Recovering a 16GB Mail Database

SBS 2003 currently contains Exchange Server 2003, which has a total database size limit of 16GB for each of the Public and Private stores.

That is not a great deal of storage these days, particularly given the quantity and size of attachments sent and stored with messages. To some extent, pressure is alleviated by Exchange's single instance storage, but it is becoming more common to find databases that have inadvertently hit the 16GB limit triggering the messaging database to shut down and making the store unmountable.

Although Exchange 2003 SP2 increases the data store size to 75GB and the simplest solution is to upgrade the Exchange Server, you may come across instances where this is not possible or practicable.

If you cannot upgrade to Exchange 2003 SP2, you can temporarily increase the size of the data store to 17GB by creating a new Registry value by following these steps:

1.	Open the registry at: [View full width] HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Services\MSExchangeIS\<Exchange Server Name> \Private-<hexadecimal GUID>.
2.	Create a new DWORD: Temporary DB Size Limit Extension.
3.	Set the value data to 1.

Caution

The usual warning about editing the Registry applies. Great care needs to be taken. You should have a known good backup of the Registry and know how to restore it in the event of disaster or lockout.

This is only a temporary solution, however, while you are repairing the database. It is strongly recommended that you stop the Simple Mail Transfer Protocol (SMTP) service and the Microsoft Exchange MTA Stacks service (if it is running) before you mount the Mailbox Store to ensure that additional data does not flow into the database. The next time that the Exchange services are started, the size limit reverts to 16GB.

Use one or more of the following to reduce the size of your database before the size limit reverts to 16GB:

• Have users clean up their mailboxes.

• Remove database content using ExMerge.

• Purge deleted, unused, and nonessential mailboxes.

• Reduce the Deleted Items Retention period. (Setting it to 0 deletes all deleted items.)

Follow these steps to physically reduce the size of the store database. The Mailbox Store is listed in this set of steps, but the same process will work for the Public Folder Store:

1.	Open Exchange System Manager.
2.	Expand Servers, <SBS Server Name>, First Storage Group.
3.	Right-click on the Mailbox Store and select Properties.
4.	Select the Database tab; then click Customize next to Maintenance Interval.
5.	Enable the time area starting with the next 15 minute interval and select several hours past that time in the Schedule window; then click OK.
6.	Wait for the online maintenance task to run. It will start at the next quarter hour and may run for several hours, depending on how much data was deleted prior to running the maintenance.
7.	Monitor the application event log to see when the online maintenance task completes.
8.	After the online maintenance task completes, dismount the Mailbox Store.
9.	Open a command prompt and change into the MDBDATA directory.
10.	Make a copy of the priv1.edb and priv1.stm files to a different location on the sever or another workstation.
11.	Make sure that you have at least 36GB of free disk space on the drive.
12.	Run eseutil /d priv1.edb and wait for it to complete. This could take several hours.
13.	Run isinteg -s <servername> -fix -test alltests at the command line.
14.	Type 1 and press Enter to select the Mailbox Store (note that it must be offline for isinteg to work).
15.	Type Y and press Enter to start the process.
16.	Review the output of the command. If you see any errors or fixes listed for any of the tests, repeat the isinteg command. Continue running the isinteg command until the number of errors and fixes drops to zero, or until the number stays the same on multiple test runs.
17.	Look at the size of the combined database files. If the size of both files is less than 16GB, remount the databases.
18.	Get a backup of the Mailbox Store and then allow users back into Exchange.

Note

The 16GB size limit for the Exchange Private Mailbox Store database and the 16GB size limit for the Exchange Public Mailbox Store database is the sum of the size of both the respective .edb and the .stm files. Exchange System Manager displays only the space used by the .edb file as the mailbox size. It does not include the space that the .stm file uses. Also, when you put a limit on a mailbox, you limit the storage only in the Priv.edb file but not in the Priv.stm file.