Wednesday, April 28, 2004

How often do I need to perform offline Exchange maintenance

A favorite question I get from students is: "How often should I perform offline Exchange database maintenance?"

Quite simply: Never.

Exchange 5.5 SP4 and later's online maintenance utilities are good enough that they keep the database tidy and defragmented without ever shutting it down. As deleted items are purged from the database file, the file is rearranged so all of the extra space is contiguous. This is called whitespace and it is done during nightly online maintenance. This MUST complete each night.

The database file(s) never shrink, though. The whitespace is filled by the next modifications to the database.

If you have recently deleted a lot of messages or a lot of mailboxes (and the deleted mailbox retention and deleted item retention time has past), then Event Id 1221 (seen nightly in the event logs after online maintenance) will tell you approximately how much whitespace is in the database file.

If you can get back 20 to 25 percent of the total size of the file, THEN you might want to consider shutting down your system and performing an ESEUTIL /D to defrag the database. This WILL reduce the size of the database file(s). Always do a backup full BEFORE and AFTER system maintenance, though. Just in case.

Though the ISINTEG utility may report errors or fixes, you generally don't need to run this if you users are not reporting problems or you don't see problems in your event logs.

There are usually better things for you to do with your after-hours time than come in to work and shut your Exchange server down. If you have to get away from your spouse or significant other, then come in and work in documentation or disaster recovery plans. :-)

Keywords: Exchange 5.5 2000 2003 offline maintenance ESEUTIL ISINTEG errors defragment compact


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