Increase maximum database size for mailbox store

Topic Last Modified: 2005-12-15

The Microsoft® Exchange Server Analyzer Tool queries the CIM_DataFile Microsoft Windows® Management Instrumentation (WMI) class to determine the following information:

The full path for the Exchange database files.
The current size of the mailbox store.

The Exchange Server Analyzer also queries the Win32_OperatingSystem WMI class to determine additional information:

The version of the Windows operating system that is running on the Exchange server.
The version of Exchange Server that is installed.
The edition of Exchange Server that is installed.
The service pack level version for Exchange Server.

Finally, the Exchange Server Analyzer also reads the following registry entry to determine whether the Database Size in Gb value has been set:

HKEY_LOCAL_MACHINE\System\CurrentControlSet\Services\MSExchangeIS\<ServerName>\Private-<MailboxStoreGUID>

The Exchange Server Best Practices Analyzer displays an error if the following conditions are true:

The server is running Exchange Server 2003.
The service has Service Pack 2 for Exchange Server 2003 installed.
The Exchange Server database size is larger than 16 gigabytes (GB).
The Database Size in Gb registry value has not been set.

This error indicates that the identified Exchange database is close to its size limit. Service Pack 2 for Exchange Server 2003 raises the database storage limits from 16 GB to 75 GB. However, to use the new limits you must manually add the Database Size in Gb registry value on the Exchange Server.

Important:
This article contains information about editing the registry. Before you edit the registry, make sure you understand how to restore the registry if a problem occurs. For information about how to restore the registry, view the "Restore the Registry" Help topic in Regedit.exe or Regedt32.exe.

To correct this error by adding the Database Size in Gb registry value

On the computer that is running Exchange Server, open a registry editor such as Regedit.exe or RegEdt32.exe.
Navigate to: HKLM\System\CurrentControlSet\Services\MSExchangeIS\<ServerName>\Private-<MailboxStoreGUID>
Right-click MailboxStoreGUID, point to New, and then click DWORD Value.
For the new value name, type Database Size Limit in Gb.
Double-click Database Size Limit in Gb. In Value data, type an appropriate value for maximum database size in GB. Click OK.
Right-click MailboxStoreGUID, point to New, and then click DWORD Value.
For the new value name, type Database Size Buffer in Percentage.
Double-click Database Size Buffer in Percentage. In Value data, type a value between 1 and 100 to specify when you want events to be logged to warn you that you are nearing the maximum size for a database. Click OK.

Note:

The default value of 10 will cause warning events to be logged when you have 10 percent capacity left before you reach the maximum size for that database.
Right-click MailboxStoreGUID, point to New, and then click DWORD Value.
For the new name, type Database Size Check Start Time in Hours From Midnight.
Double-click Database Size Check Start Time in Hours From Midnight. In Value data, type a value between 0 and 23 to specify when you want Exchange to look at the database size. Click OK.

Note:

The default value of 5 causes Exchange Server to look at the database size at 5 hours after midnight (05:00).
Close the registry editor.

Note:
The default value of 10 will cause warning events to be logged when you have 10 percent capacity left before you reach the maximum size for that database.

Note:
The default value of 5 causes Exchange Server to look at the database size at 5 hours after midnight (05:00).

Before you edit the registry, and for information about how to edit the registry, see the Microsoft Knowledge Base article 256986, "Description of the Microsoft Windows registry" (http://go.microsoft.com/fwlink/?linkid=3052&kbid=256986).

For more information about how to configure and manage Exchange Server database size limits, see "Database Size Limit Configuration and Management" (http://go.microsoft.com/fwlink/?LinkId=57029).

For information about maximum database size for Exchange Server 2003 Standard Edition and Exchange 2000 Server Standard Edition, see the Knowledge Base article 828070, "Exchange Server Mailbox Store does not mount when the Mailbox Store database reaches the 16-GB limit" (http://go.microsoft.com/fwlink/?linkid=3052&kbid=828070).

For more information about SP2 for Exchange Server 2003, see the Exchange Server 2003 Service Pack 2 Web site, "Why Try Service Pack 2 for Exchange Server 2003?" (http://go.microsoft.com/fwlink/?LinkId=52073).