[PS] C:\>Set-MailboxServer sydex1 -DatabaseCopyActivationDisabledAndMoveNow $true
So what actually happens when you do that?
As TechNet explains:
The DatabaseCopyActivationDisabledAndMoveNow parameter specifies whether to prevent databases from being mounted on this server if there are other healthy copies of the databases on other servers. It will also immediately move any mounted databases on the server to other servers if copies exist and are healthy. Setting this parameter won’t cause databases to move to a server that has the DatabaseCopyAutoActivationPolicy parameter set to Blocked.
So the first thing that happens is any active mailbox database copies on the server are moved to another DAG member, as long as:
- Another healthy copy exists to activate
- The DAG member that is hosting the copy does not have an auto activation policy of “Blocked”
Then what? Well, the DatabaseCopyActivationDisabledAndMoveNow property doesn’t prevent database copies being activated on that server again. But if you activate one you’ll see a message like this:
[PS] C:\>Move-ActiveMailboxDatabase -Identity DB01 -ActivateOnServer SYDEX1 WARNING: Server "SYDEX1.exchange2013demo.com" is enabled for DatabaseCopyActivationDisabledAndMoveNow. Moving databases to such servers may be ineffective because the system will automatically attempt to move again as soon as a healthy copy is detected.
In my tests it took only a few minutes for the activate database copy to be moved elsewhere again.
Hopefully that makes it clearer why we perform that step during Exchange 2013 maintenance, and why it is important at the end of the maintenance to set the property back to $false.
[PS] C:\>Set-MailboxServer SYDEX1 -DatabaseCopyActivationDisabledAndMoveNow $false