Modify a Database Size Limit


Applies to: Exchange Server 2010 SP3, Exchange Server 2010 SP2

You can use Registry Editor to modify a database size limit in Microsoft Exchange Server 2010. The default database size limit for Exchange 2010 Standard Edition is 1024 gigabytes (GB). There is no default database size limit for the Exchange 2010 Enterprise Edition. The Exchange store checks any database size limits periodically and dismounts a database when the size limit is reached. You can modify the database size limit by adding or changing a value in the registry.


When you change this setting, this change is propagated to all servers that host a copy of this database.

Looking for other management tasks related to mailbox databases? Check out Managing Mailbox Databases.

Use Registry Editor to Modify a Database Size Limit

If you change the size limit of your Exchange databases, you may want to evaluate your Exchange database backup and restore plan. Specifically, if you increase the size limit of the Exchange databases, test your backup and recovery operations using the new database size limits to make sure that you can still meet your service level agreements (SLAs).


Incorrectly editing the registry can cause serious problems that may require you to reinstall your operating system. Problems resulting from editing the registry incorrectly may not be able to be resolved. Before editing the registry, back up any valuable data.

  1. Start Registry Editor (regedit).

  2. Locate the following registry subkey:

    HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Services\MSExchangeIS\<Server Name>\Private-<database GUID>


    You can get the GUID of a database by running the following command in the Exchange Management Shell: Get-MailboxDatabase -Identity "<database name>" | Format-Table Name, GUID

  3. If the Database Size Limit in GB DWORD exists for the subkey, change its value to the desired size in gigabytes.

  4. If the Database Size Limit in GB DWORD doesn't exist for the subkey, create a new DWORD with that name, and then set its value to the desired size in gigabytes.

For more information about managing databases, see Managing Mailbox Databases.

To learn more about Registry Editor, see Registry Editor overview.

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