Recipe6.17.Shrinking a Database That Exceeds the 16 GB Size Limit for Standard Edition

Recipe 6.17. Shrinking a Database That Exceeds the 16 GB Size Limit for Standard Edition

Problem

You have the Standard Edition of Exchange 2000 or Exchange Server 2003, and your mailbox database has reached the 16 GB limit so it keeps dismounting.

Solution

Using a graphical user interface

1. Open the Registry Editor (regedit.exe).

2. Navigate to:

   HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Services\MSExchangeIS

   Beneath that key, you'll see a key with the name of your Exchange server; expand it.

3. Under the Exchange server key, you'll see a key whose name is comprised of the word "Private" plus a long hexadecimal number.

4. Add a new REG_DWORD value named Temporary DB Size Limit Extension; give it a value of 1. This temporarily increases the size limit for the mailbox database to 17 GB.

5. Optionally, stop the SMTP service to keep new mail from being delivered from the outside world and pushing your store over its new limit.

6. Mount your mailbox store, as described in Recipe 6.7.

7. Remove unneeded or unwanted data from the mailbox database. This usually involves emptying the Deleted Items folder and throwing away old mail, and it normally has to be done by your users. You can cheat and use the Mailboxes node in ESM to figure out which mailboxes are the largest and focus on cleaning them first. A better way to perform this sort of maintenance is to use the Mailbox Manager, discussed in Recipe 5.26.

8. Open the Properties dialog box for the mailbox store and switch to the Limits tab.

9. Enter 0 into the Keep deleted items for (days) field and click Apply.

10. Switch to the Database tab, click the Customize button; modify the online maintenance schedule to start immediately (e.g., at the next available time period), and click OK (see Recipe 6.15).

11. Wait for online maintenance to complete, as evidenced by the presence of event ID 1221 (see Recipe 6.10).

12. Follow the steps in Recipe 6.16 to perform an offline defragmentation of the database.

Discussion

The standard version of Exchange has long had a 16 GB limit; the only real change between Exchange 5.5 and Exchange 2000 and Exchange Server 2003 is that the older version allowed you to have only one database, and the newer versions allow one SG with two databases: one private and one public, each limited to 16 GB. The simplest way to override the capacity limitations is to install the Enterprise version of Exchange over the existing version; this is a simple and nondestructive operation that follows the same process described in Recipe 2.12. Failing that, you can use the procedure above to temporarily increase the size limit to 17 GB, which buys you some time during which your users should clear out some of their old mail. Step 9 will force the store not to keep any previously deleted items in the deleted item retention pool, but they won't actually be removed until the next time the online maintenance task runs. Once it runs, the store will purge all previously deleted items, and you'll have back as much free space as you can get without defragmenting the database.

See Also

Recipe 2.14 for upgrading to the Enterprise edition of the same version of Exchange; Recipe 6.7 for remounting the mailbox database, Recipe Recipe 6.10 for determining when online maintenance has finished, Recipe 6.15 for controlling the online maintenance schedule, and MS KB 828070 (Exchange Server Mailbox Store Does Not Mount When the Mailbox Store Database Reaches the 16-GB Limit).