Exchange General: Maximum database sizes

Here is a list of the maximum database sizes for the various Exchange versions. Starting with Exchange 2003 up to the current version Exchange 2010.

The information relates to a single database, whereby the size of the database is made up of EBD and STM. By default, Exchange 2003 with Service Pack 2 installed only supports a maximum database size of 18 GB. However, the maximum size can be increased via the registry.

Attention: This only applies to Exchange Server 2003 with Service Pack 2!

The database can be increased to a maximum of 75 GB via Regedit by navigating to the key

HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Services\MSExchangeIS\\Private-

And create a new REG-DWORD, or edit it if it already exists:

"Database size limit in GB" (without the quotes)

You can now specify the maximum database size with the DWORD specified above. Values between 18 and 75 are valid. When changing the value, make sure that decimal numbers are entered.

A second REG-DWORD defines the warning level when the maximum size is reached:

"Database Size Buffer in Percentage"

Values between 1 and 100 are valid. This value specifies as a percentage when a warning is generated in the event log. Example:

If the maximum database size has been set to 70 GB and "Database Size Buffer in Percentage" has the value 10, a warning is generated if the database is 63 GB in size (70GB-10%=63GB).

A little tip: It is better not to set the maximum size immediately. If the database grows to 75 GB and you find out too late, you can no longer increase it. So it's better to only set 70 GB at first. If the database then fills up, you can increase it by another 5 GB. However, you should then quickly think about how to reduce the size of the database. In most environments where no limits are set for the maximum mailbox size, I have noticed that most of the storage space in the database is only used by a few users. So in most cases it is enough to archive a few mailboxes and configure the mailbox size limits.