Maintenance window in Azure SQL Database

  • Article

Applies to: Azure SQL Database

The maintenance window feature allows you to configure maintenance schedule for Azure SQL Database and Azure SQL Managed Instance resources making impactful maintenance events predictable and less disruptive for your workload.

Note

The maintenance window feature only protects from planned impact from upgrades or scheduled maintenance. It does not protect from all failover causes; exceptions that might cause short connection interruptions outside of a maintenance window include hardware failures, cluster load balancing, and database reconfigurations due to events like a change in database Service Level Objective.

Advance notifications are available for databases configured to use a nondefault maintenance window. Advance notifications enable customers to configure notifications to be sent up to 24 hours in advance of any planned event.

Overview

Azure periodically performs planned maintenance of SQL Database resources. During a maintenance event, databases are fully available but can be subject to short reconfigurations within availability Service Level Agreements (SLA) for SQL Database.

Maintenance window is intended for production workloads that are not resilient to database reconfigurations and cannot absorb short connection interruptions caused by planned maintenance events. By choosing a maintenance window you prefer, you can minimize the impact of planned maintenance by scheduling it to occur outside of your peak business hours. Resilient workloads and nonproduction workloads can rely on Azure SQL's default maintenance policy.

The maintenance window is free of charge and can be configured on creation or for existing resources. It can be configured using the Azure portal, PowerShell, CLI, or Azure API.

Important

Configuring maintenance window is a long running asynchronous operation, similar to changing the service tier of the Azure SQL resource. The resource is available during the operation, except a short reconfiguration that happens at the end of the operation and typically lasts up to 8 seconds even in case of interrupted long-running transactions. To minimize the impact of the reconfiguration you should perform the operation outside of the peak hours.

Gain more predictability with maintenance window

By default, Azure SQL maintenance policy blocks most impactful updates during the period 8AM to 5PM local time every day to avoid any disruptions during typical peak business hours. Local time is determined by the location of Azure region that hosts the resource and might observe daylight saving time in accordance with local time zone definition.

During maintenance, databases remain available, but some updates may require a failover. The system default maintenance window (5pm to 8am) limits most activities to this time, but urgent updates may occur outside of it. To ensure all updates occur only during the maintenance window, select a non-default option.

You can adjust the window for maintenance updates to a time suitable to your Azure SQL resources by choosing from two non-default maintenance window slots:

  • Weekday window: 10:00 PM to 6:00 AM local time, Monday - Thursday
  • Weekend window: 10:00 PM to 6:00 AM local time, Friday - Sunday

Maintenance window days listed indicate the starting day of each eight-hour maintenance window. For example, "10:00 PM to 6:00 AM local time, Monday - Thursday" means that the maintenance windows start at 10:00 PM local time on each day (Monday through Thursday) and complete at 6:00 AM local time the following day (Tuesday through Friday).

Once the maintenance window selection is made and service configuration completed, planned maintenance occurs only during the window of your choice. While maintenance events typically complete within a single window, some of them might span two or more adjacent windows.

Note

Azure SQL Database follows a safe deployment practice where Azure paired regions are guaranteed to be not deployed to at the same time. However, it is not possible to predict which region will be upgraded first, so the order of deployment is not guaranteed. Sometimes, your primary database will be upgraded first, and sometimes it would be secondary.

  • In situations where your database is enabled for geo-replication or failover groups, and the geo-replication does not align with the Azure region pairing, you should different maintenance window schedules for your primary and secondary database. For example, you can select Weekday maintenance window for your geo-secondary database and Weekend maintenance window for your geo-primary database.

Important

In very rare circumstances where any postponement of action could cause serious impact, like applying critical security patch, configured maintenance window might be temporarily overriden.

Advance notifications

Maintenance notifications can be configured to alert you of upcoming planned maintenance events for your Azure SQL Database. The alerts arrive 24 hours in advance, before maintenance window opens, and at the end of maintenance window. For more information, see Advance Notifications.

Feature availability

Supported subscription types

Configuring and using maintenance window is available for the following offer types: Pay-as-you-go, Cloud Solution Provider (CSP), Microsoft Enterprise Agreement, or Microsoft Customer Agreement.

Offers restricted to dev/test usage only are not eligible (like pay-as-you-go Dev/Test or Enterprise Dev/Test as examples).

Note

An Azure offer is the type of the Azure subscription you have. For example, a subscription with pay-as-you-go rates, Azure in Open, and Visual Studio Enterprise are all Azure offers. Each offer or plan has different terms and benefits. Your offer or plan is shown on the subscription's Overview. For more information on switching your subscription to a different offer, see Change your Azure subscription to a different offer.

Supported service level objectives

Choosing a maintenance window other than the default is available on all SLOs except for the following.

  • SLOs not supported:
    • Azure SQL Database DTU Basic, S0 and S1 tiers
    • DC hardware
    • Fsv2 hardware

Other scenarios:

Azure SQL Database region support for maintenance windows

Choosing a maintenance window for Azure SQL Database other than the default is currently available in the following regions, organized by purchasing model.

Azure Region
China East 2 Yes
China North 2 Yes

Gateway maintenance

To get the maximum benefit from maintenance windows, make sure your client applications are using the redirect connection policy. Redirect is the recommended connection policy, where clients establish connections directly to the node hosting the database, leading to reduced latency and improved throughput.

In Azure SQL Database, any connections using the proxy connection policy could be affected by both the chosen maintenance window and a gateway node maintenance window. However, client connections using the recommended redirect connection policy are unaffected by a gateway node maintenance reconfiguration.

For more on the client connection policy in Azure SQL Database, see Azure SQL Database Connection policy.

Retrieve list of maintenance events

Azure Resource Graph is an Azure service designed to extend Azure Resource Management. The Azure Resource Graph Explorer provides efficient and performant resource exploration with the ability to query at scale across a given set of subscriptions so that you can effectively govern your environment.

You can use the Azure Resource Graph Explorer to query for maintenance events. For an introduction on how to run these queries, see Quickstart: Run your first Resource Graph query using Azure Resource Graph Explorer.

To check for the maintenance events for all SQL databases in your subscription, use the following sample query in Azure Resource Graph Explorer:

servicehealthresources
| where type =~ 'Microsoft.ResourceHealth/events'
| extend impact = properties.Impact
| extend impactedService = parse_json(impact[0]).ImpactedService
| where  impactedService =~ 'SQL Database'
| extend eventType = properties.EventType, status = properties.Status, description = properties.Title, trackingId = properties.TrackingId, summary = properties.Summary, priority = properties.Priority, impactStartTime = todatetime(tolong(properties.ImpactStartTime)), impactMitigationTime = todatetime(tolong(properties.ImpactMitigationTime))
| where eventType == 'PlannedMaintenance'
| order by impactStartTime desc

For the full reference of the sample queries and how to use them across tools like PowerShell or Azure CLI, visit Azure Resource Graph sample queries for Azure Service Health.

Related content