How much downtime can I expect for my RDS for SQL Server Single-AZ or Multi-AZ instance scheduled maintenance window?

Short description

AWS performs periodic maintenance to the physical host hardware, database version, or the operating system of your Amazon RDS for SQL Server instance. Before maintenance occurs, you receive an email notification. This email details the affected resources and the scheduled timeframe of the maintenance.

Estimated downtime differs for Single-AZ instances and Multi-AZ instances. The downtime that you experience might change based on the type of maintenance that's performed.

Resolution

Note: If you receive errors when you run AWS Command Line Interface (AWS CLI) commands, then see Troubleshoot AWS CLI errors. Also, make sure that you're using the most recent AWS CLI version.

You can check the AWS Health Dashboard to confirm if scheduled maintenance will incur downtime. The Health Dashboard will state if this maintenance involves downtime for the affected instances.

View past or pending maintenance actions

To review past scheduled maintenance for your RDS instances, see viewing RDS events.

To view pending maintenance actions for your RDS instances with the AWS Management Console or the AWS CLI, complete the following steps:

1. Open the Amazon RDS console.
2. In the navigation pane, choose Databases.
3. Select the RDS for MySQL DB instance or DB instance that you want to view maintenance actions for.
4. Choose the Maintenance & backups tab to view the list of pending maintenance actions under the Pending maintenance section or run the following command:

   $ aws rds describe-pending-maintenance-actions --region example-region-name

Note: Make sure to replace example-region-name with your specified Region name.

You can adjust the time of your maintenance window. For more information, see Adjusting the preferred DB instance maintenance window.

Hardware maintenance downtime

Single-AZ instances: The instance is unavailable for several minutes while maintenance is performed. The exact time the maintenance takes varies based on the instance class type and database size.

Multi-AZ instances: Multi-AZ instances are unavailable for the time that it takes the primary instance to failover. This failover takes no more than 60 seconds. If only the secondary Availability Zone is affected by the maintenance, then there is no failover or downtime.

Database engine upgrade downtime

Single-AZ instances: The instance is unavailable for several minutes while maintenance is performed. The exact time the maintenance takes varies based on the instance class type and database size.

Multi-AZ instances: In Multi-AZ instances, both the primary and standby instances are upgraded. Amazon RDS performs rolling upgrades. The outage lasts only for the duration of a failover after the secondary is upgraded and promoted to primary. The original primary then becomes the secondary and has the upgrade applied to it.

OS maintenance downtime

Single-AZ instances: The instance is unavailable for several minutes while maintenance is performed. The exact time the maintenance takes varies based on the instance class type and database size.

Multi-AZ instances: In Multi-AZ RDS instances, both the primary and standby instances are upgraded. RDS performs rolling upgrades. The outage last only for the duration of a failover after the secondary is upgraded and promoted to primary. The original primary then becomes the secondary and has the upgrade applied to it.

Related information

What do I need to know about the Amazon RDS maintenance window?