The Information Store process performs the following maintenance tasks:
Background cleanup is the process of reclaiming empty space used by deletedfolders, messages, and attachments. There is a registry variable thatcontrols the rate at which this task runs (not exposed in the MicrosoftAdministrator 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 (alsoexposed in the Microsoft Exchange Administrator Program on the DiagnosticLogging 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 is a function of the JET database engine, and is notunder the stores control. There is some amount of online compaction thatgoes on in the background, as needed. This process cleans up the space madeavailable by background cleanup. There are times that compaction will notbe able to efficiently keep up and it will log the following Event ID inthe 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 InformationStore database should be scheduled and performed. Offline defragmentationis performed by using the Edbutil.exe utility with the "/d" option. Thisprocess is performed against each database separately (Priv.edb for theprivate store, Pub.edb for the public store). For more information onperforming offline defragmentation, see the Microsoft Exchange ServerAdministrator'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:
XADM: ESEUTIL command line parameters
There is a schedule page for checking user's storage limits. It islocated in the Site's Configuration Container in the properties of theInformation Store Site Configuration object under the Storage Warnings tab.A separate background thread that is launched according to the schedulepage 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 forthe duration. It performs a sequential list of tasks much like ISmaintenance.
- 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 1and 24 hours, depending on the task.
A number of other background activities happen at scheduled or regularintervals, such as public folder replication, flushing of cached per userread/unread info, expiration of unread messages, and so on. In general,these functions allocate a thread when the task starts and free it when itcompletes.