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Migrating databases from Yandex Managed Service for MySQL® to a third-party MySQL® cluster

Written by
Updated at July 8, 2024

Note

Data migration from a third-party MySQL® cluster is described in Migrating data from a third-party MySQL® cluster.

To migrate a database deployed in a Managed Service for MySQL® cluster to a third-party MySQL® cluster:

  1. Transfer data.
  2. Disable data writes to the source database.
  3. Transfer the load to a third-party cluster.

Migration across versions is supported. For example, you can move databases from MySQL® 5.7 to 8. The MySQL® major version on a third-party cluster must be the same or higher than the version in the Managed Service for MySQL® cluster.

There are two ways to migrate data from a Managed Service for MySQL® source cluster to a third-party MySQL® target cluster:

Getting started

Prepare the target cluster:

  • Create a MySQL® database in any suitable configuration.
  • Make sure that you can connect to the target cluster hosts from the internet.

Additionally, to migrate data using external MySQL® replication:

  • Make sure all the source cluster's hosts are accessible by a public IP address so that the target cluster can connect to the source. To do this:
  • Install Managed Service for MySQL® server SSL certificates on the target cluster's hosts. They are required to connect to the publicly available source cluster.
  • If you need to, set up a firewall and security groups so you can connect to the source cluster from the target cluster, as well as to each cluster separately, e.g., using the mysql utility.
  • Make sure you can connect to the source cluster's hosts from the target cluster's hosts.
  • Make sure that you can connect to the source cluster and the target cluster via SSL.

Transferring data using Yandex Data Transfer

  1. Prepare the source cluster database.

  2. Prepare the target cluster database.

  3. Set up the endpoints and transfer:

    1. Create a source endpoint:

      • Database type: MySQL

      • Connection settings: Managed Service for MySQL cluster

        Specify the source cluster ID.

    2. Create a target endpoint:

      • Database type: MySQL

      • Connection settings: Custom installation

        Specify the target cluster connection settings.

    3. Create a transfer of the Snapshot and increment type that will use the created endpoints.

    4. Activate the transfer.

    1. If you do not have Terraform yet, install it.

    2. Get the authentication credentials. You can add them to environment variables or specify them later in the provider configuration file.

    3. Configure and initialize a provider. There is no need to create a provider configuration file manually, you can download it.

    4. Place the configuration file in a separate working directory and specify the parameter values. If you did not add the authentication credentials to environment variables, specify them in the configuration file.

    5. Download the transfer and the data-transfer-mmy-mysql.tf endpoint configuration file to the same working directory.

    6. Specify the following in the configuration file:

    7. Make sure the Terraform configuration files are correct using this command:

      terraform validate

      If there are any errors in the configuration files, Terraform will point them out.

    8. Create the required infrastructure:

      1. Run the command to view planned changes:

        terraform plan

        If the resource configuration descriptions are correct, the terminal will display a list of the resources to modify and their parameters. This is a test step. No resources are updated.

      2. If you are happy with the planned changes, apply them:

        1. Run the command:

          terraform apply

        2. Confirm the update of resources.

        3. Wait for the operation to complete.

      All the required resources will be created in the specified folder. You can check resource availability and their settings in the management console.

      Once created, your transfer will be activated automatically.

    Warning

    Avoid any changes to the data schema in the source and target clusters during the transfer operation. For more information, see Working with databases during transfer.

  4. Wait for the transfer status to change to Replicating.

  5. Switch the source cluster to "read-only" mode and transfer the load to the target cluster.

  6. On the transfer monitoring page, wait for the Maximum data transfer delay metric to decrease to zero. This means that all changes that occurred in the source cluster after data was copied are transferred to the target cluster.

  7. Deactivate the transfer and wait for its status to change to Stopped.

    For more information about transfer statuses, see Transfer lifecycle.

  8. Delete the endpoints and the transfer you created:

    If you created your endpoints and transfer manually:

    1. Delete the stopped transfer.
    2. Delete the source and target endpoints.

    If you used Terraform to create your endpoints and transfer:

    1. In the command line, go to the folder that houses the current Terraform configuration file with an infrastructure plan.

    2. Delete the data-transfer-mmy-mysql.tf configuration file.

    3. Make sure the Terraform configuration files are correct using this command:

      terraform validate

      If there are any errors in the configuration files, Terraform will point them out.

    4. Confirm updating the resources.

      1. Run the command to view planned changes:

        terraform plan

        If the resource configuration descriptions are correct, the terminal will display a list of the resources to modify and their parameters. This is a test step. No resources are updated.

      2. If you are happy with the planned changes, apply them:

        1. Run the command:

          terraform apply

        2. Confirm the update of resources.

        3. Wait for the operation to complete.

      All the resources described in the data-transfer-mmy-mysql.tf configuration file will be deleted.

Transferring data using external replication

  1. Transfer a logical dump of the database.
  2. Configure the user in the source cluster to manage replication.
  3. Start replication in the target cluster.
  4. Monitor the migration process until it is complete.
  5. Complete your migration.

Transfer a logical dump of the database

A logical dump is a file with a set of commands running which one by one you can restore the state of a database. It is created using the mysqldump utility. To ensure that a logical dump is complete, pause data writes to the database before creating it.

  1. Request the current position of the binary log to make sure that restoring the logical dump is consistent:

    SHOW MASTER STATUS;

    +-------------------------+----------+--------------+------------------+-----------------------------+
| File                    | Position | Binlog_Do_DB | Binlog_Ignore_DB | Executed_Gtid_Set           |
+-------------------------+----------+--------------+------------------+-----------------------------+
| mysql-bin-log-...000224 |  2058567 |              |                  | d827098b-...00b86:1-1575866 |
+-------------------------+----------+--------------+------------------+-----------------------------+
1 row in set (0.00 sec)

    Write down the File and Position values. You will need them when starting replication.

  2. Create a dump of the source cluster database:

    mysqldump \
    --databases=<DB_name> \
    --routines \
    --host=<master_host_FQDN> \
    --ssl-ca=<SSL_certificate_path> \
    --user=<DB_owner_username> > <dump_file>

    Tip

    Use a special FQDN that always points to the current master host of Managed Service for MySQL® clusters.

  3. Restore the database from the dump on the target cluster:

    mysql --host=<master_host_FQDN> \
      --user=<username> \
      --password \
      --port=3306 \
      --ssl-ca=<SSL_certificate_path> \
      --ssl-mode=VERIFY_IDENTITY \
      --line-numbers \
      <DB_name> < <dump_file>

    mysql --host=<master_host_FQDN> \
      --user=<username> \
      --password \
      --port=3306 \
      --line-numbers \
      <DB_name> < <dump_file>

  4. Create a user with full access rights to the database being migrated in the target cluster:

    CREATE USER '<username>'@'%' IDENTIFIED BY '<password>';
GRANT ALL PRIVILEGES ON <DB_name>.* TO '<username>'@'%';

Configure the user in the source cluster to manage replication

MySQL® uses the master-replica model when performing replication: the target cluster replicates the changes of the source cluster's binary log to its relay log. The host replica reproduces the changes from the relay log applying them to its own data.

To get binary log changes and manage the replication flow in the source cluster:

  1. Create a user.
  2. Assign the ALL_PRIVILEGES role to this user for the source cluster database.
  3. Assign the REPLICATION CLIENT and REPLICATION SLAVE global privileges to this user.

The target cluster will connect to the source cluster on behalf of this user.

Start replication in the target cluster

  1. Change the target cluster's /etc/mysql/my.cnf configuration file to start replication:

    [mysqld]
...
log_bin = mysql-bin
server_id = 2
relay-log = /var/lib/mysql/mysql-relay-bin
relay-log-index = /var/lib/mysql/mysql-relay-bin.index

gtid-mode = on
enforce-gtid-consistency = on

    Where:

    • log_bin: The name of the binary log in the target cluster.
    • server_id: The target cluster ID. The default value is 1. However, to run replication, make sure that the values of the source and target cluster IDs are different.
    • relay-log: The path to the relay log.
    • relay-log-index: The path to the relay log index.

    Enable the gtid-mode and enforce-gtid-consistency options to prepare for replication. In Managed Service for MySQL® clusters, they are always activated.

  2. Restart the mysql service:

    sudo systemctl restart mysql

  3. Connect to the target cluster on behalf of the user that is granted full access rights to the database being migrated.

  4. Enable replication for this database and disable replication for service databases (they are replicated by default):

    CHANGE REPLICATION FILTER
    REPLICATE_DO_DB=(
        <target_cluster_DB_name>
    ),
    REPLICATE_IGNORE_DB=(
        sys,
        mysql,
        performance_schema,
        information_schema
    );

  5. To assign a master for the target cluster, specify the parameters of the source cluster's master host:

    Tip

    Use a special FQDN that always points to the current master host of Managed Service for MySQL® clusters.

    CHANGE MASTER TO
      MASTER_HOST = '<master_host_FQDN>',
      MASTER_USER = '<name_of_the_user_to_manage_replication>',
      MASTER_PASSWORD = '<user_password>',
      MASTER_LOG_FILE = '<File_value_from_the_binary_log_position_request>',
      MASTER_LOG_POS = <Position_value_from_the_binary_log_position_request>,
      MASTER_SSL_CA = '<SSL_certificate_path>',
      MASTER_SSL_VERIFY_SERVER_CERT = 0,
      MASTER_SSL = 1;

  6. Start the relay log's replication:

    START SLAVE;

This starts the process of migrating data from the source cluster's database to the target cluster's database.

Track the migration process

Use the command that returns the replication status:

SHOW SLAVE STATUS\G

*************************** 1. row ***************************
           Slave_IO_State: Waiting for master to send event
              Master_Host: rc1a-hxk9audl********.mdb.yandexcloud.net
              Master_User: replica-my
              Master_Port: 3306
            Connect_Retry: 60
          Master_Log_File: mysql-bin-log-rc1a-hxk9audl********-mdb-yandexcloud-net.000225
      Read_Master_Log_Pos: 1702815
           Relay_Log_File: 6b6d647a39b6-relay-bin.000084
            Relay_Log_Pos: 409
            ...

Field values show the replication status:

  • Slave_IO_State and Slave_SQL_Running_State: I/O state of the binary log and relay log streams. If replication is successful, both streams are active.
  • Read_Master_Log_Pos: The last position read from the master host log.
  • Seconds_Behind_Master: Replica's lag behind the master (seconds).
  • Last_IO_Error and Last_SQL_Error: Replication errors.

For more information about replication status, see the MySQL® documentation.

Complete your migration

  1. Remove the load from the source cluster and make sure that the application does not write data to the source cluster database. To do this, change the custom source cluster setting MAX_UPDATES_PER_HOUR to 1.

  2. Wait for the Seconds_Behind_Master metric value to decrease to zero. This means that all changes that occurred in the source cluster after creating the logical dump are transferred to the target cluster.

  3. Stop replication in the target cluster:

    STOP SLAVE;

  4. Transfer the load to the target cluster.

  5. Remove the user managing replication on the source cluster.

  6. Remove the user with full access rights to the migrated database on the target cluster if you no longer need this user.

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