April 21, 2010

Multi site DAG failover prevention

Another one of those "gotta post it here otherwise I'll never find it again" things.
You have a 2+1 DAG. The +1 is in a second data centre - well it would be wouldn't it, it's the +1!
Trouble is that the (in your case) second data centre isn't really there for an active/active configuration, i.e. you want control on whether to activate the third copy or have an outage whilst you fix things up. Ordinarily if the two copies in the primary location are down the third is going to come right up. Well, if you've had a link failure in a particular scenario you don't absolutely, positively want to invoke DR. You might want to think about it for a while.

Use: http://technet.microsoft.com/en-us/library/dd351074.aspx to configure the copies so that replication and replay work as designed but never automatically activate.