Enabling and disabling high availability on an instance

MySQL | PostgreSQL | SQL Server

This page describes how to configure an instance for high availability.

You can configure an instance for high availability when you create the instance, or you can enable high availability on an existing instance.

For more information about high availability, see Overview of the high availability Configuration.

The legacy configuration for high availability used a failover replica instance. The new configuration does not use a failover replica. Instead, it uses Google's regional persistent disks, which synchronously replicate data at the block-level between two zones in a region. If you have an existing MySQL instance that uses the legacy high availability, you can update your configuration to use the current version. For other procedures related the legacy high availability configuration, see Legacy configuration for high availability.

Creating a new instance configured for high availability

When you create an instance and configure it for high availability, Cloud SQL creates it as a regional instance.

To create an instance configured for high availability:

Console

Go to the Cloud SQL Instances page in the Google Cloud Console.
Go to the Cloud SQL Instances page
Create an instance.
On the Instance info page, select Show configuration options.
Open Backups, recovery, and high availability.
Select the High availability (regional) radio button.
Leave the Automate backups and Enable point-in-time recovery checkboxes enabled.

gcloud

Create the regional instance:

gcloud sql instances create [REGIONAL_INSTANCE_NAME] \
                     --availability-type=REGIONAL \
                     --database-version=[DATABASE_VERSION] \
                     --tier=[MACHINE_TYPE] \
                     --enable-bin-log

For a complete list of available parameters, see the gcloud sql instances create reference page.

Configure the root user:

gcloud sql users set-password root --host=% \
           --instance=[PRIMARY_INSTANCE_NAME]
           --password=[PASSWORD]

REST

For the complete list of parameters for this request, see the instances:insert page.

Create the regional instance.

Before using any of the request data below, make the following replacements:

project-id: The project ID
instance-name: The instance name
database-version: The database version enum string
region The GCP region
machine-type The machine type

HTTP method and URL:

POST https://www.googleapis.com/sql/v1beta4/projects/project-id/instances

Request JSON body:

{
  "name": "instance-name",
  "region": "region",
  "databaseVersion": "database-version",
   "settings": {
     "tier": "machine-type",
     "backupConfiguration": {
         "binaryLogEnabled": true,
         "enabled": true
      },
      "availabilityType": "REGIONAL"
   }
}

To send your request, expand one of these options:

curl (Linux, macOS, or Cloud Shell)

Note: The command below assumes that you have used either gcloud init or gcloud auth login to authenticate gcloud with your user account. You can check the currently active account by executing gcloud auth list.

Save the request body in a file called request.json, and execute the following command:

curl -X POST \
-H "Authorization: Bearer "$(gcloud auth print-access-token) \
-H "Content-Type: application/json; charset=utf-8" \
-d @request.json \
https://www.googleapis.com/sql/v1beta4/projects/project-id/instances

PowerShell (Windows)

Save the request body in a file called request.json, and execute the following command:

$cred = gcloud auth print-access-token
$headers = @{ "Authorization" = "Bearer $cred" }

Invoke-WebRequest `
  -Method POST `
  -Headers $headers `
  -ContentType: "application/json; charset=utf-8" `
  -InFile request.json `
  -Uri "https://www.googleapis.com/sql/v1beta4/projects/project-id/instances" | Select-Object -Expand Content

You should receive a JSON response similar to the following:

Response

{
  "kind": "sql#operation",
  "targetLink": "https://www.googleapis.com/sql/v1beta4/projects/project-id/instances/instance-name",
  "status": "PENDING",
  "user": "user@example.com",
  "insertTime": "2020-01-21T22:43:37.981Z",
  "operationType": "CREATE",
  "name": "operation-id",
  "targetId": "instance-name",
  "selfLink": "https://www.googleapis.com/sql/v1beta4/projects/project-id/operations/operation-id",
  "targetProject": "project-id"
}

When the instance finishes initializing, update the root password on the instance:
Before using any of the request data below, make the following replacements:
- project-id: The project ID
- instance-id: The instance ID
- password: The new root user password
HTTP method and URL:
```
PATCH https://www.googleapis.com/sql/v1beta4/projects/project-id/instances/instance-id/users?host=%25&name=root'
```
Request JSON body:
```
{
   "name": "root",
   "host": "%",
   "password": "password"}
```
To send your request, expand one of these options:
curl (Linux, macOS, or Cloud Shell)

Note: The command below assumes that you have used either gcloud init or gcloud auth login to authenticate gcloud with your user account. You can check the currently active account by executing gcloud auth list.

Save the request body in a file called request.json, and execute the following command:
```
curl -X PATCH \
-H "Authorization: Bearer "$(gcloud auth print-access-token) \
-H "Content-Type: application/json; charset=utf-8" \
-d @request.json \
https://www.googleapis.com/sql/v1beta4/projects/project-id/instances/instance-id/users?host=%25&name=root'
```
PowerShell (Windows)

Note: The command below assumes that you have used either gcloud init or gcloud auth login to authenticate gcloud with your user account. You can check the currently active account by executing gcloud auth list.

Save the request body in a file called request.json, and execute the following command:
```
$cred = gcloud auth print-access-token
$headers = @{ "Authorization" = "Bearer $cred" }

Invoke-WebRequest `
  -Method PATCH `
  -Headers $headers `
  -ContentType: "application/json; charset=utf-8" `
  -InFile request.json `
  -Uri "https://www.googleapis.com/sql/v1beta4/projects/project-id/instances/instance-id/users?host=%25&name=root'" | Select-Object -Expand Content
```
You should receive a successful status code (2xx) and an empty response.

For more details about creating an instance, see Creating Instances.

Configuring an existing instance for high availability

Configuring an existing instance for high availability causes a few minutes of downtime while the instance is reconfigured.

To configure an existing instance for high availability:

Console

Go to the Cloud SQL Instances page in the Google Cloud Console.
Go to the Cloud SQL Instances page
Click the instance name to open its Overview page.
Click Edit.
Open Backups, recovery, and high availability.
Enable the Automate backups and Enable point-in-time recovery checkboxes.
Select High availability (regional).
Click Save.
You are returned to the instance page for the primary instance while the instance is updated.

gcloud

Update the instance to be regional:

gcloud sql instances patch [INSTANCE_NAME] --availability-type REGIONAL --enable-bin-log --backup-start-time=[HH:MM]

For reference information, see gcloud sql instances patch.

REST

Check the primary instance to see if automatic backups and binary logs are enabled. These are required for high availability instances.

Before using any of the request data below, make the following replacements:

project-id: The project ID
instance-id: The instance ID

HTTP method and URL:

GET https://www.googleapis.com/sql/v1beta4/projects/project-id/instances/instance-id

To send your request, expand one of these options:

curl (Linux, macOS, or Cloud Shell)

Execute the following command:

curl -X GET \
-H "Authorization: Bearer "$(gcloud auth print-access-token) \
https://www.googleapis.com/sql/v1beta4/projects/project-id/instances/instance-id

PowerShell (Windows)

Execute the following command:

$cred = gcloud auth print-access-token
$headers = @{ "Authorization" = "Bearer $cred" }

Invoke-WebRequest `
  -Method GET `
  -Headers $headers `
  -Uri "https://www.googleapis.com/sql/v1beta4/projects/project-id/instances/instance-id" | Select-Object -Expand Content

You should receive a JSON response similar to the following:

{
  "kind": "sql#instance",
  "state": "RUNNABLE",
  "databaseVersion": "MYSQL_5_7",
  "settings": {
    "authorizedGaeApplications": [],
    "tier": "db-f1-micro",
    "kind": "sql#settings",
    "pricingPlan": "PER_USE",
    "replicationType": "SYNCHRONOUS",
    "activationPolicy": "ALWAYS",
    "ipConfiguration": {
      "authorizedNetworks": [],
      "ipv4Enabled": true
    },
    "locationPreference": {
      "zone": "asia-east1-a",
      "kind": "sql#locationPreference"
    },
    "dataDiskType": "PD_SSD",
    "backupConfiguration": {
      "startTime": "08:00",
      "kind": "sql#backupConfiguration",
      "enabled": true,
      "binaryLogEnabled": true
    },
    "settingsVersion": "13",
    "storageAutoResizeLimit": "0",
    "storageAutoResize": true,
    "dataDiskSizeGb": "10"
  },
  "etag": "etag-id",
  "ipAddresses": [
    {
      "type": "PRIMARY",
      "ipAddress": "10.0.0.1"
    }
  ],
  "serverCaCert": {
    "kind": "sql#sslCert",
    "certSerialNumber": "0",
    "cert": "certificate-id",
    "commonName": "C=US,O=Google\\, Inc,CN=Google Cloud SQL Server CA,dnQualifier=dn-qualifier-id",
    "sha1Fingerprint": "sha-id",
    "instance": "instance-id",
    "createTime": "2019-06-28T22:46:35.052Z",
    "expirationTime": "2029-06-25T22:47:35.052Z"
  },
  "instanceType": "CLOUD_SQL_INSTANCE",
  "project": "project-id",
  "serviceAccountEmailAddress": "service-acct-id@gcp-sa-cloud-sql.iam.gserviceaccount.com",
  "backendType": "SECOND_GEN",
  "selfLink": "https://www.googleapis.com/sql/v1beta4/projects/project-id/instances/instance-id",
  "connectionName": "project-id:region:instance-id",
  "name": "instance-id",
  "region": "asia-east1",
  "gceZone": "asia-east1-a"
}

The output contains a section similar to the following:

  "backupConfiguration": {
    "kind": "sql#backupConfiguration",
    "startTime": "12:00",
    "enabled": true,
    "binaryLogEnabled": true
    }

If either enabled or binaryLogEnabled are false, use the instances:patch method to enable them both. To enable backups, set enabled to true and startTime to a value which is the start of the backup window. To enable binary logging, set binaryLogEnabled to true.

Before using any of the request data below, make the following replacements:

project-id: The project ID
instance-id: The instance ID
start-time The time in the format "HH:MM"

HTTP method and URL:

PATCH https://www.googleapis.com/sql/v1beta4/projects/project-id/instances/instance-id

Request JSON body:

{
  "settings":
  {
    "backupConfiguration":
    {
      "startTime": "start-time",
      "enabled": true,
      "binaryLogEnabled": true
    }
  }
}

To send your request, expand one of these options:

curl (Linux, macOS, or Cloud Shell)

Save the request body in a file called request.json, and execute the following command:

curl -X PATCH \
-H "Authorization: Bearer "$(gcloud auth print-access-token) \
-H "Content-Type: application/json; charset=utf-8" \
-d @request.json \
https://www.googleapis.com/sql/v1beta4/projects/project-id/instances/instance-id

PowerShell (Windows)

Save the request body in a file called request.json, and execute the following command:

$cred = gcloud auth print-access-token
$headers = @{ "Authorization" = "Bearer $cred" }

Invoke-WebRequest `
  -Method PATCH `
  -Headers $headers `
  -ContentType: "application/json; charset=utf-8" `
  -InFile request.json `
  -Uri "https://www.googleapis.com/sql/v1beta4/projects/project-id/instances/instance-id" | Select-Object -Expand Content

You should receive a JSON response similar to the following:

Response

{
  "kind": "sql#operation",
  "targetLink": "https://www.googleapis.com/sql/v1beta4/projects/project-id/instances/instance-id",
  "status": "PENDING",
  "user": "user@example.com",
  "insertTime": "2020-01-21T22:43:37.981Z",
  "operationType": "UPDATE",
  "name": "operation-id",
  "targetId": "instance-id",
  "selfLink": "https://www.googleapis.com/sql/v1beta4/projects/project-id/operations/operation-id",
  "targetProject": "project-id"
}

Update the instance to be a regional instance:

Before using any of the request data below, make the following replacements:
- project-id: The project ID
- instance-name: The instance name
HTTP method and URL:
```
PATCH https://www.googleapis.com/sql/v1beta4/projects/project-id/instances/instance-name
```
Request JSON body:
```
{
  "settings": {"availabilityType": "REGIONAL" }
}
```
To send your request, expand one of these options:
curl (Linux, macOS, or Cloud Shell)

Note: The command below assumes that you have used either gcloud init or gcloud auth login to authenticate gcloud with your user account. You can check the currently active account by executing gcloud auth list.

Save the request body in a file called request.json, and execute the following command:
```
curl -X PATCH \
-H "Authorization: Bearer "$(gcloud auth print-access-token) \
-H "Content-Type: application/json; charset=utf-8" \
-d @request.json \
https://www.googleapis.com/sql/v1beta4/projects/project-id/instances/instance-name
```
PowerShell (Windows)

Note: The command below assumes that you have used either gcloud init or gcloud auth login to authenticate gcloud with your user account. You can check the currently active account by executing gcloud auth list.

Save the request body in a file called request.json, and execute the following command:
```
$cred = gcloud auth print-access-token
$headers = @{ "Authorization" = "Bearer $cred" }

Invoke-WebRequest `
  -Method PATCH `
  -Headers $headers `
  -ContentType: "application/json; charset=utf-8" `
  -InFile request.json `
  -Uri "https://www.googleapis.com/sql/v1beta4/projects/project-id/instances/instance-name" | Select-Object -Expand Content
```
You should receive a successful status code (2xx) and an empty response.

Initiating failover

Testing failover is optional, but is recommended so that you can see how your application responds in the event of a failover.

To learn more about failovers, see the Failover overview.

Console

Go to the Cloud SQL Instances page in the Google Cloud Console.
Go to the Cloud SQL Instances page
Click the primary instance name to open its Instance details page.
Click Failover in the button bar.

gcloud

Initiate the failover:

gcloud sql instances failover [PRIMARY_INSTANCE_NAME]

REST

Describe the primary instance to get the value of the settingsVersion field.

Before using any of the request data below, make the following replacements:

project-id: The project ID
instance-id: The instance ID

HTTP method and URL:

GET https://www.googleapis.com/sql/v1beta4/projects/project-id/instances/instance-id

To send your request, expand one of these options:

curl (Linux, macOS, or Cloud Shell)

Execute the following command:

curl -X GET \
-H "Authorization: Bearer "$(gcloud auth print-access-token) \
https://www.googleapis.com/sql/v1beta4/projects/project-id/instances/instance-id

PowerShell (Windows)

Execute the following command:

$cred = gcloud auth print-access-token
$headers = @{ "Authorization" = "Bearer $cred" }

Invoke-WebRequest `
  -Method GET `
  -Headers $headers `
  -Uri "https://www.googleapis.com/sql/v1beta4/projects/project-id/instances/instance-id" | Select-Object -Expand Content

You should receive a JSON response similar to the following:

{
  "kind": "sql#instance",
  "state": "RUNNABLE",
  "databaseVersion": "MYSQL_5_7",
  "settings": {
    "authorizedGaeApplications": [],
    "tier": "db-f1-micro",
    "kind": "sql#settings",
    "pricingPlan": "PER_USE",
    "replicationType": "SYNCHRONOUS",
    "activationPolicy": "ALWAYS",
    "ipConfiguration": {
      "authorizedNetworks": [],
      "ipv4Enabled": true
    },
    "locationPreference": {
      "zone": "asia-east1-a",
      "kind": "sql#locationPreference"
    },
    "dataDiskType": "PD_SSD",
    "backupConfiguration": {
      "startTime": "08:00",
      "kind": "sql#backupConfiguration",
      "enabled": true,
      "binaryLogEnabled": true
    },
    "settingsVersion": "13",
    "storageAutoResizeLimit": "0",
    "storageAutoResize": true,
    "dataDiskSizeGb": "10"
  },
  "etag": "etag-id",
  "ipAddresses": [
    {
      "type": "PRIMARY",
      "ipAddress": "10.0.0.1"
    }
  ],
  "serverCaCert": {
    "kind": "sql#sslCert",
    "certSerialNumber": "0",
    "cert": "certificate-id",
    "commonName": "C=US,O=Google\\, Inc,CN=Google Cloud SQL Server CA,dnQualifier=dn-qualifier-id",
    "sha1Fingerprint": "sha-id",
    "instance": "instance-id",
    "createTime": "2019-06-28T22:46:35.052Z",
    "expirationTime": "2029-06-25T22:47:35.052Z"
  },
  "instanceType": "CLOUD_SQL_INSTANCE",
  "project": "project-id",
  "serviceAccountEmailAddress": "service-acct-id@gcp-sa-cloud-sql.iam.gserviceaccount.com",
  "backendType": "SECOND_GEN",
  "selfLink": "https://www.googleapis.com/sql/v1beta4/projects/project-id/instances/instance-id",
  "connectionName": "project-id:region:instance-id",
  "name": "instance-id",
  "region": "asia-east1",
  "gceZone": "asia-east1-a"
}

Initiate the failover:

Before using any of the request data below, make the following replacements:

project-id: The project ID
instance-name: The instance name
settings-version: The settingsVersion from instanceInfo

HTTP method and URL:

POST https://www.googleapis.com/sql/v1beta4/projects/project-id/instances/instance-name/failover

Request JSON body:

{
  "failoverContext":
     {
        "settingsVersion":"settings-version"
     }
}

To send your request, expand one of these options:

curl (Linux, macOS, or Cloud Shell)

Save the request body in a file called request.json, and execute the following command:

curl -X POST \
-H "Authorization: Bearer "$(gcloud auth print-access-token) \
-H "Content-Type: application/json; charset=utf-8" \
-d @request.json \
https://www.googleapis.com/sql/v1beta4/projects/project-id/instances/instance-name/failover

PowerShell (Windows)

Save the request body in a file called request.json, and execute the following command:

$cred = gcloud auth print-access-token
$headers = @{ "Authorization" = "Bearer $cred" }

Invoke-WebRequest `
  -Method POST `
  -Headers $headers `
  -ContentType: "application/json; charset=utf-8" `
  -InFile request.json `
  -Uri "https://www.googleapis.com/sql/v1beta4/projects/project-id/instances/instance-name/failover" | Select-Object -Expand Content

You should receive a JSON response similar to the following:

Response

{
  "kind": "sql#operation",
  "targetLink": "https://www.googleapis.com/sql/v1beta4/projects/project-id/instances/instance-name",
  "status": "PENDING",
  "user": "user@example.com",
  "insertTime": "2020-01-21T22:43:37.981Z",
  "operationType": "CREATE",
  "name": "operation-id",
  "targetId": "instance-name",
  "selfLink": "https://www.googleapis.com/sql/v1beta4/projects/project-id/operations/operation-id",
  "targetProject": "project-id"
}

The instance fails over and is not available to serve data for a few minutes.

Verifying an instance has high availability

To verify an instance has high availability:

Console

Go to the Cloud SQL Instances page in the Google Cloud Console.
Go to the Cloud SQL Instances page
Click an instance name to open its Instance details page.
Under Configuration, it shows Highly available (regional).

gcloud

gcloud sql instances describe [INSTANCE_NAME]

The output indicates availabilityType is REGIONAL.

REST

Before using any of the request data below, make the following replacements:

project-id: The project ID
instance-id: The instance ID

HTTP method and URL:

GET https://www.googleapis.com/sql/v1beta4/projects/project-id/instances/instance-id

To send your request, expand one of these options:

curl (Linux, macOS, or Cloud Shell)

Execute the following command:

curl -X GET \
-H "Authorization: Bearer "$(gcloud auth print-access-token) \
https://www.googleapis.com/sql/v1beta4/projects/project-id/instances/instance-id

PowerShell (Windows)

Execute the following command:

$cred = gcloud auth print-access-token
$headers = @{ "Authorization" = "Bearer $cred" }

Invoke-WebRequest `
  -Method GET `
  -Headers $headers `
  -Uri "https://www.googleapis.com/sql/v1beta4/projects/project-id/instances/instance-id" | Select-Object -Expand Content

You should receive a JSON response similar to the following:

{
  "kind": "sql#instance",
  "state": "RUNNABLE",
  "databaseVersion": "MYSQL_5_7",
  "settings": {
    "authorizedGaeApplications": [],
    "tier": "db-f1-micro",
    "kind": "sql#settings",
    "pricingPlan": "PER_USE",
    "replicationType": "SYNCHRONOUS",
    "activationPolicy": "ALWAYS",
    "ipConfiguration": {
      "authorizedNetworks": [],
      "ipv4Enabled": true
    },
    "locationPreference": {
      "zone": "asia-east1-a",
      "kind": "sql#locationPreference"
    },
    "dataDiskType": "PD_SSD",
    "backupConfiguration": {
      "startTime": "08:00",
      "kind": "sql#backupConfiguration",
      "enabled": true,
      "binaryLogEnabled": true
    },
    "settingsVersion": "13",
    "storageAutoResizeLimit": "0",
    "storageAutoResize": true,
    "dataDiskSizeGb": "10"
  },
  "etag": "etag-id",
  "ipAddresses": [
    {
      "type": "PRIMARY",
      "ipAddress": "10.0.0.1"
    }
  ],
  "serverCaCert": {
    "kind": "sql#sslCert",
    "certSerialNumber": "0",
    "cert": "certificate-id",
    "commonName": "C=US,O=Google\\, Inc,CN=Google Cloud SQL Server CA,dnQualifier=dn-qualifier-id",
    "sha1Fingerprint": "sha-id",
    "instance": "instance-id",
    "createTime": "2019-06-28T22:46:35.052Z",
    "expirationTime": "2029-06-25T22:47:35.052Z"
  },
  "instanceType": "CLOUD_SQL_INSTANCE",
  "project": "project-id",
  "serviceAccountEmailAddress": "service-acct-id@gcp-sa-cloud-sql.iam.gserviceaccount.com",
  "backendType": "SECOND_GEN",
  "selfLink": "https://www.googleapis.com/sql/v1beta4/projects/project-id/instances/instance-id",
  "connectionName": "project-id:region:instance-id",
  "name": "instance-id",
  "region": "asia-east1",
  "gceZone": "asia-east1-a"
}

The output indicates availabilityType is REGIONAL.

Disabling high availability on an instance

Before you perform this procedure, make sure there are no operations currently running on the instance.

To disable high availability:

Console

Go to the Cloud SQL Instances page in the Google Cloud Console.
Go to the Cloud SQL Instances page
Select the instance you want to disable high availability on.
On the Instance details page, click EDIT.
Open Auto backups.
Under Availability click Single zone.
Click Save. This edit requires a restart of the instance.
When you see the message box, click SAVE AND RESTART.

gcloud

For reference information, see gcloud sql instances patch.

gcloud sql instances patch [INSTANCE_NAME]
           --availability-type ZONAL

REST

The following request uses the instances:patch method to change the availability type on the instance to ZONAL.

Before using any of the request data below, make the following replacements:

project-id: The project ID
instance-name: The instance name

HTTP method and URL:

PATCH https://www.googleapis.com/sql/v1beta4/projects/project-id/instances/instance-name

Request JSON body:

{
  "settings": {"availabilityType": "ZONAL" }
}

To send your request, expand one of these options:

curl (Linux, macOS, or Cloud Shell)

Save the request body in a file called request.json, and execute the following command:

curl -X PATCH \
-H "Authorization: Bearer "$(gcloud auth print-access-token) \
-H "Content-Type: application/json; charset=utf-8" \
-d @request.json \
https://www.googleapis.com/sql/v1beta4/projects/project-id/instances/instance-name

PowerShell (Windows)

Save the request body in a file called request.json, and execute the following command:

$cred = gcloud auth print-access-token
$headers = @{ "Authorization" = "Bearer $cred" }

Invoke-WebRequest `
  -Method PATCH `
  -Headers $headers `
  -ContentType: "application/json; charset=utf-8" `
  -InFile request.json `
  -Uri "https://www.googleapis.com/sql/v1beta4/projects/project-id/instances/instance-name" | Select-Object -Expand Content

You should receive a successful status code (2xx) and an empty response.

Updating an instance from legacy to current high availability

To update your instance from the legacy to the new high-availability configuration, do the following:

Delete the failover replica on the MySQL instances you want to update. See Legacy configuration: Disabling high availability on an instance.
Configure the instance to use the current version of high availability. See Configuring an existing instance for high availability.

Troubleshooting

Click the links in the table for details:

For this problem...	The issue might be...	Try this...
Can't find metrics for manual failover.	Only automatic failovers go into the metrics.	N/A
CPU and RAM are near 100% usage	Instance machine size is too small for the load.	Upgrade the instance machine size.

Can't find metrics for manual failover

You performed a manual failover and can't find a corresponding entry in Metrics Explorer in the automatic failover metrics.

The issue might be

Only automatic failovers go into the metrics. Manually initiated failovers do not.

Things to try

N/A

CPU and RAM are near 100% usage

Cloud SQL instance resources (CPU and RAM) are near 100% usage, causing the high availability instance to go down.

The issue might be

The instance machine size is too small for the load.

Things to try

Edit the instance to upgrade to a larger machine size to get more CPUs and memory.

What's next

Learn more about how the high availability configuration works.
Test how your application responds to lost connections by restarting your instance.
Learn more about managing your database connections.
Learn more about Google Cloud's operations suite.
Learn more about the Legacy configuration for high availability.
Create read replicas for your instance.