7.13.2. Performing Maintenance on a Primary

Maintenance, including MySQL admin or schema updates, should not be performed directly on a Primary as this may upset the replication and therefore availability and functionality of the Replicas which are reading from the Primary.

To effectively make the modifications, you should switch the Primary host, then operate on the Primary as if it were Replica, removing it from the replicator service configuration. This helps to minimize any problems or availability that might be cause by performing operations directly on the Primary.

The complete sequence and commands required to perform maintenance on an active Primary are shown in the table below. The table assumes a dataservice with three datasources:

Step Description Command host1 host2 host3
1 Initial state   Primary Replica Replica
2 Switch Primary to host2 See Section 7.11, “Switching Primary Hosts” Replica Primary Replica
3 Put Replica into OFFLINE state trepctl -host host1 offline Offline Primary Replica
4 Perform maintenance   Offline Primary Replica
5 Validate the host1 server configuration tpm validate Offline Primary Replica
6 Put the Replica online trepctl -host host1 online Replica Primary Replica
7 Ensure the Replica has caught up trepctl -host host1 status Replica Primary Replica
8 Switch Primary back to host1 See Section 7.11, “Switching Primary Hosts” Primary Replica Replica