Monday, August 24, 2009

Public folders on a CCR cluster

Microsoft has long stated that locating a public folder database on a CCR cluster in an organization where there is more than public folder database is no supported. Bharat Suneja summarizes this nicely in Cluster Continuous Replication and Public Folders. As with many things that Microsoft says are unsupported but that actually works, I took this to be more of a guideline than a hard and fast rule.

In one of my Exchange environments, we have a lot of regional offices with between 1,000 and 3,000 users. In the 1,000 user location, we did not want to invest additional hardware in a dedicated public folder server so we threw the public folder database on the CCR cluster. During testing that we move the clustered mailbox server (CMS) from node to the other, the public folder database moved just fine.

You guessed it, the active node failed a few weeks ago and the public folder database did not remount. We could not get it to mount at all. Period. End of story. Kaput. Dead database. I had a PSS engineer sitting right next to me and he could not rescue it either. Exchange Server 2007 SP1 is apparently hard coded not to allow the database to be recovered, even if you accept a lossy failover.

So, the moral of the story. If you have more than one public folder database in your organization, do NOT put it on a CCR cluster.



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