XADM: IS Maintenance Tasks Not on IS Schedule

 Last reviewed: September 29, 1997
Article ID: Q159306
The information in this article applies to:
  • Microsoft Exchange Server, version 4.0

SUMMARY

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 information on the tasks controlled by the IS Maintenance Schedule see the following article in the Microsoft Knowledge Base: 

   ARTICLE-ID: Q159196
   TITLE     : XADM: Tasks Controlled by the IS Maintenance Schedule

MORE INFORMATION

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): 

   HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Services\MSExchangeIS
   \ParametersPublic\Background Cleanup (value in milliseconds)

   HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Services\MSExchangeIS\
   ParametersPrivate\Background Cleanup (value in milliseconds)
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): 

   HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Services\MSExchangeIS
   \Diagnostics\Private\General\Background Cleanup"

   HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Services\MSExchangeIS
   \Diagnostics\Public\General\Background Cleanup"

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: 

   Event ID = 63
   Source = EDB
   Category = General
   Description = MSExchangeIS ((44)) Background Cleanup skipped pages.
   Database may benefit from defragmentation
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.

Storage Warnings

There is a schedule page for checking user's storage limits, this 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.

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. 

Keywords          : XADM kbusage
Version           : WinNT:4.0
Platform          : winnt
Issue type        : kbhowto

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Last reviewed: September 29, 1997
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