Terraform: HA cluster configuration guide for SAP NetWeaver on SLES

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This guide shows you how to automate the deployment of a performance-optimized SUSE Linux Enterprise Server (SLES) high-availability (HA) cluster for SAP NetWeaver.

The guide uses Terraform to deploy two Compute Engine virtual machines (VMs), a virtual IP address (VIP) with an internal TCP/UDP load balancer implementation, and an OS-based HA cluster, all according to the best practices from Google Cloud, SAP, and the OS vendor.

For information about deploying Compute Engine VMs for SAP NetWeaver that is not specific to high-availability, see the SAP NetWeaver deployment guide that is specific to your operating system.

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

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

The system that this guide deploys

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

Overview of a high-availability Linux cluster for a single-node SAP NetWeaver system

The deployed cluster includes the following functions and features:

  • Two host VMs, one for the active ASCS instance and one for the active instance of the ENSA2 Enqueue Replicator or the ENSA1 Enqueue Replication Server (ENSA1). Both ENSA2 and ENSA1 instances are referred to as ERS.
  • The Pacemaker high-availability cluster resource manager.
  • A STONITH fencing mechanism.
  • Automatic restart of the failed instance as the new secondary instance.

Prerequisites

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

Except where required for the Google Cloud environment, the information in this guide is consistent with the following related guides from SUSE:

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's monitoring agent. 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 create a VPC network for your project, complete the following steps:

  1. Create a custom mode network. For more information, see Creating a custom mode network.

  2. Create a subnetwork, and specify the region and IP range. For more information, see Adding subnets.

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.

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, incoming connections from outside your Google Cloud network are blocked. To allow incoming connections, set up a firewall rule for your VM. Firewall rules regulate only new incoming connections to a VM. After a connection is established with a VM, traffic is permitted in both directions over that connection.

You can create a firewall rule to allow access to specified ports, or to allow access between VMs on the same subnetwork.

Create firewall rules to allow access for such things as:

  • The default ports used by SAP NetWeaver, as documented in TCP/IP Ports 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 admin.
  • Communication between VMs in a 3-tier, scaleout, or high-availability configuration. For example, if you are deploying a 3-tier system, you will have at least 2 VMs in your subnetwork: the VM for SAP NetWeaver, and another VM for the database server. To enable communication between the two VMs, you must create a firewall rule to allow traffic that originates from the subnetwork.
  • Cloud Load Balancing health checks. For more information, see Create a firewall rule for the health checks.

To create the firewall rules for your project, see Creating firewall rules.

Creating a high-availability Linux cluster for SAP NetWeaver

The following instructions use a Terraform configuration file to create a SLES cluster with two SAP NetWeaver systems, a primary single-host SAP NetWeaver system on one VM instance and a standby SAP NetWeaver system on another VM instance in the same Compute Engine region.

You define configuration options for the SAP NetWeaver high-availability cluster in a Terraform configuration file.

  1. Open the Cloud Shell.

    Go to the Cloud Shell

  2. Download the sap_nw_ha.tf configuration file for the SAP NetWeaver high-availability cluster to your working directory:

    $ wget https://storage.googleapis.com/cloudsapdeploy/terraform/latest/terraform/sap_nw_ha/terraform/sap_nw_ha.tf
  3. Open the sap_nw_ha.tf file in the Cloud Shell code editor.

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

  4. In the sap_nw_ha.tf file, update the argument values by replacing the contents inside the double quotation marks with the values for your installation. The arguments are described in the following table.

    Argument Data type Description
    source String

    Specifies the location and version of the Terraform module to use during deployment.

    The DEPLOYMENT_TYPE.tf configuration file includes two instances of the source argument: one that is active and one that is included as a comment. The source argument that is active by default specifies latest as the module version. The second instance of the source argument, which by default is deactivated by a leading # character, specifies a timestamp that identifies a module version.

    If you need all of your deployments to use the same module version, then remove the leading # character from the source argument that specifies the version timestamp and add it to the source argument that specifies latest.

    project_id String Specify the ID of your Google Cloud project in which you are deploying this system.
    machine_type String Specify the type of Compute Engine virtual machine (VM) on which you need to run your SAP system. If you need a custom VM type, then 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.
    network String Specify the name of the network in which you need to create the load balancer that manages the VIP.

    If you are using a shared VPC network, you must add the ID of the host project as a parent directory of the network name. For example, HOST_PROJECT_ID/NETWORK_NAME.

    subnetwork String Specify the name of the subnetwork that you created in a previous step. If you are deploying to a shared VPC, then specify this value as SHARED_VPC_PROJECT_ID/SUBNETWORK. For example, myproject/network1.
    linux_image String Specify the name of the Linux operating system image on which you want to deploy your SAP system. For example, sles-15-sp3-sap. For the list of available operating system images, see the Images page in the Google Cloud console.
    linux_image_project String Specify the Google Cloud project that contains the image that you have specified for the argument linux_image. This project might be your own project or a Google Cloud image project. For a Compute Engine image, specify suse-sap-cloud. To find the image project for your operating system, see Operating system details.
    sap_primary_instance String Specify a name for the VM instance for the primary SAP NetWeaver system. This is your initial ASCS location. The name can contain lowercase letters, numbers, or hyphens and must not exceed 13 characters.
    sap_primary_zone String Specify a zone in which the primary SAP NetWeaver system is deployed. The primary and secondary zones must be in the same region.
    sap_secondary_instance String Specify a name for the VM instance for the secondary SAP NetWeaver system. This is your initial ERS location. The name can contain lowercase letters, numbers, or hyphens and must not exceed 13 characters.
    sap_secondary_zone String Specify a zone in which the secondary SAP NetWeaver system is deployed. The primary and secondary zones must be in the same region.
    nfs_path String Specify the NFS mount point for the shared file system. For example, 10.163.58.114:/ssd_nfs.
    sap_sid String Specify an SAP system ID. The ID must consist of three alpha-numeric characters and begin with a letter. All letters must be in uppercase.
    hc_firewall_rule_name String Optional. Specify a name for the health check firewall rule. The default value is SAP_SID-hc-allow.
    hc_network_tag String Optional. Specify one or more comma-separated network tags that you want to associate with your VM instances for the health check firewall rule. The default value is SAP_SID-hc-allow-tag.
    scs_inst_group_name String Optional. Specify a name for the ASCS instance group. The default value is SAP_SID-scs-ig.
    scs_hc_name String Optional. Specify a name for the ASCS health check. The default value is SAP_SID-scs-hc.
    scs_hc_port String Optional. Specify a port for the ASCS health check. To avoid clashing with other services, designate the port number for the ASCS health check in the private range, 49152-65535. The default value is 60000.
    scs_vip_address String Optional. Specify an unused IP address within the subnetwork specified on subnetwork earlier to use as the virtual IP address for the ASCS instance. If nothing is specified, the deployment scripts automatically select an unused IP address from the specified subnetwork.
    scs_vip_name String Optional. Specify a name for the ASCS virtual IP. The default value is SAP_SID-scs-vip.
    scs_backend_svc_name String Optional. Specify a name for the ASCS backend service. The default value is SAP_SID-scs-backend-svc.
    scs_forw_rule_name String Optional. Specify a name for the ASCS forwarding rule. The default value is SAP_SID-scs-fwd-rule.
    ers_inst_group_name String Optional. Specify a name for the ERS instance group. The default value is SAP_SID-ers-ig.
    ers_hc_name String Optional. Specify a name for the ERS health check. The default value is SAP_SID-ers-hc.
    ers_hc_port String Optional. Specify a port for the ERS health check. To avoid clashing with other services, designate the port number for ERS health check in the private range, 49152-65535. The default value is 60010.
    ers_vip_address String Optional. Specify an unused IP address within the subnetwork specified on subnetwork earlier to use as the virtual IP address for the ERS instance. If nothing is specified, the deployment scripts automatically select an unused IP address from the specified subnetwork.
    ers_vip_name String Optional. Specify a name for the ERS virtual IP. The default value is SAP_SID-ers-vip.
    ers_backend_svc_name String Optional. Specify a name for the ERS backend service. The default value is SAP_SID-ers-backend-svc.
    ers_forw_rule_name String Optional. Specify a name for the ERS forwarding rule. The default value is SAP_SID-ers-fwd-rule.
    usr_sap_size Integer Optional. Specify the size of the /usr/sap disk in GB. The minimum size is 8 GB. The default value is 8.
    sap_mnt_size Integer Optional. Specify the size of the /sapmnt disk in GB. The minimum size is 8 GB. The default value is 8.
    swap_size Integer Optional. Specify the size of the swap volume in GB. The minimum size is 8 GB. The default value is 8.
    sap_scs_instance_number String Optional. Specify the ASCS instance number. The sap_scs_instance_number must be a two-digit number. If you need to specify a single digit number, then add a 0 in front of the number. For example, 07. The default value is 00.
    sap_ers_instance_number String Optional. Specify the ERS instance number. The sap_ers_instance_number must be a two-digit number. If you need to specify a single digit number, then add a 0 in front of the number. For example, 07. The default value is 10.
    sap_nw_abap Boolean Optional. Specify whether you are deploying an ABAP stack or a Java stack of SAP NetWeaver. For a Java stack of SAP NetWeaver, specify false. The default value is true.
    pacemaker_cluster_name String Optional. Specify a name for the pacemaker cluster. The default value is SAP_SID-cluster.
    public_ip Boolean Optional. To create an ephemeral public IP address for the VM instances, set the public_ip to true. The default value is false.
    service_account String Optional. Specify the email address of a user-managed service account to be used by the host VMs and by the programs that run on the host VMs. For example, svc-acct-name@project-id.iam.gserviceaccount.com.

    If you specify this argument without a value, or omit it, then the installation script uses the Compute Engine default service account. For more information, see Identity and access management for SAP programs on Google Cloud.

    network_tags String Optional. Specify one or more comma-separated network tags that you want to associate with your VM instances for firewall or routing purposes.

    A network tag for the ILB components is automatically added to VM's Network tags.

    If public_ip = false and you do not specify a network tag, then make sure to provide another means of access to the internet.

    sap_deployment_debug Boolean Optional. Only when Cloud Customer Care asks you to enable debugging for your deployment, specify true, which makes the deployment generate verbose deployment logs. The default value is false.
    primary_reservation_name String Optional. To use a specific Compute Engine VM reservation for provisioning the VM instance that hosts your HA cluster's primary SAP HANA instance, specify the name of the reservation. By default, the installation script selects any available Compute Engine reservation based on the following conditions.

    For a reservation to be usable, regardless of whether you specify a name or the installation script selects it automatically, the reservation must be set with the following:

    • The specificReservationRequired option is set to true or, in the Google Cloud console, the Select specific reservation option is selected.
    • Some Compute Engine machine types support CPU platforms that are not covered by the SAP certification of the machine type. If the target reservation is for any of the following machine types, then the reservation must specify the minimum CPU platforms as indicated:
      • n1-highmem-32: Intel Broadwell
      • n1-highmem-64: Intel Broadwell
      • n1-highmem-96: Intel Skylake
      • m1-megamem-96: Intel Skylake
    • The minimum CPU platforms for all of the other machine types that are certified by SAP for use on Google Cloud conform to the SAP minimum CPU requirement.
    secondary_reservation_name String Optional. To use a specific Compute Engine VM reservation for provisioning the VM instance that hosts your HA cluster's secondary SAP HANA instance, specify the name of the reservation. By default, the installation script selects any available Compute Engine reservation based on the following conditions.

    For a reservation to be usable, regardless of whether you specify a name or the installation script selects it automatically, the reservation must be set with the following:

    • The specificReservationRequired option is set to true or, in the Google Cloud console, the Select specific reservation option is selected.
    • Some Compute Engine machine types support CPU platforms that are not covered by the SAP certification of the machine type. If the target reservation is for any of the following machine types, then the reservation must specify the minimum CPU platforms as indicated:
      • n1-highmem-32: Intel Broadwell
      • n1-highmem-64: Intel Broadwell
      • n1-highmem-96: Intel Skylake
      • m1-megamem-96: Intel Skylake
    • The minimum CPU platforms for all of the other machine types that are certified by SAP for use on Google Cloud conform to the SAP minimum CPU requirement.

    The following example shows a completed configuration file that defines a high-availability cluster for SAP NetWeaver. The cluster uses Internal TCP/UDP Load Balancing to manage the VIP.

    Terraform deploys the Google Cloud resources that are defined in the configuration file and then scripts take over to configure the operating system and configure the Linux HA cluster.

    For clarity, comments in the configuration file are omitted in the example.

       # ...
         module "sap_nw_ha" {
         source = "https://storage.googleapis.com/cloudsapdeploy/terraform/latest/terraform/sap_nw_ha/sap_nw_ha_module.zip"
       #
       # By default, this source file uses the latest release of the terraform module
       # for SAP on Google Cloud.  To fix your deployments to a specific release
       # of the module, comment out the source argument above and uncomment the source argument below.
       #
       # source = "https://storage.googleapis.com/cloudsapdeploy/terraform/202201240926/terraform/sap_nw_ha/sap_nw_ha_module.zip"
       #
       # ...
       #
       project_id = "example-project-123456"
       machine_type = "n2-highmem-32"
       network = "example-network"
       subnetwork = "example-subnet-us-central1"
       linux_image = "sles-15-sp3-sap"
       linux_image_project = "suse-sap-cloud"
    
       sap_primary_instance = "example-nw1"
       sap_primary_zone = "us-central1-a"
    
       sap_secondary_instance = "example-nw2"
       sap_secondary_zone = "us-central1-c"
    
       nfs_path = "10.223.55.130:/pr1_nw"
    
       sap_sid = "PR1"
       # ...
    }
  5. Initialize your current working directory and download the Terraform provider plugin and module files for Google Cloud:

    terraform init

    The terraform init command prepares your working directory for other Terraform commands.

    To force a refresh of the provider plugin and configuration files in your working directory, specify the --upgrade flag. If the --upgrade flag is omitted and you don't make any changes in your working directory, Terraform uses the locally cached copies, even if latest is specified in the source URL.

    terraform init --upgrade 
  6. Optionally, create the Terraform execution plan:

    terraform plan

    The terraform plan command shows the changes that are required by your current configuration. If you skip this step, the terraform apply command automatically creates a new plan and prompts you to approve it.

  7. Apply the execution plan:

    terraform apply

    When you are prompted to approve the actions, enter yes.

    The terraform apply command sets up the Google Cloud infrastructure and then hands control over to a script that configures the HA cluster according to the arguments defined in the terraform configuration file.

    While Terraform has control, status messages are written to the Cloud Shell. After the scripts are invoked, status messages are written to Logging and are viewable in the Google Cloud console, as described in Check the Logging logs.

    Time to completion can vary, but the entire process usually takes less than 30 minutes.

Verifying the deployment of your SAP NetWeaver HA system

Verifying an SAP NetWeaver HA cluster involves several different procedures:

  • Check the logs
  • Check the configuration of the VM

Check the logs

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

    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 NetWeaver requirements that are listed in the SAP NetWeaver planning guide.

      2. Open Cloud Shell.

        Go to Cloud Shell

      3. Go to your working directory and delete the deployment to clean up the VMs and persistent disks from the failed installation:

        terraform destroy

        When you are prompted to approve the action, enter yes.

      4. Rerun your deployment.

Check the configuration of the VM

  1. After the VM instances deploy 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. Ensure that you see output that includes the /usr/sap directories, such as /usr/sap/trans.

    example-nw1:~ # df -h
      Filesystem                             Size  Used Avail Use% Mounted on
      ...
      /dev/mapper/vg_usrsap-vol              8.0G   41M  8.0G   1% /usr/sap
      /dev/mapper/vg_sapmnt-vol              8.0G   41M  8.0G   1% /sapmnt
      10.233.55.130:/pr1_nw_hdd/sapmntPR1   1007G   76M  956G   1% /sapmnt/PR1
      10.223.55.130:/pr1_nw/usrsaptrans     1007G     0  956G   0% /usr/sap/trans
      10.223.55.130:/pr1_nw/usrsapPR1SYS    1007G     0  956G   0% /usr/sap/PR1/SYS
      10.223.55.130:/pr1_nw/usrsapPR1ASCS00 1007G     0  956G   0% /usr/sap/PR1/ASCS00
      ...
      

  4. Check the status of the new cluster by entering the status command: crm status

    You should see results similar to the following the example, in which both VM instances are started and example-nw1 is the active primary instance:

    example-nw1:~ # crm status
    Cluster Summary:
      * Stack: corosync
      * Current DC: example-nw1 (version 2.0.4+20200616.2deceaa3a-3.6.1-2.0.4+20200616.2deceaa3a) - partition with quorum
      * Last updated: Fri Jun 18 05:47:48 2021
      * Last change:  Fri Jun 18 05:41:32 2021 by root via cibadmin on example-nw1
      * 2 nodes configured
      * 8 resource instances configured
    Node List:
      * Online: [ example-nw1 example-nw2 ]
    Full List of Resources:
      * fence-PR1-example-nw1     (stonith:fence_gce):           Started example-nw2
      * fence-PR1-example-nw2     (stonith:fence_gce):           Started example-nw1
      * file-system-PR1-ASCS00    (ocf::heartbeat:Filesystem):      Started example-nw1
      * file-system-PR1-ERS10     (ocf::heartbeat:Filesystem):      Started example-nw2
      * health-check-PR1-ASCS00   (ocf::heartbeat:anything):        Started example-nw1
      * health-check-PR1-ERS10    (ocf::heartbeat:anything):        Started example-nw2
      * vip-PR1-ASCS00      (ocf::heartbeat:IPaddr2):             Started example-nw1
      * vip-PR1-ERS10       (ocf::heartbeat:IPaddr2):             Started example-nw2

  5. Test the ASCS and ERS load balancer setup by using the socat utility. On each VM instance, start a socat process that returns its own hostname:

    # socat TCP-LISTEN:80,bind=0.0.0.0,fork,reuseaddr,crlf SYSTEM:"echo HTTP/1.0 200; echo Content-Type\: text/plain; echo; echo $(hostname)" & 

If any of the validation steps show that the installation failed:

  1. Resolve the errors.

  2. Open Cloud Shell.

    Go to Cloud Shell

  3. Go to the directory that contains the Terraform configuration file.

  4. Delete the deployment:

    terraform destroy

    When you are prompted to approve the action, enter yes.

  5. Rerun your deployment.

Validating your installation of the monitoring agent

After you have deployed a VM and installed your SAP system, validate that Google's monitoring agent is functioning properly with SAP's enhanced monitoring.

Verifying that Google's monitoring agent is running

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

  1. Establish an SSH connection with your host VM.

  2. Issue the following command:

    sudo systemctl status google-sapnetweavermonitoring-agent 

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

    google-sapnetweavermonitoring-agent.service - Google Cloud monitoring agent for SAP NetWeaver
    Loaded: loaded (/usr/lib/systemd/system/google-sapnetweavermonitoring-agent.service; enabled; vendor preset: disabled)
    Active:  active (running)  since Thu 2021-09-02 07:21:42 UTC; 742ms ago
    Main PID: 10723 (java)
    Tasks: 26 (limit: 512)
    CGroup: /system.slice/google-sapnetweavermonitoring-agent.service
           └─10723 /usr/sap/google-sapnetweavermonitoring-agent/jre/bin/java -Xms32m -Xmx64m -cp /usr/sap/google-sapnetweavermonitoring-age...
    

If the monitoring agent isn't running, then see the Operations Guide section about restarting Google's monitoring agent.

Verifying that SAP Host Agent is receiving metrics

To verify that the infrastructure metrics are collected 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

Install ASCS and ERS

The following section covers only the requirements and recommendations that are specific to installing SAP NetWeaver on Google Cloud.

For complete installation instructions, see the SAP NetWeaver documentation.

Prepare for installation

To ensure consistency across the cluster and simplify installation, before you install the SAP NetWeaver ASCS and ERS components, define the users, groups, and permissions and put the secondary server in standby mode.

  1. Take the cluster out of maintenance mode:

    # crm configure property maintenance-mode="false"

  2. On both servers as root, enter the following commands, specifying the user and group IDs that are appropriate for your environment:

    # groupadd -g GID_SAPINST sapinst
    # groupadd -g GID_SAPSYS sapsys
    # useradd -u UID_SIDADM SID_LCadm -g sapsys
    # usermod -a -G sapinst SID_LCadm
    # useradd -u UID_SAPADM sapadm -g sapinst
    
    # chown SID_LCadm:sapsys /usr/sap/SID/SYS
    # chown SID_LCadm:sapsys /sapmnt/SID -R
    # chown SID_LCadm:sapsys /usr/sap/trans -R
    # chown SID_LCadm:sapsys /usr/sap/SID/SYS -R
    # chown SID_LCadm:sapsys /usr/sap/SID -R

    Replace the following:

    • GID_SAPINST: specify the Linux group ID for the SAP provisioning tool.
    • GID_SAPSYS: specify the Linux group ID for the SAPSYS user.
    • UID_SIDADM: specify the Linux user ID for the administrator of the SAP system (SID).
    • SID_LC: specify the system ID (SID). Use lowercase for any letters.
    • UID_SAPADM: specify the user ID for the SAP Host Agent.
    • SID: specify the system ID (SID). Use uppercase for any letters.

    For example, the following shows a practical GID and UID numbering scheme:

    Group sapinst      1001
    Group sapsys       1002
    Group dbhshm       1003
    
    User  en2adm       2001
    User  sapadm       2002
    User  dbhadm       2003

Install the ASCS component

  1. On the secondary server, enter the following command to put the secondary server in standby mode:

    # crm_standby -v on -N ${HOSTNAME};

    Putting the secondary server in standby mode consolidates all of the cluster resources on the primary server, which simplifies installation.

  2. Confirm that the secondary server is in standby mode:

    # crm status

    You should see output similar to the following example:

    Stack: corosync
     Current DC: nw-ha-vm-1 (version 1.1.24+20201209.8f22be2ae-3.12.1-1.1.24+20201209.8f22be2ae) - partition with quorum
     Last updated: Thu May 27 17:45:16 2021
     Last change: Thu May 27 17:45:09 2021 by root via crm_attribute on nw-ha-vm-2
    
     2 nodes configured
     8 resource instances configured
    
     Node nw-ha-vm-2: standby
     Online: [ nw-ha-vm-1 ]
    
     Full list of resources:
    
      fencing-rsc-nw-aha-vm-1        (stonith:fence_gce):    Stopped
      fencing-rsc-nw-aha-vm-2        (stonith:fence_gce):    Started nw-ha-vm-1
      filesystem-rsc-nw-aha-scs      (ocf::heartbeat:Filesystem):    Started nw-ha-vm-1
      filesystem-rsc-nw-aha-ers      (ocf::heartbeat:Filesystem):    Started nw-ha-vm-1
      health-check-rsc-nw-ha-scs     (ocf::heartbeat:anything):      Started nw-ha-vm-1
      health-check-rsc-nw-ha-ers     (ocf::heartbeat:anything):      Started nw-ha-vm-1
      vip-rsc-nw-aha-scs     (ocf::heartbeat:IPaddr2):       Started nw-ha-vm-1
      vip-rsc-nw-aha-ers     (ocf::heartbeat:IPaddr2):       Started nw-ha-vm-1
    
  3. On the primary server as the root user, change your directory to a temporary installation directory, such as /tmp, to install the ASCS instance by running the SAP Software Provisioning Manager (SWPM).

    • To access the web interface of SWPM, you need the password for the root user. If your IT policy does not allow the SAP administrator to have access to the root password, you can use the SAPINST_REMOTE_ACCESS_USER.

    • When you start SWPM, use the SAPINST_USE_HOSTNAME parameter to specify the virtual host name that you defined for the ASCS VIP address in the /etc/hosts file.

      For example:

      cd /tmp; /mnt/nfs/install/SWPM/sapinst SAPINST_USE_HOSTNAME=vh-aha-scs
    • On the final SWPM confirmation page, ensure that the virtual host name is correct.

  4. After the configuration completes, take the secondary VM out of standby mode:

    # crm_standby -v off -N ${HOSTNAME}; # On SECONDARY

Install the ERS component

  1. On the primary server as root or SID_LCadm, stop the ASCS service.

    # su - SID_LCadm -c "sapcontrol -nr ASCS_INSTANCE_NUMBER -function Stop"
    # su - SID_LCadm -c "sapcontrol -nr ASCS_INSTANCE_NUMBER -function StopService"
  2. On the primary server, enter the following command to put the primary server in standby mode:

    # crm_standby -v on -N ${HOSTNAME};

    Putting the primary server in standby mode consolidates all of the cluster resources on the secondary server, which simplifies installation.

  3. Confirm that the primary server is in standby mode:

    # crm status

  4. On the secondary server as the root user, change your directory to a temporary installation directory, such as /tmp, to install the ERS instance by running the SAP Software Provisioning Manager (SWPM).

    • Use the same user and password to access SWPM that you used when you installed the ASCS component.

    • When you start SWPM, use the SAPINST_USE_HOSTNAME parameter to specify the virtual host name that you defined for the ERS VIP address in the /etc/hosts file.

      For example:

      cd /tmp; /mnt/nfs/install/SWPM/sapinst SAPINST_USE_HOSTNAME=vh-aha-ers
    • On the final SWPM confirmation page, ensure that the virtual host name is correct.

  5. Take the primary VM out of standby to have both active:

    # crm_standby -v off -N ${HOSTNAME};

Configure the SAP services

You need to confirm that the services are configured correctly, check the settings in the ASCS and ERS profiles, and add the SID_LCadm user to the haclient user group.

Confirm the SAP service entries

  1. On both servers, confirm that /usr/sap/sapservices contains entries for both the ASCS and ERS services. You can add any missing entries by using the sapstartsrv command with options pf=PROFILE_OF_THE_SAP_INSTANCE and -reg. For example:

    # LD_LIBRARY_PATH=/usr/sap/hostctrl/exe:$LD_LIBRARY_PATH; export LD_LIBRARY_PATH
    /usr/sap/hostctrl/exe/sapstartsrv \
     pf=/usr/sap/SID_UC/SYS/profile/SID_UC_ERSERS_INSTANCE_NUMBER_ERS_VIRTUAL_HOST_NAME \
     -reg
    /usr/sap/hostctrl/exe/sapstartsrv \
     pf=/usr/sap/SID_UC/SYS/profile/SID_UC_ASCSASCS_INSTANCE_NUMBER_ASCS_VIRTUAL_HOST_NAME \
     -reg

Stop the SAP services

  1. On the secondary server, stop the ERS service:

    # su - SID_LCadm -c "sapcontrol -nr ERS_INSTANCE_NUMBER -function Stop"
    # su - SID_LCadm -c "sapcontrol -nr ERS_INSTANCE_NUMBER -function StopService"
  2. On each server, validate that all services are stopped:

    # su - SID_LCadm -c "sapcontrol -nr ASCS_INSTANCE_NUMBER -function GetSystemInstanceList"
    # su - SID_LCadm -c "sapcontrol -nr ERS_INSTANCE_NUMBER -function GetSystemInstanceList"

    You should see output similar to the following example:

    GetSystemInstanceList
    FAIL: NIECONN_REFUSED (Connection refused), NiRawConnect failed in plugin_fopen()

Edit the ASCS and ERS profiles

  1. On either server, switch to the profile directory, by using either of the following commands:

    # cd /usr/sap/SID_UC/SYS/profile
    # cd /sapmnt/SID_UC/profile
  2. If necessary, you can find the files names of your ASCS and ERS profiles by listing the files in the profile directory or use the following formats:

    SID_ASCSASCS_INSTANCE_NUMBER_ASCS_VIRTUAL_HOST_NAME
    SID_ERSERS_INSTANCE_NUMBER_ERS_VIRTUAL_HOST_NAME
  3. Enable the package sap-suse-cluster-connector by adding the following lines to the profiles ASCS and ERS instance profiles:

    #-----------------------------------------------------------------------
    # SUSE HA library
    #-----------------------------------------------------------------------
    service/halib = $(DIR_CT_RUN)/saphascriptco.so
    service/halib_cluster_connector = /usr/bin/sap_suse_cluster_connector
    
  4. If you are using ENSA1, enable the keepalive function by setting the following in the ASCS profile:

    enque/encni/set_so_keepalive = true

    For more information, see SAP Note 1410736 - TCP/IP: setting keepalive interval.

  5. If necessary, edit the ASCS and ERS profiles to change the startup behavior of the Enqueue Server and the Enqueue Replication Server.

    ENSA1

    In the "Start SAP enqueue server" section of the ASCS profile, if you see Restart_Program_NN, change "Restart" to "Start", as shown in the following example.

    Start_Program_01 = local $(_EN) pf=$(_PF)

    In the "Start enqueue replication server" section of the ERS profile, if you see Restart_Program_NN, change "Restart" to "Start", as shown in the following example.

    Start_Program_00 = local $(_ER) pf=$(_PFL) NR=$(SCSID)

    ENSA2

    In the "Start SAP enqueue server" section of the ASCS profile, if you see Restart_Program_NN, change "Restart" to "Start", as shown in the following example.

    Start_Program_01 = local $(_ENQ) pf=$(_PF)

    In the "Start enqueue replicator" section of the ERS profile, if you see Restart_Program_NN, change "Restart" to "Start", as shown in the following example.

    Start_Program_00 = local $(_ENQR) pf=$(_PF) ...

Add the sidadm user to the haclient user group

When you installed the sap-suse-cluster-connector, the installation created an haclient user group. To enable the SID_LCadm user to work with the cluster, add it to the haclient user group.

  1. On both servers, add the SID_LCadm user to the haclient user group:

    # usermod -aG haclient SID_LCadm

Configure the cluster resources for ASCS and ERS

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

    # crm configure property maintenance-mode="true"
  2. Confirm that the custer is in maintenance mode:

    # crm status

    If the cluster is in maintenance mode, the status includes the following lines:

                  *** Resource management is DISABLED ***
    The cluster will not attempt to start, stop or recover services
  3. Create the cluster resources for the ASCS and ERS services:

    ENSA1

    • Create the cluster resource for the ASCS instance. The value of InstanceName is the name of the instance profile that SWPM generated when you installed ASCS.

      # crm configure primitive ASCS_INSTANCE_RSC_NAME SAPInstance \
        operations \$id=ASCS_INSTANCE_RSC_OPERATIONS_NAME \
        op monitor interval=11 timeout=60 on-fail=restart \
        params InstanceName=SID_UC_ASCSASCS_INSTANCE_NUMBER_ASCS_VIRTUAL_HOST_NAME \
           START_PROFILE="/PATH_TO_PROFILE/SID_UC_ASCSASCS_INSTANCE_NUMBER_ASCS_VIRTUAL_HOST_NAME" \
           AUTOMATIC_RECOVER=false \
        meta resource-stickiness=5000 failure-timeout=60 \
           migration-threshold=1 priority=10
    • Create the cluster resource for the ERS instance. The value of InstanceName is the name of the instance profile that SWPM generated when you installed ERS. The parameter IS_ERS=true tells Pacemaker to set the runsersSID_UC flag to 1 on the node where ERS is active.

      # crm configure primitive ERS_INSTANCE_RSC_NAME SAPInstance \
        operations \$id=ERS_INSTANCE_RSC_OPERATIONS_NAME \
        op monitor interval=11 timeout=60 on-fail=restart \
        params InstanceName=SID_UC_ERSERS_INSTANCE_NUMBER_ERS_VIRTUAL_HOST_NAME \
           START_PROFILE="/PATH_TO_PROFILE/SID_UC_ERSERS_INSTANCE_NUMBER_ERS_VIRTUAL_HOST_NAME" \
           AUTOMATIC_RECOVER=false IS_ERS=true \
        meta priority=1000

    ENSA2

    • Create the cluster resource for the ASCS instance. The value of InstanceName is the name of the instance profile that SWPM generated when you installed ASCS.

      # crm configure primitive ASCS_INSTANCE_RSC_NAME SAPInstance \
        operations \$id=ASCS_INSTANCE_RSC_OPERATIONS_NAME \
        op monitor interval=11 timeout=60 on-fail=restart \
        params InstanceName=SID_UC_ASCSASCS_INSTANCE_NUMBER_ASCS_VIRTUAL_HOST_NAME \
           START_PROFILE="/PATH_TO_PROFILE/SID_UC_ASCSASCS_INSTANCE_NUMBER_ASCS_VIRTUAL_HOST_NAME" \
           AUTOMATIC_RECOVER=false \
        meta resource-stickiness=5000 failure-timeout=60
    • Create the cluster resource for the ERS instance. The value of InstanceName is the name of the instance profile that SWPM generated when you installed ERS.

      # crm configure primitive ERS_INSTANCE_RSC_NAME SAPInstance \
        operations \$id=ERS_INSTANCE_RSC_OPERATIONS_NAME \
        op monitor interval=11 timeout=60 on-fail=restart \
        params InstanceName=SID_UC_ERSERS_INSTANCE_NUMBER_ERS_VIRTUAL_HOST_NAME  \
           START_PROFILE="/PATH_TO_PROFILE/SID_UC_ERSERS_INSTANCE_NUMBER_ERS_VIRTUAL_HOST_NAME" \
           AUTOMATIC_RECOVER=false IS_ERS=true

Configure the resource groups and location constraints

  1. Group the ASCS and ERS resources. You can display the names of all your previously defined resources by entering the command crm resource status:

    # crm configure group ASCS_RSC_GROUP_NAME ASCS_FILE_SYSTEM_RSC_NAME \
      ASCS_HEALTH_CHECK_RSC_NAME ASCS_VIP_RSC_NAME \
      ASCS_INSTANCE_RSC_NAME \
      meta resource-stickiness=3000

    Replace the following:

    • ASCS_RESOURCE_GROUP: specify a unique group name for the ASCS cluster resources. You can ensure uniqueness by using a convention like "SID_ASCSinstance number_group". For example, nw1_ASCS00_group.
    • ASCS_FILE_SYSTEM_RESOURCE: specify the name of the cluster resource that you defined for the ASCS file system earlier.
    • ASCS_HEALTH_CHECK_RESOURCE: specify the name of the cluster resource that you defined for the ASCS health check earlier.
    • ASCS_VIP_RESOURCE: specify the name of the cluster resource that you defined for the ASCS VIP earlier.
    • ASCS_INSTANCE_RESOURCE: specify the name of the cluster resource that you defined for the ASCS instance earlier.
    # crm configure group ERS_RSC_GROUP_NAME ERS_FILE_SYSTEM_RSC_NAME \
      ERS_HEALTH_CHECK_RSC_NAME ERS_VIP_RSC_NAME \
      ERS_INSTANCE_RSC_NAME

    Replace the following:

    • ERS_RESOURCE_GROUP: specify a unique group name for the ERS cluster resources. You can ensure uniqueness by using a convention like "SID_ERSinstance number_group". For example, nw1_ERS10_group.
    • ERS_FILE_SYSTEM_RESOURCE: specify the name of the cluster resource that you defined for the ERS file system earlier.
    • ERS_HEALTH_CHECK_RESOURCE: specify the name of the cluster resource that you defined for the ERS health check earlier.
    • ERS_VIP_RESOURCE: specify the name of the cluster resource that you defined for the ERS VIP earlier.
    • ERS_INSTANCE_RESOURCE: specify the name of the cluster resource that you defined for the ERS instance earlier.
  2. Create the colocation constraints:

    ENSA1

    1. Create a colocation constraint that prevents the ASCS resources from running on the same server as the ERS resources:

      # crm configure colocation PREVENT_ASCS_ERS_COLOC -5000: ERS_RSC_GROUP_NAME ASCS_RSC_GROUP_NAME
    2. Configure ASCS to failover to the server where ERS is running, as determined by the flag runsersSID_UC being equal to 1:

      # crm configure location LOC_ASCS_SID_FAILOVER_TO_ERS ASCS_INSTANCE_RSC_NAME \
      rule 2000: runs_ers_SID_UC eq 1
    3. Configure ASCS to start before ERS moves to the other server after a failover:

      # crm configure order ORD_SAP_SID_FIRST_START_ASCS \
       Optional: ASCS_INSTANCE_RSC_NAME:start \
       ERS_INSTANCE_RSC_NAME:stop symmetrical=false

    ENSA2

    1. Create a colocation constraint that prevents the ASCS resources from running on the same server as the ERS resources:

      # crm configure colocation PREVENT_ASCS_ERS_COLOC -5000: ERS_RSC_GROUP_NAME ASCS_RSC_GROUP_NAME
    2. Configure ASCS to start before ERS moves to the other server after a failover:

      # crm configure order ORD_SAP_SID_FIRST_START_ASCS \
       Optional: ASCS_INSTANCE_RSC_NAME:start \
       ERS_INSTANCE_RSC_NAME:stop symmetrical=false
  3. Disable maintenance mode.

    # crm configure property maintenance-mode="false"
  4. Check the configuration of the groups, colocation constraints, and ordering:

    # crm config show

    The output should include lines similar to those in the following example:

    ENSA1

    group ers-aha-rsc-group-name filesystem-rsc-nw-aha-ers health-check-rsc-nw-ha-ers vip-rsc-nw-aha-ers ers-aha-instance-rsc-name
    group scs-aha-rsc-group-name filesystem-rsc-nw-aha-scs health-check-rsc-nw-ha-scs vip-rsc-nw-aha-scs scs-aha-instance-rsc-name \
            meta resource-stickiness=3000
    colocation prevent-aha-scs-ers-coloc -5000: ers-aha-rsc-group-name scs-aha-rsc-group-name
    location fencing-rsc-nw-aha-vm-1-loc fencing-rsc-nw-aha-vm-1 -inf: nw-ha-vm-1
    location fencing-rsc-nw-aha-vm-2-loc fencing-rsc-nw-aha-vm-2 -inf: nw-ha-vm-2
    location loc-sap-AHA-failover-to-ers scs-aha-instance-rsc-name \
            rule 2000: runs_ers_AHA eq 1

    ENSA2

    group ers-aha-rsc-group-name filesystem-rsc-nw-aha-ers health-check-rsc-nw-ha-ers vip-rsc-nw-aha-ers ers-aha-instance-rsc-name
    group scs-aha-rsc-group-name filesystem-rsc-nw-aha-scs health-check-rsc-nw-ha-scs vip-rsc-nw-aha-scs scs-aha-instance-rsc-name \
            meta resource-stickiness=3000
    location fencing-location-nw-aha-vm-1 fencing-rsc-nw-aha-vm-1 -inf: nw-ha-vm-1
    location fencing-location-nw-aha-vm-2 fencing-rsc-nw-aha-vm-2 -inf: nw-ha-vm-2
    order ord-sap-AHA-first-start-ascs Optional: scs-aha-instance-rsc-name:start ers-aha-instance-rsc-name:stop symmetrical=false
    colocation prevent-aha-scs-ers-coloc -5000: ers-aha-rsc-group-name scs-aha-rsc-group-name

Validate and test your cluster

This section shows you how to run the following tests:

  • Check for configuration errors
  • Confirm that the ASCS and ERS resources switch servers correctly during failovers
  • Confirm that locks are retained
  • Simulate a Compute Engine maintenance event to make sure that live migration doesn't trigger a failover

Check the cluster configuration

  1. As root on either server, check which nodes your resources are running on:

    # crm status

    In the following example, the ASCS resources are running on the nw-ha-vm-1 server and the ERS resources are running on the nw-ha-vm-2 server.

    Cluster Summary:
      * Stack: corosync
      * Current DC: nw-ha-vm-2 (version 2.0.4+20200616.2deceaa3a-3.3.1-2.0.4+20200616.2deceaa3a) - partition with quorum
      * Last updated: Thu May 20 16:58:46 2021
      * Last change:  Thu May 20 16:57:31 2021 by ahaadm via crm_resource on nw-ha-vm-2
      * 2 nodes configured
      * 10 resource instances configured
    
    Node List:
      * Online: [ nw-ha-vm-1 nw-ha-vm-2 ]
    
    Active Resources:
      * fencing-rsc-nw-aha-vm-1     (stonith:fence_gce):     Started nw-ha-vm-2
      * fencing-rsc-nw-aha-vm-2     (stonith:fence_gce):     Started nw-ha-vm-1
      * Resource Group: ascs-aha-rsc-group-name:
        * filesystem-rsc-nw-aha-ascs (ocf::heartbeat:Filesystem):     Started nw-ha-vm-1
        * health-check-rsc-nw-ha-ascs        (ocf::heartbeat:anything):       Started nw-ha-vm-1
        * vip-rsc-nw-aha-ascs        (ocf::heartbeat:IPaddr2):        Started nw-ha-vm-1
        * ascs-aha-instance-rsc-name (ocf::heartbeat:SAPInstance):    Started nw-ha-vm-1
      * Resource Group: ers-aha-rsc-group-name:
        * filesystem-rsc-nw-aha-ers (ocf::heartbeat:Filesystem):     Started nw-ha-vm-2
        * health-check-rsc-nw-ha-ers        (ocf::heartbeat:anything):       Started nw-ha-vm-2
        * vip-rsc-nw-aha-ers        (ocf::heartbeat:IPaddr2):        Started nw-ha-vm-2
        * ers-aha-instance-rsc-name (ocf::heartbeat:SAPInstance):    Started nw-ha-vm-2
  2. Switch to the SID_LCadm user:

    # su - SID_LCadm
  3. Check the cluster configuration. For INSTANCE_NUMBER, specify the instance number of the ASCS or ERS instance that is active on the server where you are entering the command:

    > sapcontrol -nr INSTANCE_NUMBER -function HAGetFailoverConfig

    HAActive should be TRUE, as shown in the following example:

    20.05.2021 01:33:25
    HAGetFailoverConfig
    OK
    HAActive: TRUE
    HAProductVersion: SUSE Linux Enterprise Server for SAP Applications 15 SP2
    HASAPInterfaceVersion: SUSE Linux Enterprise Server for SAP Applications 15 SP2 (sap_suse_cluster_connector 3.1.2)
    HADocumentation: https://www.suse.com/products/sles-for-sap/resource-library/sap-best-practices/
    HAActiveNode: nw-ha-vm-1
    HANodes: nw-ha-vm-1, nw-ha-vm-2

  4. As SID_LCadm, check for errors in the configuration:

    > sapcontrol -nr INSTANCE_NUMBER -function HACheckConfig

    You should see output similar to the following example:

    20.05.2021 01:37:19
    HACheckConfig
    OK
    state, category, description, comment
    SUCCESS, SAP CONFIGURATION, Redundant ABAP instance configuration, 0 ABAP instances detected
    SUCCESS, SAP CONFIGURATION, Redundant Java instance configuration, 0 Java instances detected
    SUCCESS, SAP CONFIGURATION, Enqueue separation, All Enqueue server separated from application server
    SUCCESS, SAP CONFIGURATION, MessageServer separation, All MessageServer separated from application server
    SUCCESS, SAP STATE, SCS instance running, SCS instance status ok
    SUCCESS, SAP CONFIGURATION, SAPInstance RA sufficient version (vh-ascs-aha_AHA_00), SAPInstance includes is-ers patch
    SUCCESS, SAP CONFIGURATION, Enqueue replication (vh-ascs-aha_AHA_00), Enqueue replication enabled
    SUCCESS, SAP STATE, Enqueue replication state (vh-ascs-aha_AHA_00), Enqueue replication active

  5. On the server where ASCS is active, as SID_LCadm, simulate a failover:

    > sapcontrol -nr ASCS_INSTANCE_NUMBER -function HAFailoverToNode ""
  6. As root, if you follow the failover by using crm_mon, you should see ASCS move to the other server, ERS stop on that server, and then ERS move to the server that ASCS used to be running on.

Simulate a 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.

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

  • shutdown -r (on the active node)
  • ip link set eth0 down
  • echo c > /proc/sysrq-trigger

These instructions use ip link set eth0 down to take the network interface offline, because it validates both failover as well as fencing.

  1. Backup your system.

  2. As root on the host with the active SCS instance, take the network interface offline:

    # ip link set eth0 down
  3. Reconnect to either host using SSH and change to the root user.

  4. 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.

    Cluster Summary:
    * Stack: corosync
    * Current DC: nw-ha-vm-2 (version 2.0.4+20200616.2deceaa3a-3.3.1-2.0.4+20200616.2deceaa3a) - partition with quorum
    * Last updated: Fri May 21 22:31:32 2021
    * Last change:  Thu May 20 20:36:36 2021 by ahaadm via crm_resource on nw-ha-vm-1
    * 2 nodes configured
    * 10 resource instances configured
    
    Node List:
    * Online: [ nw-ha-vm-1 nw-ha-vm-2 ]
    
    Full List of Resources:
    * fencing-rsc-nw-aha-vm-1     (stonith:fence_gce):     Started nw-ha-vm-2
    * fencing-rsc-nw-aha-vm-2     (stonith:fence_gce):     Started nw-ha-vm-1
    * Resource Group: scs-aha-rsc-group-name:
      * filesystem-rsc-nw-aha-scs (ocf::heartbeat:Filesystem):     Started nw-ha-vm-2
      * health-check-rsc-nw-ha-scs        (ocf::heartbeat:anything):       Started nw-ha-vm-2
      * vip-rsc-nw-aha-scs        (ocf::heartbeat:IPaddr2):        Started nw-ha-vm-2
      * scs-aha-instance-rsc-name (ocf::heartbeat:SAPInstance):    Started nw-ha-vm-2
    * Resource Group: ers-aha-rsc-group-name:
      * filesystem-rsc-nw-aha-ers (ocf::heartbeat:Filesystem):     Started nw-ha-vm-1
      * health-check-rsc-nw-ha-ers        (ocf::heartbeat:anything):       Started nw-ha-vm-1
      * vip-rsc-nw-aha-ers        (ocf::heartbeat:IPaddr2):        Started nw-ha-vm-1
      * ers-aha-instance-rsc-name (ocf::heartbeat:SAPInstance):    Started nw-ha-vm-1

Confirm lock entries are retained

To confirm lock entries are preserved across a failover, first select the tab for your version of the Enqueue Server and the follow the procedure to generate lock entries, simulate a failover, and confirm that the lock entries are retained after ASCS is activated again.

ENSA1

  1. As SID_LCadm, on the server where ERS is active, generate lock entries by using the enqt program:

    > enqt pf=/PATH_TO_PROFILE/SID_ERSERS_INSTANCE_NUMBER_ERS_VIRTUAL_HOST_NAME 11 NUMBER_OF_LOCKS
  2. As SID_LCadm, on the server where ASCS is active, verify that the lock entries are registered:

    > sapcontrol -nr ASCS_INSTANCE_NUMBER -function EnqGetStatistic | grep locks_now

    If you created 10 locks, you should see output similar to the following example:

    locks_now: 10
  3. As SID_LCadm, on the server where ERS is active, start the monitoring function, OpCode=20, of the enqt program:

    > enqt pf=/PATH_TO_PROFILE/SID_ERSERS_INSTANCE_NUMBER_ERS_VIRTUAL_HOST_NAME 20 1 1 9999

    For example:

    > enqt pf=/sapmnt/AHA/profile/AHA_ERS10_vh-ers-aha 20 1 1 9999
  4. Where ASCS is active, reboot the server.

    On the monitoring server, by the time Pacemaker stops ERS to move it to the other server, you should see output similar to the following.

    Number of selected entries: 10
    Number of selected entries: 10
    Number of selected entries: 10
    Number of selected entries: 10
    Number of selected entries: 10
  5. When the enqt monitor stops, exit the monitor by entering Ctrl + c.

  6. Optionally, as root on either server, monitor the cluster failover:

    # crm_mon
  7. As SID_LCadm, after you confirm the locks were retained, release the locks:

    > enqt pf=/PATH_TO_PROFILE/SID_ERSERS_INSTANCE_NUMBER_ERS_VIRTUAL_HOST_NAME 12 NUMBER_OF_LOCKS
  8. As SID_LCadm, on the server where ASCS is active, verify that the lock entries are removed:

    > sapcontrol -nr ASCS_INSTANCE_NUMBER -function EnqGetStatistic | grep locks_now

ENSA2

  1. As SID_LCadm, on the server where ASCS is active, generate lock entries by using the enq_adm program:

    > enq_admin --set_locks=NUMBER_OF_LOCKS:X:DIAG::TAB:%u pf=/PATH_TO_PROFILE/SID_ASCSASCS_INSTANCE_NUMBER_ASCS_VIRTUAL_HOST_NAME
  2. As SID_LCadm, on the server where ASCS is active, verify that the lock entries are registered:

    > sapcontrol -nr ASCS_INSTANCE_NUMBER -function EnqGetStatistic | grep locks_now

    If you created 10 locks, you should see output similar to the following example:

    locks_now: 10
  3. Where ERS is active, confirm that the lock entries were replicated:

    > sapcontrol -nr ERS_INSTANCE_NUMBER -function EnqGetStatistic | grep locks_now

    The number of returned locks should be the same as on the ASCS instance.

  4. Where ASCS is active, reboot the server.

  5. Optionally, as root on either server, monitor the cluster failover:

    # crm_mon
  6. As SID_LCadm, on the server where ASCS was restarted, verify that the lock entries were retained:

    > sapcontrol -nr ASCS_INSTANCE_NUMBER -function EnqGetStatistic | grep locks_now
  7. As SID_LCadm, on the server where ERS is active, after you confirm the locks were retained, release the locks:

    > enq_admin --release_locks=NUMBER_OF_LOCKS:X:DIAG::TAB:%u pf=/PATH_TO_PROFILE/SID_ERSERS_INSTANCE_NUMBER_ERS_VIRTUAL_HOST_NAME
  8. As SID_LCadm, on the server where ASCS is active, verify that the lock entries are removed:

    > sapcontrol -nr ASCS_INSTANCE_NUMBER -function EnqGetStatistic | grep locks_now

    You should see output similar to the following example:

    locks_now: 0

Simulate a Compute Engine maintenance event

Simulate a Compute Engine maintenance event to make sure that live migration does not trigger a failover.

The timeout and interval values that are used in these instructions account for the duration of live migrations. If you use shorter values in your cluster configuration, the risk that live migration might trigger a failover is greater.

To test the tolerance of your cluster for live migration:

  1. On the primary node, trigger a simulated maintenance event by using following gcloud CLI command:

    # gcloud compute instances simulate-maintenance-event PRIMARY_VM_NAME
  2. Confirm that the primary node does not change:

    # crm status

Troubleshooting

To troubleshoot problems with high-availability configurations for SAP NetWeaver, see Troubleshooting high-availability configurations for SAP.

Collect diagnostic information for SAP NetWeaver high-availability clusters

If you need help resolving a problem with high-availability clusters for SAP NetWeaver, gather the required diagnostic information and contact Cloud Customer Care.

To collect diagnostic information, see High-availability clusters on SLES diagnostic information.

Support

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

Performing post-deployment tasks

Before using your SAP NetWeaver system, we recommend that you backup your new SAP NetWeaver HA system.

For more information, see SAP NetWeaver operations guide.

What's next

For more information high-availability, SAP NetWeaver, and Google Cloud, see the following resources: