Maintenance in Managed Service for Redis

Maintenance means:

• Automatic installation of DBMS updates and revisions for hosts (including disabled clusters).
• Changes to the host class and storage size.
• Other maintenance activities.

Changing a major DBMS version is not part of maintenance. For more information about major version changes, see Redis version upgrade.

Maintenance windowMaintenance window

You can set the preferred maintenance time when creating a cluster or updating its settings:

• The arbitrary option (default) allows performing maintenance at any time.
• The by schedule option allows setting the preferred maintenance start day and time (UTC). For example, you can choose a time when the cluster is least loaded.

Maintenance procedureMaintenance procedure

The way of running the Managed Service for Redis cluster maintenance depends on the number of hosts and whether there are any shards.

Non-sharded clustersNon-sharded clusters

Maintenance is performed as follows:

1. Replica hosts undergo maintenance one by one. The hosts are queued randomly. A replica becomes temporarily unavailable if it needs to be restarted during maintenance.
2. Maintenance is performed on a master host. If it is restarted and becomes unavailable, one of the replicas takes its role. A single-host cluster will be unavailable during its maintenance.

Sharded clusterSharded cluster

In sharded clusters, maintenance is performed shard by shard in ascending order by shard number. Host maintenance in each shard is the same as in non-sharded clusters:

1. Replica hosts undergo maintenance one by one. The hosts are queued randomly. A replica becomes temporarily unavailable if it needs to be restarted during maintenance.
2. Maintenance is performed on a master host. If it is restarted and becomes unavailable, one of the replicas takes its role. A single-host shard will be unavailable during its maintenance.