Maintenance in Managed Service for MySQL
In Managed Service for MySQL, maintenance means:
- Automatic installation of MySQL updates and revisions for hosts (including disabled clusters).
- Changes to the host class and storage size.
- Other maintenance activities.
Maintenance window
You can set the preferred maintenance time when creating a cluster or updating its settings:
- arbitrary (default): Maintenance can be performed at any time.
- by schedule: Set the preferred maintenance start time, i.e., the day and time (UTC) you want to perform maintenance at. For example, you can choose a time window when the cluster is least loaded.
Maintenance procedure
In Managed Service for MySQL single-host clusters, a master host undergoes maintenance. Therefore, it may become unavailable in case it is restarted.
In multi-host clusters, the maintenance is run as follows:
- Replicas undergo maintenance one by one. The replicas are queued randomly. A replica becomes unavailable while it is being restarted during maintenance.
- Master host undergoes maintenance and gets updated. If it is restarted and becomes unavailable, one of the replicas takes its role. If you access a cluster using the FQDN of the master host, the cluster may become unavailable. To make your application continuously available, access the cluster using a special FQDN that always points to the master host.