Exchange Server 2013, 2016 and 2019 Standard Edition can't mount databases that are larger than 1024 GB
Original KB number: 3059008
Summary
This issue occurs because the default database size limit for Microsoft Exchange Server 2019 Standard Edition, Exchange Server 2016 Standard Edition and Exchange Server 2013 Standard Edition is 1,024 gigabytes (GB). There is no default database size limit for the Enterprise Edition. The Exchange store checks database size limits periodically and dismounts a database when the size limit is reached. Therefore, this issue may occur after the database is automatically dismounted.
Additionally, when you perform a failover of the database, the failover fails.
Note
The database maximum size is hard-coded as 1,024 GB in the event, even though you may have changed it to a higher value in the registry.
Resolution
In order to have the full functionality of the Exchange database availability group (DAG) again, you must buy an Enterprise Edition license and apply it to the server.
Workaround
Important
Follow the steps in this section carefully. Serious problems might occur if you modify the registry incorrectly. Before you modify it, back up the registry for restoration in case problems occur.
To mount the database again, and to prevent the database from being automatically dismounted, follow these steps:
Start Registry Editor.
Locate the registry subkey:
HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Services\MSExchangeIS\<Server Name>\Private-<database GUID>
.Note
You can retrieve the GUID of a database by running the following command in the Exchange Management Shell:
Get-MailboxDatabase -Identity "<database name>" | Format-Table Name, GUID
If the
Database Size Limit in GB
DWORD value exists for the subkey, change it to the size that you want, in GB.If the
Database Size Limit in GB
DWORD value does not exist for the subkey, create a new DWORD value with that name, and then set its value to the size that you want, in GB.Mount the database on the server by using Exchange Management Shell and the
-Force
switch.
Note
- When you change this setting, the change is propagated to all servers that host a copy of this database.
- This registry key may be deleted after an Exchange cumulative update is applied.
- This registry setting still doesn't allow the automatic failover of databases within the DAG. You must use the
-Force
switch when you mount the database with this registry setting in place.
Status
Microsoft has confirmed that this is a problem.