1% /run
   tmpfs                             126G     0  126G   0% /sys/fs/cgroup
   /dev/sda1                         200M  9.7M  191M   5% /boot/efi
   /dev/mapper/vg_hana-shared        251G   49G  203G  20% /hana/shared
   /dev/mapper/vg_hana-sap            32G  240M   32G   1% /usr/sap
   /dev/mapper/vg_hana-data          426G  7.0G  419G   2% /hana/data
   /dev/mapper/vg_hana-log           125G  4.2G  121G   4% /hana/log
   /dev/mapper/vg_hanabackup-backup  512G   33M  512G   1% /hanabackup
   tmpfs                              26G     0   26G   0% /run/user/900
   tmpfs                              26G     0   26G   0% /run/user/899
   tmpfs                              26G     0   26G   0% /run/user/1000

4. Change to the SAP admin user by replacing SID_LC in the following command with the system ID that you specified in the configuration file template. Use lowercase for any letters.

   # su - SID_LCadm

5. Ensure that the SAP HANA services, such as hdbnameserver, hdbindexserver, and others, are running on the instance by entering the following command:

   > HDB info

6. If you are using RHEL for SAP 9.0 or later, then make sure that the packages chkconfig and compat-openssl11 are installed on your VM instance.

   For more information from SAP, see SAP Note 3108316 - Red Hat Enterprise Linux 9.x: Installation and Configuration .

Validate your installation of Google Cloud's Agent for SAP

After you have deployed a VM and installed your SAP system, validate that Google Cloud's Agent for SAP is functioning properly.

Verify that Google Cloud's Agent for SAP is running

To verify that the agent is running, follow these steps:

1. Establish an SSH connection with your Compute Engine instance.

2. Run the following command:

   systemctl status google-cloud-sap-agent

   If the agent is functioning properly, then the output contains active (running). For example:

   google-cloud-sap-agent.service - Google Cloud Agent for SAP
   Loaded: loaded (/usr/lib/systemd/system/google-cloud-sap-agent.service; enabled; vendor preset: disabled)
   Active:  active (running)  since Fri 2022-12-02 07:21:42 UTC; 4 days ago
   Main PID: 1337673 (google-cloud-sa)
   Tasks: 9 (limit: 100427)
   Memory: 22.4 M (max: 1.0G limit: 1.0G)
   CGroup: /system.slice/google-cloud-sap-agent.service
          └─1337673 /usr/bin/google-cloud-sap-agent
   

If the agent isn't running, then restart the agent.

Verify that SAP Host Agent is receiving metrics

To verify that the infrastructure metrics are collected by Google Cloud's Agent for SAP and sent correctly to the SAP Host Agent, follow these steps:

1. In your SAP system, enter transaction ST06.

2. In the overview pane, check the availability and content of the following fields for the correct end-to-end setup of the SAP and Google monitoring infrastructure:

   • Cloud Provider: Google Cloud Platform
   • Enhanced Monitoring Access: TRUE
   • Enhanced Monitoring Details: ACTIVE

Set up monitoring for SAP HANA

Optionally, you can monitor your SAP HANA instances using Google Cloud's Agent for SAP. From version 2.0, you can configure the agent to collect the SAP HANA monitoring metrics and send them to Cloud Monitoring. Cloud Monitoring lets you create dashboards to visualize these metrics, set up alerts based on metric thresholds, and more.

For more information about the collection of SAP HANA monitoring metrics using Google Cloud's Agent for SAP, see SAP HANA monitoring metrics collection.

Disable SAP HANA autostart

For each SAP HANA instance in the cluster, make sure that SAP HANA autostart is disabled. For failovers, Pacemaker manages the starting and stopping of the SAP HANA instances in a cluster.

1. On each host as SID_LCadm, stop SAP HANA:

   > HDB stop

2. On each host, open the SAP HANA profile by using an editor, such as vi:

   vi /usr/sap/SID/SYS/profile/SID_HDBINST_NUM_HOST_NAME

3. Set the Autostart property to 0:

   Autostart=0

4. Save the profile.

5. On each host as SID_LCadm, start SAP HANA:

   > HDB start

Enable SAP HANA Fast Restart

Google Cloud strongly recommends enabling SAP HANA Fast Restart for each instance of SAP HANA, especially for larger instances. SAP HANA Fast Restart reduces restart time in the event that SAP HANA terminates, but the operating system remains running.

Note: If you deploy SAP HANA using Google Cloud's Terraform module sap_hana or sap_hana_ha, version 202309280828 or later, then fast restart is automatically enabled.

As configured by the automation scripts that Google Cloud provides, the operating system and kernel settings already support SAP HANA Fast Restart. You need to define the tmpfs file system and configure SAP HANA.

To define the tmpfs file system and configure SAP HANA, you can follow the manual steps or use the automation script that Google Cloud provides to enable SAP HANA Fast Restart. For more information, see:

• Manual steps: Enable SAP HANA Fast Restart
• Automated steps: Enable SAP HANA Fast Restart

For the complete authoritative instructions for SAP HANA Fast Restart, see the SAP HANA Fast Restart Option documentation.

Manual steps

Configure the tmpfs file system

After the host VMs and the base SAP HANA systems are successfully deployed, you need to create and mount directories for the NUMA nodes in the tmpfs file system.

Display the NUMA topology of your VM

Before you can map the required tmpfs file system, you need to know how many NUMA nodes your VM has. To display the available NUMA nodes on a Compute Engine VM, enter the following command:

lscpu | grep NUMA

For example, an m2-ultramem-208 VM type has four NUMA nodes, numbered 0-3, as shown in the following example:

NUMA node(s):        4
NUMA node0 CPU(s):   0-25,104-129
NUMA node1 CPU(s):   26-51,130-155
NUMA node2 CPU(s):   52-77,156-181
NUMA node3 CPU(s):   78-103,182-207

Create the NUMA node directories

Create a directory for each NUMA node in your VM and set the permissions.

For example, for four NUMA nodes that are numbered 0-3:

mkdir -pv /hana/tmpfs{0..3}/SID
chown -R SID_LCadm:sapsys /hana/tmpfs*/SID
chmod 777 -R /hana/tmpfs*/SID

Mount the NUMA node directories to tmpfs

Mount the tmpfs file system directories and specify a NUMA node preference for each with mpol=prefer:

SID specify the SID with uppercase letters.

mount tmpfsSID0 -t tmpfs -o mpol=prefer:0 /hana/tmpfs0/SID
mount tmpfsSID1 -t tmpfs -o mpol=prefer:1 /hana/tmpfs1/SID
mount tmpfsSID2 -t tmpfs -o mpol=prefer:2 /hana/tmpfs2/SID
mount tmpfsSID3 -t tmpfs -o mpol=prefer:3 /hana/tmpfs3/SID

Note: if you change machine types and the NUMA nodes increase or decrease, you need to modify the tmpfs file system and the [persistence] section of the SAP HANA INI file, shown in the next section, to match the new number of NUMA nodes.

Update /etc/fstab

To ensure that the mount points are available after an operating system reboot, add entries into the file system table, /etc/fstab:

tmpfsSID0 /hana/tmpfs0/SID tmpfs rw,relatime,mpol=prefer:0
tmpfsSID1 /hana/tmpfs1/SID tmpfs rw,relatime,mpol=prefer:1
tmpfsSID1 /hana/tmpfs2/SID tmpfs rw,relatime,mpol=prefer:2
tmpfsSID1 /hana/tmpfs3/SID tmpfs rw,relatime,mpol=prefer:3

Optional: set limits on memory usage

The tmpfs file system can grow and shrink dynamically.

To limit the memory used by the tmpfs file system, you can set a size limit for a NUMA node volume with the size option. For example:

mount tmpfsSID0 -t tmpfs -o mpol=prefer:0,size=250G /hana/tmpfs0/SID

You can also limit overall tmpfs memory usage for all NUMA nodes for a given SAP HANA instance and a given server node by setting the persistent_memory_global_allocation_limit parameter in the [memorymanager] section of the global.ini file.

SAP HANA configuration for Fast Restart

To configure SAP HANA for Fast Restart, update the global.ini file and specify the tables to store in persistent memory.

Update the [persistence] section in the global.ini file

Configure the [persistence] section in the SAP HANA global.ini file to reference the tmpfs locations. Separate each tmpfs location with a semicolon:

[persistence]
basepath_datavolumes = /hana/data
basepath_logvolumes = /hana/log
basepath_persistent_memory_volumes = /hana/tmpfs0/SID;/hana/tmpfs1/SID;/hana/tmpfs2/SID;/hana/tmpfs3/SID

The preceding example specifies four memory volumes for four NUMA nodes, which corresponds to the m2-ultramem-208. If you were running on the m2-ultramem-416, you would need to configure eight memory volumes (0..7).

Restart SAP HANA after modifying the global.ini file.

SAP HANA can now use the tmpfs location as persistent memory space.

Specify the tables to store in persistent memory

Specify specific column tables or partitions to store in persistent memory.

For example, to turn on persistent memory for an existing table, execute the SQL query:

ALTER TABLE exampletable persistent memory ON immediate CASCADE

To change the default for new tables add the parameter table_default in the indexserver.ini file. For example:

[persistent_memory]
table_default = ON

For more information on how to control columns, tables and which monitoring views provide detailed information, see SAP HANA Persistent Memory.

Automated steps

The automation script that Google Cloud provides to enable SAP HANA Fast Restart makes changes to directories /hana/tmpfs*, file /etc/fstab, and SAP HANA configuration. When you run the script, you might need to perform additional steps depending on whether this is the initial deployment of your SAP HANA system or you are resizing your machine to a different NUMA size.

For the initial deployment of your SAP HANA system or resizing the machine to increase the number of NUMA nodes, make sure that SAP HANA is running during the execution of automation script that Google Cloud provides to enable SAP HANA Fast Restart.

When you resize your machine to decrease the number of NUMA nodes, make sure that SAP HANA is stopped during the execution of the automation script that Google Cloud provides to enable SAP HANA Fast Restart. After the script is executed, you need to manually update the SAP HANA configuration to complete the SAP HANA Fast Restart setup. For more information, see SAP HANA configuration for Fast Restart.

Note: We strongly recommend that you run the script that Google Cloud provides to enable SAP HANA Fast Restart in a non-production environment and verify the results thoroughly before running the script in production environments. You assume the responsibility for correctly enabling SAP HANA Fast Restart.

To enable SAP HANA Fast Restart, follow these steps:

1. Establish an SSH connection with your host VM.

2. Switch to root:

   sudo su -

3. Download the sap_lib_hdbfr.sh script:

   wget https://storage.googleapis.com/cloudsapdeploy/terraform/latest/terraform/lib/sap_lib_hdbfr.sh

4. Make the file executable:

   chmod +x sap_lib_hdbfr.sh

5. Verify that the script has no errors:

   vi sap_lib_hdbfr.sh
   ./sap_lib_hdbfr.sh -help

   If the command returns an error, contact Cloud Customer Care. For more information about contacting Customer Care, see Getting support for SAP on Google Cloud.

6. Run the script after replacing SAP HANA system ID (SID) and password for the SYSTEM user of the SAP HANA database. To securely provide the password, we recommend that you use a secret in Secret Manager.

   Run the script by using the name of a secret in Secret Manager. This secret must exist in the Google Cloud project that contains your host VM instance.

   sudo ./sap_lib_hdbfr.sh -h 'SID' -s SECRET_NAME 

   Replace the following:

   • SID: specify the SID with uppercase letters. For example, AHA.
   • SECRET_NAME: specify the name of the secret that corresponds to the password for the SYSTEM user of the SAP HANA database. This secret must exist in the Google Cloud project that contains your host VM instance.

   Alternatively, you can run the script using a plain text password. After SAP HANA Fast Restart is enabled, make sure to change your password. Using plain text password is not recommended as your password would be recorded in the command-line history of your VM.

   sudo ./sap_lib_hdbfr.sh -h 'SID' -p 'PASSWORD'

   Replace the following:

   • SID: specify the SID with uppercase letters. For example, AHA.
   • PASSWORD: specify the password for the SYSTEM user of the SAP HANA database.

For a successful initial run, you should see an output similar to the following:

INFO - Script is running in standalone mode
ls: cannot access '/hana/tmpfs*': No such file or directory
INFO - Setting up HANA Fast Restart for system 'TST/00'.
INFO - Number of NUMA nodes is 2
INFO - Number of directories /hana/tmpfs* is 0
INFO - HANA version 2.57
INFO - No directories /hana/tmpfs* exist. Assuming initial setup.
INFO - Creating 2 directories /hana/tmpfs* and mounting them
INFO - Adding /hana/tmpfs* entries to /etc/fstab. Copy is in /etc/fstab.20220625_030839
INFO - Updating the HANA configuration.
INFO - Running command: select * from dummy
DUMMY
"X"
1 row selected (overall time 4124 usec; server time 130 usec)

INFO - Running command: ALTER SYSTEM ALTER CONFIGURATION ('global.ini', 'SYSTEM') SET ('persistence', 'basepath_persistent_memory_volumes') = '/hana/tmpfs0/TST;/hana/tmpfs1/TST;'
0 rows affected (overall time 3570 usec; server time 2239 usec)

INFO - Running command: ALTER SYSTEM ALTER CONFIGURATION ('global.ini', 'SYSTEM') SET ('persistent_memory', 'table_unload_action') = 'retain';
0 rows affected (overall time 4308 usec; server time 2441 usec)

INFO - Running command: ALTER SYSTEM ALTER CONFIGURATION ('indexserver.ini', 'SYSTEM') SET ('persistent_memory', 'table_default') = 'ON';
0 rows affected (overall time 3422 usec; server time 2152 usec)

Configure SSH keys on the primary and secondary VMs

The SAP HANA secure store (SSFS) keys need to be synchronized between the hosts in the HA cluster. To simplify the synchronization, and to allow files like backups to be copied between the hosts in the HA cluster, these instructions have you create root SSH connections between the two hosts.

Your organization is likely to have guidelines that govern internal network communications. If necessary, after deployment is complete you can remove the metadata from the VMs and the keys from the authorized_keys directory.

If setting up direct SSH connections does not comply with your organization's guidelines, you can synchronize the SSFS keys and transfer files by using other methods, such as:

• Transfer smaller files through your local workstation by using the Cloud Shell Upload file and Download file menu options. See Managing files with Cloud Shell.
• Exchange files using a Google Cloud Storage bucket. See Working with objects in the Cloud Storage documentation.
• Use the Cloud Storage Backint agent for SAP HANA to backup and restore HANA databases. See Cloud Storage Backint agent for SAP HANA.
• Use a file storage solution like Filestore or NetApp Cloud Volumes Service to create a shared folder. See File server options.

To enable SSH connections between the primary and secondary instances, follow these steps.

1. On the primary host VM:

   1. SSH into the VM.

   2. Switch to root:

   $ sudo su -

   1. As root, generate an SSH key.

      # ssh-keygen

   2. Update the primary VM's metadata with information about the SSH key for the secondary VM.

      # gcloud compute instances add-metadata secondary-host-name \
      --metadata "ssh-keys=$(whoami):$(cat ~/.ssh/id_rsa.pub)" --zone secondary-zone

   3. Authorize the primary VM to itself

      # cat ~/.ssh/id_rsa.pub >> ~/.ssh/authorized_keys

2. On the secondary host VM:

   1. SSH into the VM.

   2. Switch to root:

   $ sudo su -

   1. As root, generate an SSH key.

      # ssh-keygen

   2. Update the secondary VM's metadata with information about the SSH key for the primary VM.

      # gcloud compute instances add-metadata primary-host-name \
      --metadata "ssh-keys=$(whoami):$(cat ~/.ssh/id_rsa.pub)" --zone primary-zone

   3. Authorize the secondary VM to itself

      # cat ~/.ssh/id_rsa.pub >> ~/.ssh/authorized_keys

   4. Confirm that the SSH keys are set up properly by opening an SSH connection from the secondary system to the primary system.

      # ssh primary-host-name

3. On the primary host VM as root, confirm the connection by opening an SSH connection to the secondary host VM:

   # ssh secondary-host-name

Create an SAP HANA database user for monitoring the cluster state

1. On the primary host, as SID_LCadm, sign into the SAP HANA database interactive terminal:

   > hdbsql -u system -p "system-password" -i inst_num

2. In the interactive terminal, create the slehasync database user:

   => CREATE USER slehasync PASSWORD "hdb-user-password";
   => GRANT CATALOG READ TO slehasync;
   => GRANT MONITOR ADMIN TO slehasync;
   => ALTER USER slehasync DISABLE PASSWORD LIFETIME;

3. As SID_LCadm, define the SLEHALOC user key in the SAP HANA secure user store (hdbuserstore):

   > PATH="$PATH:/usr/sap/SID/HDBinst_num/exe"
   > hdbuserstore SET SLEHALOC localhost:3inst_num15 slehasync hdb-user-password

Back up the databases

Create backups of your databases to initiate database logging for SAP HANA system replication and create a recovery point.

If you have multiple tenant databases in an MDC configuration, back up each tenant database.

The Deployment Manager template uses /hanabackup/data/SID as the default backup directory.

To create backups of new SAP HANA databases:

1. On the primary host, switch to SID_LCadm. Depending on your OS image, the command might be different.

   sudo -i -u SID_LCadm

2. Create database backups:

   • For a SAP HANA single-database-container system:

     > hdbsql -t -u system -p SYSTEM_PASSWORD -i INST_NUM \
       "backup data using file ('full')"

     The following example shows a successful response from a new SAP HANA system:

     0 rows affected (overall time 18.416058 sec; server time 18.414209 sec)

   • For a SAP HANA multi-database-container system (MDC), create a backup of the system database as well as any tenant databases:

     > hdbsql -t -d SYSTEMDB -u system -p SYSTEM_PASSWORD -i INST_NUM \
       "backup data using file ('full')"

     > hdbsql -t -d SID -u system -p SYSTEM_PASSWORD -i INST_NUM \
       "backup data using file ('full')"

   The following example shows a successful response from a new SAP HANA system:

   0 rows affected (overall time 16.590498 sec; server time 16.588806 sec)

3. Confirm that the logging mode is set to normal:

   > hdbsql -u system -p SYSTEM_PASSWORD -i INST_NUM \
     "select value from "SYS"."M_INIFILE_CONTENTS" where key='log_mode'"

   You should see:

   VALUE
   "normal"

Enable SAP HANA system replication

As a part of enabling SAP HANA system replication, you need to copy the data and key files for the SAP HANA secure stores on the file system (SSFS) from the primary host to the secondary host. The method that this procedure uses to copy the files is just one possible method that you can use.

1. On the primary host as SID_LCadm, enable system replication:

   > hdbnsutil -sr_enable --name=PRIMARY_HOST_NAME

2. On the secondary host:

   1. As SID_LCadm, stop SAP HANA:

      > HDB stop

   2. As root, archive the existing SSFS data and key files:

      # cd /usr/sap/SID/SYS/global/security/rsecssfs/
      # mv data/SSFS_SID.DAT data/SSFS_SID.DAT-ARC
      # mv key/SSFS_SID.KEY key/SSFS_SID.KEY-ARC

   3. Copy the data file from the primary host:

      # scp -o StrictHostKeyChecking=no \
      PRIMARY_HOST_NAME:/usr/sap/SID/SYS/global/security/rsecssfs/data/SSFS_SID.DAT \
      /usr/sap/SID/SYS/global/security/rsecssfs/data/SSFS_SID.DAT

   4. Copy the key file from the primary host:

      # scp -o StrictHostKeyChecking=no \
      PRIMARY_HOST_NAME:/usr/sap/SID/SYS/global/security/rsecssfs/key/SSFS_SID.KEY \
      /usr/sap/SID/SYS/global/security/rsecssfs/key/SSFS_SID.KEY

   5. Update ownership of the files:

      # chown SID_LCadm:sapsys /usr/sap/SID/SYS/global/security/rsecssfs/data/SSFS_SID.DAT
      # chown SID_LCadm:sapsys /usr/sap/SID/SYS/global/security/rsecssfs/key/SSFS_SID.KEY

   6. Update permissions for the files:

      # chmod 644 /usr/sap/SID/SYS/global/security/rsecssfs/data/SSFS_SID.DAT
      # chmod 640 /usr/sap/SID/SYS/global/security/rsecssfs/key/SSFS_SID.KEY

   7. As SID_LCadm, register the secondary SAP HANA system with SAP HANA system replication:

      > hdbnsutil -sr_register --remoteHost=PRIMARY_HOST_NAME --remoteInstance=INST_NUM \
      --replicationMode=syncmem --operationMode=logreplay --name=SECONDARY_HOST_NAME

   8. As SID_LCadm, start SAP HANA:

      > HDB start

Validating system replication

On the primary host as SID_LCadm, confirm that SAP HANA system replication is active by running the following python script:

$ python $DIR_INSTANCE/exe/python_support/systemReplicationStatus.py

If replication is set up properly, among other indicators, the following values are displayed for the xsengine, nameserver, and indexserver services:

• The Secondary Active Status is YES
• The Replication Status is ACTIVE

Also, the overall system replication status shows ACTIVE.

Enable the SAP HANA HA/DR provider hooks

SUSE recommends that you enable the SAP HANA HA/DR provider hooks, which allows SAP HANA to send out notifications for certain events and improves failure detection. The SAP HANA HA/DR provider hooks require SAP HANA 2.0 SPS 03 or a later version.

Note: If you want to implement the HA/DR provider hooks on a pre-existing SAP HANA system with near-zero downtime, then instead refer to the SAP HANA operations guide.

On both the primary and secondary site, complete the following steps:

1. As SID_LCadm, stop SAP HANA:

   > HDB stop

1. As root or SID_LCadm, open the global.ini file for editing:

   > vi /hana/shared/SID/global/hdb/custom/config/global.ini

2. Add the following definitions to the global.ini file:

   [ha_dr_provider_SAPHanaSR]
   provider = SAPHanaSR
   path = /usr/share/SAPHanaSR/
   execution_order = 1
   
   [ha_dr_provider_suschksrv]
   provider = susChkSrv
   path = /usr/share/SAPHanaSR/
   execution_order = 3
   action_on_lost = stop
   
   [trace]
   ha_dr_saphanasr = info

3. As root, create a custom configuration file in the /etc/sudoers.d directory by running the following command. This new configuration file allows the SID_LCadm user to access the cluster node attributes when the srConnectionChanged() hook method is called.

   > sudo visudo -f /etc/sudoers.d/SAPHanaSR

4. In the /etc/sudoers.d/SAPHanaSR file, add the following text:

   Replace the following:

   • SITE_A: the site name of the primary SAP HANA server
   • SITE_B: the site name of the secondary SAP HANA server
   • SID_LC: the SID, specified using lowercase letters
   To view the site names, you can execute the command crm_mon -A1 | grep site, as the root user, on either the SAP HANA primary server or the secondary server.

   Cmnd_Alias SOK_SITEA = /usr/sbin/crm_attribute -n hana_SID_LC_site_srHook_SITE_A -v SOK -t crm_config -s SAPHanaSR
   Cmnd_Alias SFAIL_SITEA = /usr/sbin/crm_attribute -n hana_SID_LC_site_srHook_SITE_A -v SFAIL -t crm_config -s SAPHanaSR
   Cmnd_Alias SOK_SITEB = /usr/sbin/crm_attribute -n hana_SID_LC_site_srHook_SITE_B -v SOK -t crm_config -s SAPHanaSR
   Cmnd_Alias SFAIL_SITEB = /usr/sbin/crm_attribute -n hana_SID_LC_site_srHook_SITE_B -v SFAIL -t crm_config -s SAPHanaSR
   SID_LCadm ALL=(ALL) NOPASSWD: SOK_SITEA, SFAIL_SITEA, SOK_SITEB, SFAIL_SITEB

5. In your /etc/sudoers file, make sure that the following text is included:

   • For SLES for SAP 15 SP3 and higher:

     @includedir /etc/sudoers.d

   • For versions up to SLES for SAP 15 SP2:

     #includedir /etc/sudoers.d

     Note that the # in this text is part of the syntax and does not mean that the line is a comment.

   Note: While the procedure in this section is recommended by SUSE, you can use an alternative approach. Instead of creating a drop-in configuration file, you can add the required access directly to your /etc/sudoers file.

6. As SID_LCadm, start SAP HANA:

   > HDB start

7. After you complete the cluster configuration for SAP HANA, you can verify that the hook functions correctly during a failover test as described in Troubleshooting the SAPHanaSR python hook and HA cluster takeover takes too long on HANA indexserver failure.

Configure the Cloud Load Balancing failover support

The internal passthrough Network Load Balancer service with failover support routes traffic to the active host in an SAP HANA cluster based on a health check service.

Reserve an IP address for the virtual IP

The virtual IP (VIP) address , which is sometimes referred to as a floating IP address, follows the active SAP HANA system. The load balancer routes traffic that is sent to the VIP to the VM that is currently hosting the active SAP HANA system.

1. Open Cloud Shell:

   Go to Cloud Shell

2. Reserve an IP address for the virtual IP. This is the IP address that applications use to access SAP HANA. If you omit the --addresses flag, an IP address in the specified subnet is chosen for you:

   $ gcloud compute addresses create VIP_NAME \
     --region CLUSTER_REGION --subnet CLUSTER_SUBNET \
     --addresses VIP_ADDRESS

   For more information about reserving a static IP, see Reserving a static internal IP address.

3. Confirm IP address reservation:

   $ gcloud compute addresses describe VIP_NAME \
     --region CLUSTER_REGION

   You should see output similar to the following example:

   address: 10.0.0.19
   addressType: INTERNAL
   creationTimestamp: '2020-05-20T14:19:03.109-07:00'
   description: ''
   id: '8961491304398200872'
   kind: compute#address
   name: vip-for-hana-ha
   networkTier: PREMIUM
   purpose: GCE_ENDPOINT
   region: https://www.googleapis.com/compute/v1/projects/example-project-123456/regions/us-central1
   selfLink: https://www.googleapis.com/compute/v1/projects/example-project-123456/regions/us-central1/addresses/vip-for-hana-ha
   status: RESERVED
   subnetwork: https://www.googleapis.com/compute/v1/projects/example-project-123456/regions/us-central1/subnetworks/example-subnet-us-central1

Create instance groups for your host VMs

1. In Cloud Shell, create two unmanaged instance groups and assign the primary master host VM to one and the secondary master host VM to the other:

   $ gcloud compute instance-groups unmanaged create PRIMARY_IG_NAME \
     --zone=PRIMARY_ZONE
   $ gcloud compute instance-groups unmanaged add-instances PRIMARY_IG_NAME \
     --zone=PRIMARY_ZONE \
     --instances=PRIMARY_HOST_NAME
   $ gcloud compute instance-groups unmanaged create SECONDARY_IG_NAME \
     --zone=SECONDARY_ZONE
   $ gcloud compute instance-groups unmanaged add-instances SECONDARY_IG_NAME \
     --zone=SECONDARY_ZONE \
     --instances=SECONDARY_HOST_NAME
   

2. Confirm the creation of the instance groups:

   $ gcloud compute instance-groups unmanaged list

   You should see output similar to the following example:

   NAME          ZONE           NETWORK          NETWORK_PROJECT        MANAGED  INSTANCES
   hana-ha-ig-1  us-central1-a  example-network  example-project-123456 No       1
   hana-ha-ig-2  us-central1-c  example-network  example-project-123456 No       1

Create a Compute Engine health check

1. In Cloud Shell, create the health check. For the port used by the health check, choose a port that is in the private range, 49152-65535, to avoid clashing with other services. The check-interval and timeout values are slightly longer than the defaults so as to increase failover tolerance during Compute Engine live migration events. You can adjust the values, if necessary:

   $ gcloud compute health-checks create tcp HEALTH_CHECK_NAME --port=HEALTHCHECK_PORT_NUM \
     --proxy-header=NONE --check-interval=10 --timeout=10 --unhealthy-threshold=2 \
     --healthy-threshold=2

2. Confirm the creation of the health check:

   $ gcloud compute health-checks describe HEALTH_CHECK_NAME

   You should see output similar to the following example:

   checkIntervalSec: 10
   creationTimestamp: '2020-05-20T21:03:06.924-07:00'
   healthyThreshold: 2
   id: '4963070308818371477'
   kind: compute#healthCheck
   name: hana-health-check
   selfLink: https://www.googleapis.com/compute/v1/projects/example-project-123456/global/healthChecks/hana-health-check
   tcpHealthCheck:
    port: 60000
    portSpecification: USE_FIXED_PORT
    proxyHeader: NONE
   timeoutSec: 10
   type: TCP
   unhealthyThreshold: 2

Create a firewall rule for the health checks

Define a firewall rule for a port in the private range that allows access to your host VMs from the IP ranges that are used by Compute Engine health checks, 35.191.0.0/16 and 130.211.0.0/22. For more information, see Creating firewall rules for health checks.

1. If you don't already have one, add a network tag to your host VMs. This network tag is used by the firewall rule for health checks.

   $ gcloud compute instances add-tags PRIMARY_HOST_NAME \
     --tags NETWORK_TAGS \
     --zone PRIMARY_ZONE
   $ gcloud compute instances add-tags SECONDARY_HOST_NAME \
     --tags NETWORK_TAGS \
     --zone SECONDARY_ZONE
   

2. If you don't already have one, create a firewall rule to allow the health checks:

   $ gcloud compute firewall-rules create RULE_NAME \
     --network NETWORK_NAME \
     --action ALLOW \
     --direction INGRESS \
     --source-ranges 35.191.0.0/16,130.211.0.0/22 \
     --target-tags NETWORK_TAGS \
     --rules tcp:HLTH_CHK_PORT_NUM

   For example:

   gcloud compute firewall-rules create  fw-allow-health-checks \
   --network example-network \
   --action ALLOW \
   --direction INGRESS \
   --source-ranges 35.191.0.0/16,130.211.0.0/22 \
   --target-tags cluster-ntwk-tag \
   --rules tcp:60000

Configure the load balancer and failover group

1. Create the load balancer backend service:

   $ gcloud compute backend-services create BACKEND_SERVICE_NAME \
     --load-balancing-scheme internal \
     --health-checks HEALTH_CHECK_NAME \
     --no-connection-drain-on-failover \
     --drop-traffic-if-unhealthy \
     --failover-ratio 1.0 \
     --region CLUSTER_REGION \
     --global-health-checks

2. Add the primary instance group to the backend service:

   $ gcloud compute backend-services add-backend BACKEND_SERVICE_NAME \
     --instance-group PRIMARY_IG_NAME \
     --instance-group-zone PRIMARY_ZONE \
     --region CLUSTER_REGION

3. Add the secondary, failover instance group to the backend service:

   $ gcloud compute backend-services add-backend BACKEND_SERVICE_NAME \
     --instance-group SECONDARY_IG_NAME \
     --instance-group-zone SECONDARY_ZONE \
     --failover \
     --region CLUSTER_REGION

4. Create a forwarding rule. For the IP address, specify the IP address that you reserved for the VIP. If you need to access the SAP HANA system from outside of the region that is specified below, include the flag --allow-global-access in the definition:

   $ gcloud compute forwarding-rules create RULE_NAME \
     --load-balancing-scheme internal \
     --address VIP_ADDRESS \
     --subnet CLUSTER_SUBNET \
     --region CLUSTER_REGION \
     --backend-service BACKEND_SERVICE_NAME \
     --ports ALL

   For more information about cross-region access to your SAP HANA high-availability system, see Internal TCP/UDP Load Balancing.

Note: Your backend instance groups won't register as healthy until you have completed the Pacemaker cluster configuration.

Test the load balancer configuration

Even though your backend instance groups won't register as healthy until later, you can test the load balancer configuration by setting up a listener to respond to the health checks. After setting up a listener, if the load balancer is configured correctly, the status of the backend instance groups changes to healthy.

The following sections present different methods that you can use to test the configuration.

Testing the load balancer with the socat utility

You can use the socat utility to temporarily listen on the health check port. You need to install the socatutility anyway, because you use it later when you configure cluster resources.

1. On both host VMs as root, install the socat utility:

   # zypper install -y socat

2. Start a socat process to listen for 60 seconds on the health check port:

   # timeout 60s socat - TCP-LISTEN:HLTH_CHK_PORT_NUM,fork

3. In Cloud Shell, after waiting a few seconds for the health check to detect the listener, check the health of your backend instance groups:

   $ gcloud compute backend-services get-health BACKEND_SERVICE_NAME \
     --region CLUSTER_REGION

   You should see output similar to the following:

   ---
   backend: https://www.googleapis.com/compute/v1/projects/example-project-123456/zones/us-central1-a/instanceGroups/hana-ha-ig-1
   status:
    healthStatus:
    ‐ healthState: HEALTHY
      instance: https://www.googleapis.com/compute/v1/projects/example-project-123456/zones/us-central1-a/instances/hana-ha-vm-1
      ipAddress: 10.0.0.35
      port: 80
    kind: compute#backendServiceGroupHealth
   ---
   backend: https://www.googleapis.com/compute/v1/projects/example-project-123456/zones/us-central1-c/instanceGroups/hana-ha-ig-2
   status:
    healthStatus:
    ‐ healthState: HEALTHY
      instance: https://www.googleapis.com/compute/v1/projects/example-project-123456/zones/us-central1-c/instances/hana-ha-vm-2
      ipAddress: 10.0.0.34
      port: 80
    kind: compute#backendServiceGroupHealth

Testing the load balancer using port 22

If port 22 is open for SSH connections on your host VMs, you can temporarily edit the health checker to use port 22, which has a listener that can respond to the health checker.

To temporarily use port 22, follow these steps:

1. Click your health check in the console:

   Go to Health checks page

2. Click Edit.

3. In the Port field, change the port number to 22.

4. Click Save and wait a minute or two.

5. In Cloud Shell, check the health of your backend instance groups:

   $ gcloud compute backend-services get-health BACKEND_SERVICE_NAME \
     --region CLUSTER_REGION

   You should see output similar to the following:

   ---
   backend: https://www.googleapis.com/compute/v1/projects/example-project-123456/zones/us-central1-a/instanceGroups/hana-ha-ig-1
   status:
    healthStatus:
    ‐ healthState: HEALTHY
      instance: https://www.googleapis.com/compute/v1/projects/example-project-123456/zones/us-central1-a/instances/hana-ha-vm-1
      ipAddress: 10.0.0.35
      port: 80
    kind: compute#backendServiceGroupHealth
   ---
   backend: https://www.googleapis.com/compute/v1/projects/example-project-123456/zones/us-central1-c/instanceGroups/hana-ha-ig-2
   status:
    healthStatus:
    ‐ healthState: HEALTHY
      instance: https://www.googleapis.com/compute/v1/projects/example-project-123456/zones/us-central1-c/instances/hana-ha-vm-2
      ipAddress: 10.0.0.34
      port: 80
    kind: compute#backendServiceGroupHealth

6. When you are done, change the health check port number back to the original port number.

Set up Pacemaker

The following procedure configures the SUSE implementation of a Pacemaker cluster on Compute Engine VMs for SAP HANA.

For more information about the configuring high-availability clusters on SLES, see the SUSE Linux Enterprise High Availability Extension documentation for your version of SLES.

Create the Corosync configuration files

1. Create a Corosync configuration file on the primary host:

   1. Create the following file:

       vi /etc/corosync/corosync.conf

   2. In the corosync.conf file on the primary host, add the following configuration, replacing the italic variable text with your values:

      totem {
       version: 2
       secauth: off
       crypto_hash: sha1
       crypto_cipher: aes256
       cluster_name: hacluster
       clear_node_high_bit: yes
       token: 20000
       token_retransmits_before_loss_const: 10
       join: 60
       max_messages:  20
       transport: udpu
       interface {
         ringnumber: 0
         Bindnetaddr: static-ip-of-hdb-on-this-host
         mcastport: 5405
         ttl: 1
       }
      }
      logging {
       fileline:  off
       to_stderr: no
       to_logfile: no
       logfile: /var/log/cluster/corosync.log
       to_syslog: yes
       debug: off
       timestamp: on
       logger_subsys {
         subsys: QUORUM
         debug: off
       }
      }
      nodelist {
       node {
         ring0_addr: this-host-name
         nodeid: 1
       }
       node {
         ring0_addr: other-host-name
         nodeid: 2
       }
      }
      quorum {
       provider: corosync_votequorum
       expected_votes: 2
       two_node: 1
      }

2. Create a Corosync configuration file on the secondary host by repeating the same steps you used for the primary host. Except for the static IP of the HDB on the Bindnetaddr property and the order of the host names in the nodelist, the configuration file property values are the same for each host.

Initialize the cluster

1. On the primary host as root:

   1. Change the password for the hacluster user:

      # passwd hacluster

   2. Initialize the cluster:

      # corosync-keygen
      # crm cluster init --yes ssh
      # crm cluster init -y csync2

   3. Start Pacemaker on the primary host:

      # systemctl enable pacemaker
      # systemctl start pacemaker

2. On the secondary host as root:

   1. Change the password for the hacluster user:

      # passwd hacluster

   2. Join the secondary host to the cluster that is initialized on the primary host:

      # crm cluster join --yes ssh
      # crm cluster join -y -c primary-host-name csync2

   3. Start Pacemaker on the secondary host:

      # systemctl enable pacemaker
      # systemctl start pacemaker

3. On either host as root, confirm that the cluster shows both nodes:

   # crm_mon -s

   You should see output similar to the following:

   CLUSTER OK: 2 nodes online, 0 resources configured

Configure the cluster

To configure the cluster, you define general cluster properties and the cluster primitive resources.

Enable maintenance mode

1. On either host as root, put the cluster in maintenance mode:

   # crm configure property maintenance-mode="true"

Configure the general cluster properties

1. On the primary host:

   1. Set the general cluster properties:

      # crm configure property stonith-timeout="300s"
      # crm configure property stonith-enabled="true"
      # crm configure rsc_defaults resource-stickiness="1000"
      # crm configure rsc_defaults migration-threshold="5000"
      # crm configure op_defaults timeout="600"

Set up fencing

You set up fencing by defining a cluster resource with a fence agent for each host VM.

To ensure the correct sequence of events after a fencing action, you also configure the operating system to delay the restart of Corosync after a VM is fenced. You also adjust the Pacemaker timeout for reboots to account for the delay.

Create the fencing device resources

1. On the primary host as root, create the fencing resources:

   # crm configure primitive STONITH-"primary-host-name" stonith:fence_gce \
       op monitor interval="300s" timeout="120s" \
       op start interval="0" timeout="60s" \
       params port="primary-host-name" zone="primary-zone" project="project_id" \
       pcmk_reboot_timeout=300 pcmk_monitor_retries=4 pcmk_delay_max=30

   # crm configure primitive STONITH-"secondary-host-name" stonith:fence_gce \
       op monitor interval="300s" timeout="120s" \
       op start interval="0" timeout="60s" \
       params port="secondary-host-name" zone="secondary-zone" project="project_id" \
       pcmk_reboot_timeout=300 pcmk_monitor_retries=4

2. Set the location of each fencing device:

   # crm configure location LOC_STONITH_"primary-host-name" \
       STONITH-"primary-host-name" -inf: "primary-host-name"

   # crm configure location LOC_STONITH_"secondary-host-name" \
       STONITH-"secondary-host-name" -inf: "secondary-host-name"

Set a delay for the restart of Corosync

1. On both hosts as root, create a systemd drop-in file that delays the startup of Corosync to ensure the proper sequence of events after a fenced VM is rebooted:

   systemctl edit corosync.service

2. Add the following lines to the file:

   [Service]
   ExecStartPre=/bin/sleep 60

3. Save the file and exit the editor.

4. Reload the systemd manager configuration.

   systemctl daemon-reload

5. Confirm the drop-in file was created:

   service corosync status

   You should see a line for the drop-in file, as shown in the following example:

   ● corosync.service - Corosync Cluster Engine
      Loaded: loaded (/usr/lib/systemd/system/corosync.service; disabled; vendor preset: disabled)
     Drop-In: /etc/systemd/system/corosync.service.d
              └─override.conf
      Active: active (running) since Tue 2021-07-20 23:45:52 UTC; 2 days ago

Create a local cluster IP resource for the VIP address

To configure the VIP address in the operating system, create a local cluster IP resource for the VIP address that you reserved earlier:

# crm configure primitive rsc_vip_int-primary IPaddr2 \
     params ip=vip-address cidr_netmask=32 nic="eth0" op monitor interval=3600s timeout=60s

Set up the helper health-check service

The load balancer uses a listener on the health-check port of each host to determine where the primary instance of the SAP HANA cluster is running.

To manage the listeners in the cluster, you create a resource for the listener.

These instructions use the socat utility as the listener.

1. On both hosts as root, install the socat utility:

   # zypper in -y socat

2. On the primary host:

   1. Create a resource for the helper health-check service:

      # crm configure primitive rsc_healthcheck-primary anything \
          params binfile="/usr/bin/socat" \
          cmdline_options="-U TCP-LISTEN:healthcheck-port-num,backlog=10,fork,reuseaddr /dev/null" \
          op monitor timeout=20s interval=10s \
          op_params depth=0

Group the VIP and the helper health-check service resources

Group the VIP and helper health-check service resources:

# crm configure group g-primary rsc_vip_int-primary rsc_healthcheck-primary

Create the SAPHanaTopology primitive resource

You define the SAPHanaTopology primitive resource in a temporary configuration file, which you then upload to Corosync.

On the primary host as root:

1. Create a temporary configuration file for the SAPHanaTopology configuration parameters:

   # vi /tmp/cluster.tmp

2. Copy and paste the SAPHanaTopology resource definitions into the /tmp/cluster.tmp file:

   primitive rsc_SAPHanaTopology_SID_HDBinst_num ocf:suse:SAPHanaTopology \
    operations \$id="rsc_sap2_SID_HDBinst_num-operations" \
    op monitor interval="10" timeout="600" \
    op start interval="0" timeout="600" \
    op stop interval="0" timeout="300" \
    params SID="SID" InstanceNumber="inst_num"
   
   clone cln_SAPHanaTopology_SID_HDBinst_num rsc_SAPHanaTopology_SID_HDBinst_num \
    meta clone-node-max="1" target-role="Started" interleave="true"

3. Edit the /tmp/cluster.tmp file to replace the variable text with the SID and instance number for your SAP HANA system.

4. On the primary as root, load the contents of the /tmp/cluster.tmp file into Corosync:

   crm configure load update /tmp/cluster.tmp

Create the SAPHana primitive resource

You define the SAPHana primitive resource by using the same method that you used for the SAPHanaTopology resource: in a temporary configuration file, which you then upload to Corosync.

1. Replace the temporary configuration file:

   # rm /tmp/cluster.tmp
   # vi /tmp/cluster.tmp

2. Copy and paste the SAPHana resource definitions into the /tmp/cluster.tmp file:

   primitive rsc_SAPHana_SID_HDBinst_num ocf:suse:SAPHana \
    operations \$id="rsc_sap_SID_HDBinst_num-operations" \
    op start interval="0" timeout="3600" \
    op stop interval="0" timeout="3600" \
    op promote interval="0" timeout="3600" \
    op demote interval="0" timeout="3600" \
    op monitor interval="60" role="Master" timeout="700" \
    op monitor interval="61" role="Slave" timeout="700" \
    params SID="SID" InstanceNumber="inst_num" PREFER_SITE_TAKEOVER="true" \
    DUPLICATE_PRIMARY_TIMEOUT="7200" AUTOMATED_REGISTER="true"
   
   ms msl_SAPHana_SID_HDBinst_num rsc_SAPHana_SID_HDBinst_num \
    meta notify="true" clone-max="2" clone-node-max="1" \
    target-role="Started" interleave="true"
   
   colocation col_saphana_ip_SID_HDBinst_num 4000: g-primary:Started \
    msl_SAPHana_SID_HDBinst_num:Master
   order ord_SAPHana_SID_HDBinst_num Optional: cln_SAPHanaTopology_SID_HDBinst_num \
    msl_SAPHana_SID_HDBinst_num

   For a multi-tier SAP HANA HA cluster, if you are using a version earlier than SAP HANA 2.0 SP03, set AUTOMATED_REGISTER to false. This prevents a recovered instance from attempting to self-register for replication to a HANA system that already has a replication target configured. For SAP HANA 2.0 SP03 or later, you can set AUTOMATED_REGISTER to true for SAP HANA configurations that use multitier system replication. For additional information, see:

   • SAP HANA System Replication Scale-Up
   • HANA Scale-Up HA with System Replication & Automated Failover

3. On the primary as root, load the contents of the /tmp/cluster.tmp file into Corosync:

   crm configure load update /tmp/cluster.tmp

Confirm SAP HANA system replication is active

1. On the primary host, as SID_LCadm, sign into the SAP HANA database interactive terminal:

   > hdbsql -u system -p "system-password" -i inst_num

2. In the interactive terminal, check replication status:

   => select distinct REPLICATION_STATUS from SYS.M_SERVICE_REPLICATION

   The REPLICATION_STATUS should be "ACTIVE".

Alternatively, you can check the replication status by running the following python script as SID_LCadm:

# python $DIR_INSTANCE/exe/python_support/systemReplicationStatus.py

Activate the cluster

1. On the primary host as root, take the cluster out of maintenance mode:

   # crm configure property maintenance-mode="false"

   If you receive a prompt that asks you to remove "maintenance", enter y.

2. Wait 15 seconds and then on the primary host as root, check the status of the cluster:

   # crm status

   The following examples shows the status of an active, properly configured cluster:

   Stack: corosync
   Current DC: hana-ha-vm-1 (version 2.0.1+20190417.13d370ca9-3.9.1-2.0.1+20190417.13d370ca9) - partition with quorum
   Last updated: Sun Jun  7 00:36:56 2020
   Last change: Sun Jun  7 00:36:53 2020 by root via crm_attribute on hana-ha-vm-1
   
   2 nodes configured
   8 resources configured
   
   Online: [ hana-ha-vm-1 hana-ha-vm-2 ]
   
   Full list of resources:
   
   STONITH-hana-ha-vm-1   (stonith:fence_gce):  Started hana-ha-vm-2
   STONITH-hana-ha-vm-2   (stonith:fence_gce):  Started hana-ha-vm-1
   Clone Set: cln_SAPHanaTopology_HA1_HDB22 [rsc_SAPHanaTopology_HA1_HDB22]
       Started: [ hana-ha-vm-1 hana-ha-vm-2 ]
   Resource Group: g-primary
       rsc_vip_int-primary        (ocf::heartbeat:IPaddr2):       Started hana-ha-vm-1
       rsc_healthcheck-primary        (ocf::heartbeat:anything):      Started hana-ha-vm-1
   Clone Set: msl_SAPHana_HA1_HDB22 [rsc_SAPHana_HA1_HDB22] (promotable)
       Masters: [ hana-ha-vm-1 ]
       Slaves: [ hana-ha-vm-2 ]

Test failover

Test your cluster by simulating a failure on the primary host. Use a test system or run the test on your production system before you release the system for use.

Backup the system before the test.

You can simulate a failure in a variety of ways, including:

• HDB stop
• HDB kill
• reboot (on the active node)
• ip link set eth0 down for instances with a single network interface
• iptables ... DROP for instances with multiple network interfaces
• echo c > /proc/sysrq-trigger

These instructions use ip link set eth0 down or iptables to simulate a network disruption between your two hosts in the cluster. Use the ip link command on an instance with a single network interface and use the iptables command on instances with one or more network interfaces. The test validates both failover as well as fencing. In the case where your instances have multiple network interfaces defined, you use the iptables command on the secondary host to drop incoming and outgoing traffic based on the IP used by the primary host for cluster communication, thereby simulating a network connection loss to the primary.

1. On the active host, as root, take the network interface offline:

   # ip link set eth0 down

   Or, if multiple network interfaces are active, using the iptables on the secondary host:

   # iptables -A INPUT -s PRIMARY_CLUSTER_IP -j DROP; iptables -A OUTPUT -d PRIMARY_CLUSTER_IP -j DROP

2. Reconnect to either host using SSH and change to the root user.

3. Enter crm status to confirm that the primary host is now active on the VM that used to contain the secondary host. Automatic restart is enabled in the cluster, so the stopped host will restart and assume the role of secondary host, as shown in the following example.

   Stack: corosync
   Current DC: hana-ha-vm-2 (version 2.0.1+20190417.13d370ca9-3.9.1-2.0.1+20190417.13d370ca9) - partition with quorum
   Last updated: Fri Jun 12 16:46:07 2020
   Last change: Fri Jun 12 16:46:07 2020 by root via crm_attribute on hana-ha-vm-2
   
   2 nodes configured
   8 resources configured
   
   Online: [ hana-ha-vm-1 hana-ha-vm-2 ]
   
   Full list of resources:
   
   STONITH-hana-ha-vm-1   (stonith:fence_gce):  Started hana-ha-vm-2
   STONITH-hana-ha-vm-2   (stonith:fence_gce):  Started hana-ha-vm-1
   
   Clone Set: cln_SAPHanaTopology_HA1_HDB22 [rsc_SAPHanaTopology_HA1_HDB22]
       Started: [ hana-ha-vm-1 hana-ha-vm-2 ]
   Resource Group: g-primary
       rsc_vip_int-primary        (ocf::heartbeat:IPaddr2):       Started hana-ha-vm-2
       rsc_healthcheck-primary        (ocf::heartbeat:anything):      Started hana-ha-vm-2
   Clone Set: msl_SAPHana_HA1_HDB22 [rsc_SAPHana_HA1_HDB22] (promotable)
       Masters: [ hana-ha-vm-2 ]
       Slaves: [ hana-ha-vm-1 ]

Configure HANA Active/Active (Read Enabled)

Starting with SAP HANA 2.0 SPS1, you can configure HANA Active/Active (Read Enabled) in a Pacemaker cluster. This is optional.

To configure HANA Active/Active (Read Enabled) in a Pacemaker cluster, complete the following steps.

Configure the Cloud Load Balancing failover support for the secondary host

The internal passthrough Network Load Balancer service with failover support routes traffic to the secondary host in an SAP HANA cluster based on a health check service.

To configure failover support for the secondary host, follow these steps:

1. Open Cloud Shell:

   Go to Cloud Shell

2. Reserve an IP address for the virtual IP by running the following command.

   The virtual IP (VIP) address follows the secondary SAP HANA system. This is the IP address that applications use to access your secondary SAP HANA system. The load balancer routes traffic that is sent to the VIP to the VM instance that currently hosts the secondary system.

   If you omit the --addresses flag in the following command, then an IP address in the specified subnet is chosen for you. For more information about reserving a static IP, see Reserving a static internal IP address.

   $ gcloud compute addresses create secondary-vip-name \
     --region cluster-region --subnet cluster-subnet \
     --addresses secondary-vip-address

3. Create a Compute Engine health check by running the following command.

   For the port used by the health check, choose a port that is in the private range, 49152-65535, to avoid clashing with other services. The port should be different from the one configured for the health check used for the HANA primary system access. The check-interval and timeout values are slightly longer than the defaults so as to increase failover tolerance during Compute Engine live migration events. You can adjust the values if necessary.

   $ gcloud compute health-checks create tcp secondary-health-check-name \
     --port=secondary-healthcheck-port-num \
     --proxy-header=NONE --check-interval=10 --timeout=10 --unhealthy-threshold=2 \
     --healthy-threshold=2

4. Configure the load balancer and failover group by running the following commands.

   Here you create an additional backend service and use the same instance groups that you created earlier for the backend service behind the Internal TCP/UDP Load Balancer for your SAP HANA primary system.

   1. Create the load balancer backend service:

      $ gcloud compute backend-services create secondary-backend-service-name \
        --load-balancing-scheme internal \
        --health-checks secondary-health-check-name \
        --no-connection-drain-on-failover \
        --drop-traffic-if-unhealthy \
        --failover-ratio 1.0 \
        --region cluster-region \
        --global-health-checks

   2. Add the primary instance group to the backend service:

      $ gcloud compute backend-services add-backend secondary-backend-service-name \
        --instance-group primary-ig-name \
        --instance-group-zone primary-zone \
        --region cluster-region

   3. Add the secondary, failover instance group to the backend service:

      $ gcloud compute backend-services add-backend secondary-backend-service-name \
        --instance-group secondary-ig-name \
        --instance-group-zone secondary-zone \
        --failover \
        --region cluster-region

   4. Create a forwarding rule.

      For the IP address flag, specify the IP address that you reserved for the VIP. If you need to access the HANA secondary system from outside of the region that you specify in the following command, then include the flag --allow-global-access in the forwarding rule's definition.

      $ gcloud compute forwarding-rules create secondary-rule-name \
        --load-balancing-scheme internal \
        --address secondary-vip-name \
        --subnet cluster-subnet \
        --region cluster-region \
        --backend-service secondary-backend-service-name \
        --ports ALL

      For more information about cross-region access to your SAP HANA high-availability system, see Internal TCP/UDP Load Balancing.

Enable HANA Active/Active (Read Enabled)

On your secondary host, enable Active/Active (read enabled) for SAP HANA system replication by following these steps:

1. As root, place the cluster in maintenance mode:

   # crm configure property maintenance-mode="true"

2. As SID_LCadm, stop SAP HANA:

   > HDB stop

3. As SID_LCadm, re-register the HANA secondary system with SAP HANA system replication using the operation mode logreplay_readaccess:

   > hdbnsutil -sr_register --remoteHost=primary-host-name --remoteInstance=inst_num \
    --replicationMode=syncmem --operationMode=logreplay_readaccess --name=secondary-host-name

4. As SID_LCadm, start SAP HANA:

   > HDB start

5. As SID_LCadm, confirm that HANA synchronization status is ACTIVE:

   > cdpy; python systemReplicationStatus.py --sapcontrol=1 | grep overall_replication_status

   You should see an output similar to the following example:

   overall_replication_status=ACTIVE

Configure Pacemaker

Configure your Pacemaker HA cluster for Active/Active (read enabled) by running the following commands as root:

1. Create a local cluster IP resource for the VIP address that you reserver for the secondary system:

   # crm configure primitive rsc_vip_int-secondary IPaddr2 \
     params ip=secondary-vip-address cidr_netmask=32 nic="eth0" \
     op monitor interval=3600s timeout=60s

2. Set up the helper health-check service by running the following commands:

   The load balancer uses a listener on the health-check port of each host to determine where the secondary instance of the SAP HANA cluster is running.

   1. To manage the listeners in the cluster, create a resource for the listener. These instructions use the socat utility as the listener. Create a resource for the helper health-check service:

      # crm configure primitive rsc_healthcheck-secondary anything \
       params binfile="/usr/bin/socat" \
       cmdline_options="-U TCP-LISTEN:secondary-healthcheck-port-num,backlog=10,fork,reuseaddr /dev/null" \
       op monitor timeout=20s interval=10s \
       op_params depth=0

   2. Group the VIP and the helper health-check service resources:

      # crm configure group g-secondary rsc_vip_int-secondary rsc_healthcheck-secondary

3. Create a colocation constraint:

   # crm configure colocation col_saphana_secondary 4000: g-secondary:Started \
     msl_SAPHana_SID_HDBinst_num:Slave

4. Exit cluster maintenance mode:

   # crm configure property maintenance-mode="false"

5. Check the status of the cluster:

   # crm status

   The following examples shows the status of an active, properly configured cluster for SAP HANA system replication with Active/Active (read enabled). You should see an additional resource group for the secondary system's VIP resources. In the following example, the name of that resource group is g-secondary.

   Cluster Summary:
     Stack: corosync
     Current DC: hana-ha-vm-1 (version 2.0.4+20200616.2deceaa3a-3.15.1-2.0.4+20200616.2deceaa3a) - partition with quorum
     Last updated: Fri Oct  7 21:52:46 2022
     Last change:  Fri Oct  7 21:51:42 2022 by root via crm_attribute on hana-ha-vm-1
   
     2 nodes configured
     10 resource instances configured
   
   Node List:
     Online: [ hana-ha-vm-1 hana-ha-vm-2 ]
   
   Active Resources:
     STONITH-hana-ha-vm-1  (stonith:fence_gce):   Started hana-ha-vm-2
     STONITH-hana-ha-vm-2  (stonith:fence_gce):   Started hana-ha-vm-1
     Resource Group: g-primary:
       rsc_vip_int-primary       (ocf::heartbeat:IPaddr2):        Started hana-ha-vm-1
       rsc_vip_hc-primary        (ocf::heartbeat:anything):       Started hana-ha-vm-1
     Clone Set: cln_SAPHanaTopology_HA1_HDB00 [rsc_SAPHanaTopology_HA1_HDB00]:
       Started: [ hana-ha-vm-1 hana-ha-vm-2 ]
     Clone Set: msl_SAPHana_HA1_HDB00 [rsc_SAPHana_HA1_HDB00] (promotable):
       Masters: [ hana-ha-vm-1 ]
       Slaves: [ hana-ha-vm-2 ]
     Resource Group: g-secondary:
       rsc_vip_int-secondary       (ocf::heartbeat:IPaddr2):        Started hana-ha-vm-2
       rsc_healthcheck-secondary   (ocf::heartbeat:anything):       Started hana-ha-vm-2
   

Evaluate your SAP HANA workload

To automate continuous validation checks for your SAP HANA high-availability workloads running on Google Cloud, you can use Workload Manager.

Workload Manager allows you to automatically scan and evaluate your SAP HANA high-availability workloads against best practices from SAP, Google Cloud, and OS vendors. This helps improve the quality, performance, and reliability of your workloads.

For information about the best practices that Workload Manager supports for evaluating SAP HANA high-availability workloads running on Google Cloud, see Workload Manager best practices for SAP. For information about creating and running an evaluation using Workload Manager, see Create and run an evaluation.

Troubleshooting

To troubleshoot problems with high-availability configurations for SAP HANA on SLES, see Troubleshooting high-availability configurations for SAP.

Getting support for SAP HANA on SLES

If you need help resolving a problem with high-availability clusters for SAP HANA on SLES, gather the required diagnostic information and contact Cloud Customer Care. For more information, see High-availability clusters on SLES diagnostic information.

Support

For issues with Google Cloud infrastructure or services, contact Customer Care. You can find the contact information on the Support Overview page in the Google Cloud console. If Customer Care determines that a problem resides in your SAP systems, then you are referred to SAP Support.

For SAP product-related issues, log your support request with SAP support. SAP evaluates the support ticket and, if it appears to be a Google Cloud infrastructure issue, then SAP transfers that ticket to the appropriate Google Cloud component in its system: BC-OP-LNX-GOOGLE or BC-OP-NT-GOOGLE.

Support requirements

Before you can receive support for SAP systems and the Google Cloud infrastructure and services that they use, you must meet the minimum support plan requirements.

For more information about the minimum support requirements for SAP on Google Cloud, see:

• Getting support for SAP on Google Cloud
• SAP Note 2456406 - SAP on Google Cloud Platform: Support Prerequisites (An SAP user account is required)

Connecting to SAP HANA

If the host VMs don't have an external IP address for SAP HANA, you can only connect to the SAP HANA instances through the bastion instance using SSH or through the Windows server through SAP HANA Studio.

• To connect to SAP HANA through the bastion instance, connect to the bastion host, and then to the SAP HANA instance(s) by using an SSH client of your choice.

• To connect to the SAP HANA database through SAP HANA Studio, use a remote desktop client to connect to the Windows Server instance. After connection, manually install SAP HANA Studio and access your SAP HANA database.

Post-deployment tasks

After you complete the deployment, finish with the following steps:

1. Change the temporary passwords for the SAP HANA system administrator and database superuser. For example:

   sudo passwd SID_LCadm

   For information from SAP about changing the password, see Reset the SYSTEM User Password of the System Database.

2. Before using your SAP HANA instance, configure and backup your new SAP HANA database.

3. If your SAP HANA system is deployed on a VirtIO network interface, then we recommend that you ensure the value of the TCP parameter /proc/sys/net/ipv4/tcp_limit_output_bytes is set to 1048576. This modification helps improve the overall network throughput on the VirtIO network interface without affecting the network latency.

For more information, see:

• SAP HANA operations guide.
• SAP HANA Installation and Update Guide.

What's next

See the following resource for more information:

Automated SAP HANA System Replication in Scale-Up in pacemaker cluster

SAP HANA high-availability planning guide

SAP HANA disaster recovery planning guide

For more information about VM administration and monitoring, see the SAP HANA Operations Guide