Overview of MySQL Replication

This section provides an overview of the MySQL replication resource groups. A protection group that secures MySQL databases with MySQL replication consists of the following two resource groups securing a third resource group that is not part of the protection group on each cluster:

• MySQL Database Resource Group

• MySQL Replication Resource Group

• MySQL Application Resource Group

The MySQL database resource group holding a MySQL database is the foundation underneath the protection group. So, there must be strong positive dependencies with failover delegation should exist from the two resource groups in the protection group and the database resource group.

MySQL Database Resource Group

The MySQL database resource group typically contains the following resources:

• HAStoragePlus resource, which manages database storage

• Logical host resource, which provides the address to connect with the MySQL replication user

• MySQL database resource, which resides on top of the first two resources to make the database highly available locally

On single-node clusters, the HAStoragePlus resource can be omitted. The creation of the database resource group and its resources is the topic of Oracle Solaris Cluster Data Service for MySQL Guide.

The database resource group and its objects can have different names across the clusters.

MySQL Replication Resource Group

The MySQL replication resource group contains the MySQL replication resource. This resource does not start or stop any process. Its only purpose is to monitor the status of the MySQL database replication.

MySQL Application Resource Group

The MySQL application resource group must contain at least a logical host resource, which provides the address for all the clients to use for connections to the database.

The MySQL application resource group also contains any application that depends on the MySQL database in the cluster. For example, if an HA for Apache Tomcat application server is configured in the cluster, its failover resource is added to the MySQL application resource group, assuming that the servlet that is deployed in Apache Tomcat uses for database access the logical host that is in the MySQL application resource group. This resource group is added to the protection group, which then ensures that clients connect only to the master database and not to the slave database. Connection of the application resource group to the slave database instead of the master database might compromise data consistency.