Exchange database online maintenance schedule is set to Never

[This topic is intended to address a specific issue called out by the Exchange Server Analyzer Tool. You should apply it only to systems that have had the Exchange Server Analyzer Tool run against them and are experiencing that specific issue. The Exchange Server Analyzer Tool, available as a free download, remotely collects configuration data from each server in the topology and automatically analyzes the data. The resulting report details important configuration issues, potential problems, and nondefault product settings. By following these recommendations, you can achieve better performance, scalability, reliability, and uptime. For more information about the tool or to download the latest versions, see "Microsoft Exchange Analyzers" at]  

Topic Last Modified: 2011-01-26

The Microsoft® Exchange Best Practices Analyzer Tool queries the Active Directory® directory service to determine the value for the activationSchedule attribute on the mailbox stores and public stores. If the Analyzer tool finds that the value resolves to "Never" for activationSchedule, a warning is displayed.

The activationSchedule attribute represents the setting for the online database maintenance schedule. Online database maintenance in Exchange Server is very important. During this interval, tasks such as the following are performed:

  • Dumpster cleanup (the deletion of messages that have passed their deleted item retention date)

  • Public folder expiry (messages in public folders that are older than a certain date are expired)

  • Deleted mailbox cleanup and online defragmentation (database objects that are no longer being used are detected and removed, thereby making additional database space available)

These processes keep the Exchange Server computer healthy and the performance stable. Online maintenance should be set to run for at least four hours every day. Not doing this causes a performance decrease over time.

It is recommended that you configure online database maintenance to run on every database (mailbox store or public folder store) for four hours every day. Stagger the online maintenance intervals and the backup schedules. For example, if backup runs from midnight to 2:00 A.M., run online maintenance from 3:00 A.M. to 7:00 A.M.

This is important because online maintenance does not start if the backup session is still running. If an overlap occurs, backup takes precedence over maintenance. In this case, Exchange checks every 15 minutes to see whether backup is finished. After backup finishes, maintenance starts.

There are 18 tasks that the store preforms to run maintenance. When a task is started, it completes the task regardless of the maintenance timing window. However, maintenance does not begin a new task if the timing window expires. Therefore, in some cases, not all tasks are finished in a given maintenance interval. If maintenance is ended early, it will begin where it ended during the next maintenance cycle.

  1. Open Exchange System Manager.

  2. Expand Servers, and then expand the server that you want to work with.

  3. Expand the storage group that you want to work with.

  4. In the list of available data stores in the details pane, right-click the store that you want to work with, and then click Properties.

  5. In the Store Properties dialog box, click the Database tab.

  6. Do one of the following:

    • In the Maintenance interval list, select an interval.

    • Click Customize to access the Schedule dialog box, and then create a custom interval.

  7. Click OK.

  1. Open Exchange Management Console.

  2. Expand Server Configuration and then select the server that you want to work with.

  3. Expand the storage group that you want to work with.

  4. Right-click the store that you want to work with, and then click Properties.

  5. On the General tab, click the Maintenance schedule list. Then, click an interval or click Customize to create a custom schedule.

For more information about online maintenance database tasks, see Microsoft Knowledge Base article 159196 XADM: Tasks Controlled by the IS Maintenance Schedule.