Failover and Recovery Scenarios in InnoDB Cluster and ClusterSet

In managing MySQL databases, particularly in high-availability environments like InnoDB Cluster and ClusterSet, it's crucial to have robust failover and recovery mechanisms in place. These systems offer advanced features for maintaining data integrity and availability, but they require careful configuration and management. The following content delves into the specifics of configuring and scripting for optimal failover and recovery in both InnoDB Cluster and ClusterSet environments. It provides practical configuration recommendations and example scripts, aimed at enhancing the reliability and efficiency of these MySQL setups. Whether you're dealing with automatic failover scenarios, manual intervention, or node recovery processes, these insights will help ensure your MySQL databases remain resilient and consistently available.

InnoDB Cluster Failover and Recovery

1. Automatic Failover Configuration

• Group Replication Setup: Ensure group_replication plugin is installed and enabled.
  INSTALL PLUGIN group_replication SONAME 'group_replication.so';

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  INSTALL PLUGIN group_replication SONAME 'group_replication.so';

• Configuring Members: Set unique server_id for each member and configure replication settings.
  SET GLOBAL server_id = 1; -- Different for each member SET GLOBAL group_replication_group_name = 'uuid()'; SET GLOBAL group_replication_start_on_boot = ON;

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  SET GLOBAL server_id = 1;  -- Different for each member SET GLOBAL group_replication_group_name = 'uuid()'; SET GLOBAL group_replication_start_on_boot = ON;

2. Manual Failover Process

• Force Primary Election: When necessary, you can manually force a member to become the primary.
  SET GLOBAL group_replication_force_members = 'member_uuid';

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  SET GLOBAL group_replication_force_members = 'member_uuid';

3. Node Recovery Script

• Rejoining the Cluster: Use a script to automate the process of rejoining a node to the cluster.
  #!/bin/bash # Script to rejoin a node to the cluster mysql -e "STOP GROUP_REPLICATION; START GROUP_REPLICATION;";

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  #!/bin/bash # Script to rejoin a node to the cluster mysql -e "STOP GROUP_REPLICATION; START GROUP_REPLICATION;";

InnoDB ClusterSet Failover and Recovery

1. ClusterSet Configuration

• Primary and Replica Clusters: Configure one cluster as primary and others as replicas.
  -- On the primary CREATE CLUSTERSET primary_cluster; -- On replicas CLUSTERSET REPLICATE FROM primary_cluster AT primary_host:port;

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  -- On the primary CREATE CLUSTERSET primary_cluster; -- On replicas CLUSTERSET REPLICATE FROM primary_cluster AT primary_host:port;

2. Failover to a Replica Cluster

• Switchover Script: Use a script to switch primary roles between clusters.
  #!/bin/bash # Switchover to a new primary cluster mysql -e "CLUSTERSET SWITCHOVER TO replica_cluster;";

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  #!/bin/bash # Switchover to a new primary cluster mysql -e "CLUSTERSET SWITCHOVER TO replica_cluster;";

3. Recovery and Synchronization

• Resynchronization Script: After failover, automate the resynchronization process.
  #!/bin/bash # Resynchronize a cluster after recovery mysql -e "CLUSTERSET REPLICATE FROM new_primary_cluster AT host:port;";

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  #!/bin/bash # Resynchronize a cluster after recovery mysql -e "CLUSTERSET REPLICATE FROM new_primary_cluster AT host:port;";

General Configuration Recommendations

• Quorum Configuration: Carefully configure the quorum settings to avoid split-brain scenarios.
  SET GLOBAL group_replication_consistency = 'BEFORE_ON_PRIMARY_FAILOVER';

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  SET GLOBAL group_replication_consistency = 'BEFORE_ON_PRIMARY_FAILOVER';

• Performance Monitoring: Implement scripts to continuously monitor cluster health.
  #!/bin/bash # Monitor cluster health mysql -e "SELECT MEMBER_STATE FROM performance_schema.replication_group_members;";

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  #!/bin/bash # Monitor cluster health mysql -e "SELECT MEMBER_STATE FROM performance_schema.replication_group_members;";

• Regular Backups: Automate backups for disaster recovery.
  #!/bin/bash # Backup script mysqldump -u root -p --all-databases > all_databases.sql

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  #!/bin/bash # Backup script   mysqldump -u root -p --all-databases > all_databases.sql

Conclusion

Implementing failover and recovery in InnoDB Cluster and ClusterSet requires careful planning and configuration. Utilizing scripts can help automate many aspects of this process, enhancing the reliability and efficiency of failover operations. Regular testing and validation of these scripts and configurations are critical to ensure the high availability and durability of your MySQL deployment.