Scaling Down Your MySQL Cluster

This topic describes how to safely scale down your MySQL cluster to a single node.

By default, MySQL is a single node. To take advantage of the high availability features of MySQL, you may have scaled the configuration up to three nodes.

Note: If you are running the MySQL cluster with only a single node, you do not need to perform these steps.

Check the Health of Your Cluster

Before scaling down your MySQL cluster, perform the following actions to ensure the cluster is healthy.

  1. Use the Cloud Foundry Command Line Interface (cf CLI) to target the API endpoint of your Pivotal Cloud Foundry (PCF) deployment:

    $ cf api api.YOUR-SYSTEM-DOMAIN
    Setting api endpoint to api.YOUR-SYSTEM-DOMAIN...

    API endpoint: https://api.YOUR-SYSTEM-DOMAIN... (API version: 2.54.0) Not logged in. Use 'cf login' to log in.

  2. Log in with your User Account and Authentication (UAA) Administrator user credentials. Obtain these credentials by clicking the Credentials tab of the Elastic Runtime tile, locating the Admin Credentials entry in the UAA section, and clicking Link to Credential.

    $ cf login -u admin
    API endpoint: https://api.YOUR-SYSTEM-DOMAIN

    Password> Authenticating... OK

  3. Create a test organization to verify the database across all nodes:

    $ cf create-org data-integrity-test-organization
    Creating org data-integrity-test-organization as admin...

    Assigning role OrgManager to user admin in org data-integrity-test-organization ... OK

    TIP: Use 'cf target -o data-integrity-test-organization' to target new org

  4. Obtain the IP addresses of your MySQL server by performing the following steps:

    1. From the PCF Installation Dashboard, click the Pivotal Elastic Runtime tile.
    2. Click the Status tab.
    3. Record the IP addresses for all instances of the MySQL Server job.
  5. Retrieve Cloud Controller database credentials from CredHub using the Ops Manager API:

    1. Perform the procedures in the Using the Ops Manager API topic to authenticate and access the Ops Manager API.
    2. Use the GET /api/v0/deployed/products endpoint to retrieve a list of deployed products, replacing UAA-ACCESS-TOKEN with the access token recorded in the previous step:
      $ curl "https://OPS-MAN-FQDN/api/v0/deployed/products" \
      -X GET \
      -H "Authorization: Bearer UAA-ACCESS-TOKEN"
    3. In the response to the above request, locate the product with an installation_name starting with cf- and copy its guid.
    4. Run the following curl command, replacing PRODUCT-GUID with the value of guid from the previous step:
      $ curl "https://OPS-MAN-FQDN/api/v0/deployed/products/PRODUCT-GUID/variables?name=cc-db-credentials" \
      -X GET \
      -H "Authorization: Bearer UAA-ACCESS-TOKEN"
    5. Record the Cloud Controller database username and password from the response to the above request.
  6. SSH into the Ops Manager VM. Because the procedures vary by IaaS, review the SSH into Ops Manager section of the Advanced Troubleshooting with the BOSH CLI topic for specific instructions.

  7. For each of the MySQL server IP addresses recorded above, perform the following steps from the Ops Manager VM:

    1. Query the new organization with the following command, replacing YOUR-IP with the IP address of the MySQL server and YOUR-IDENTITY with the identity value of the CCDB credentials obtained above:
      $ mysql -h YOUR-IP -u YOUR-IDENTITY -D ccdb -p -e "select created_at, name from organizations where name = 'data-integrity-test-organization'"
    2. When prompted, provide the password value of the CCDB credentials obtained above.
    3. Examine the output of the mysql command and verify the created_at date is recent.
      | created_at          | name                             |
      | 2016-05-28 01:11:42 | data-integrity-test-organization |
  8. If each MySQL server instance does not return the same created_at result, contact Pivotal Support before proceeding further or making any changes to your deployment. If each MySQL server instance does return the same result, then you can safely proceed to scaling down your cluster to a single node by performing the steps in the following section.

Scale Down Your Cluster

  1. From the PCF Installation Dashboard, click the Pivotal Elastic Runtime tile.
  2. Select Resource Config.
  3. Use the drop-down menu to change the Instances count for MySQL Server to 1.
  4. Click Save to apply the changes.
  5. Delete your test organization with the following cf CLI command:
    $ cf delete-org data-integrity-test-organization
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