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Q. I'm receiving errors in the Application event log about my Microsoft Exchange Server 2003 Store, and the Exchange 2003 database has gone offline and won't mount. Do you know what's causing these problems?

A. To identify the source of the problems, first look for the following error events in the Application log:

Event Type: Error
Event Source: MSExchangeIS
Event Category: General
Event ID: 1112
Date: 10/5/2004
Time: 11:30:49 AM
User: N/A
Computer: OMEGA
The database "First Storage Group\Mailbox Store (OMEGA)" has reached
the maximum allowed size. Attempting to unmount the database.

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Event Type: Warning
Event Source: ESE
Event Category: Space Management
Event ID: 445
Date: 10/5/2004
Time: 11:30:49 AM
User: N/A
Computer: OMEGA
Information Store (10228) First Storage Group: The database
E:\mdbdata\priv1.edb has reached its maximum size of 16383 MB. If the
database cannot be restarted, an offline defragmentation may be
performed to reduce its size.

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These events indicate that you're running Exchange Server 2003, Standard Edition (the errors can also occur in Exchange 2000 Server, Standard Edition), which has a maximum database size of 16GB, including the streaming file. After the database reaches this size, the Store will unmount and can't be mounted again until you either upgrade to Exchange Server 2003, Enterprise Edition or Exchange 2000 Server, Enterprise Edition (both of which have a much higher database size limit) or reduce the size of the database.

If upgrading isn't an option for you, you can probably reduce the size of the database by performing an Exchange offline defragmentation using the Extensible Storage Engine (ESE) utility--eseutil.exe. You can find eseutil.exe in the Exchange installation bin folder (e.g., \exchsrvr\bin). Run the Eseutil command with the /d parameter and the database name:

eseutil /d c:\exchsrvr\mdbdata\priv1.edb

Although you specify only the database file, Exchange Server will also automatically defragment the associated streaming file. If you don't want to defragment the streaming file, specify the /i switch on the Eseutil command. If the streaming file isn't in its default location, you can use the /s switch to specify its location. By default, the Eseutil defragmentation creates a new database on the same volume as that on which the Eseutil utility resides to temporarily store the defragmented information. To ensure that you have sufficient free space, you can use the /t switch to specify where the temporary database file should be created.

After the defragmentation is finished, the Exchange Server database should be small enough to be mounted. You should now take one of these three actions:

  1. Establish mailbox limits to ensure that the database can't grow too large. You could also implement policies to automatically delete mail that's older than a specified number days; however, you should notify users of such policies ahead of time and make sure that the policies conform to legal email retention requirements.
  2. Upgrade to Exchange 2003 Enterprise or Exchange 2000 Enterprise, which allow larger databases (and more of them).
  3. Add Exchange 2003 Standard or Exchange 2000 Standard servers and distribute the mailboxes across them.

These actions can help you avoid the database-size errors you described. You should also perform regular checks on the database state so that you're aware of potential problems.

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