XADM: IS Maintenance Tasks Not on IS Schedule

The Microsoft Exchange Server Information Store (IS) has many tasks that run in the background and perform maintenance-type operations. This article outlines the maintenance tasks that are not controlled by the IS Maintenance schedule. For additional information on the tasks controlled by the IS Maintenance Schedule, click the following article number to view the article in the Microsoft Knowledge Base:

The Information Store process performs the following maintenance tasks:

Background Cleanup

Background cleanup is the process of reclaiming empty space used by deleted folders, messages, and attachments. There is a registry variable that controls the rate at which this task runs (not exposed in the Microsoft Administrator program): Event logging is controlled by the following registry settings (also exposed in the Microsoft Exchange Administrator Program on the Diagnostic Logging tab for the Private/Public Information Store):

Database Compaction

Database compaction is a function of the JET database engine, and is not under the stores control. There is some amount of online compaction that goes on in the background, as needed. This process cleans up the space made available by background cleanup. There are times that compaction will not be able to efficiently keep up and it will log the following Event ID in the application log: This Event ID means that an offline defragmentation of the Information Store database should be scheduled and performed. Offline defragmentation is performed by using the Edbutil.exe utility with the "/d" option. This process is performed against each database separately (Priv.edb for the private store, Pub.edb for the public store). For more information on performing offline defragmentation, see the Microsoft Exchange Server Administrator's Guide, Chapter 17.

Note In Microsoft Exchange Server 5.5 and in Microsoft Exchange 2000 Server, Eseutil.exe replaces Edbutil.exe. For additional information on using Eseutil, click the following article number to view the article in the Microsoft Knowledge Base:

Storage Warnings

There is a schedule page for checking user's storage limits. It is located in the Site's Configuration Container in the properties of the Information Store Site Configuration object under the Storage Warnings tab. A separate background thread that is launched according to the schedule page and runs until completion performs this check.

Note In Exchange 5.5, the Information Store Site configuration changes automatically whenever daylight-saving time changes, but it does not change whenever the IS Maintenance schedule changes.

Periodic Background Activities

This task runs at 10-minute intervals, and has a thread allocated to it for the duration. It performs a sequential list of tasks much like IS maintenance.

• Re-read Information Store storage quota values from the Microsoft Exchange Directory.
  
  
• Flush table row counts to the database.
  
  
• Flush cached Exchange Server Directory information.
  
  
• Re-read per-user Mailbox storage quota values from the Exchange Server Directory.
  
  
• Perform other miscellaneous store functions.

These tasks, like IS maintenance, do not all run at 10-minute intervals; each task has its own minimum frequency value, which is usually between 1 and 24 hours, depending on the task.

A number of other background activities happen at scheduled or regular intervals, such as public folder replication, flushing of cached per user read/unread info, expiration of unread messages, and so on. In general, these functions allocate a thread when the task starts and free it when it completes.