Maintenance in Yandex Managed Service for Valkey™

Maintenance includes:

• Automatic installation of DBMS updates and patches for hosts (including for stopped clusters).
• Scheduled automatic storage expansion.
• Other maintenance activities.

A major DBMS version update is not part of maintenance. For more information about major version changes, see Valkey™ version upgrade.

Maintenance windowMaintenance window

You can set your preferred maintenance start time using the Yandex Cloud interfaces (management console, CLI, Terraform, and API) when creating or updating a cluster:

• The At any time option (default) allows performing maintenance at any time.
• The By schedule option allows you to select the day of the week and UTC time interval for the maintenance. For example, you can choose a time when the cluster is least loaded.

Both active and stopped clusters are subject to maintenance. Maintenance operations may include DBMS updates, applying patches, etc.

In the management console, you select the maintenance start time as an hour interval. In other interfaces, you specify this interval by its sequence number, from 1 to 24.

For example, to start maintenance in the interval from 00:00 to 01:00, put 1; from 04:00 to 05:00, 5.

Maintenance workflowMaintenance workflow

The Yandex Managed Service for Valkey™ cluster maintenance workflow depends on the number of hosts and sharding.

Non-sharded clusterNon-sharded cluster

The maintenance procedure is as follows:

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

How maintenance impacts a clusterHow maintenance impacts a cluster

Depending on its type, maintenance can impact your cluster as follows:

• Show little to no impact on database users.
• Break database connections in place, forcing clients to re-establish their connections.
• Make your cluster read-only for a while.
• Restart the master and trigger master failover to one of the replicas.
• Cause master host failover in the cluster, making the database read-only for a while.

Maintenance tasks have an estimated duration and completion date. These time frames are calculated based on historical data from similar operations. The actual completion times may vary depending on your cluster.