Teaching an Old Dog a New Trick: Exchange 2003 and the File Share Witness

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About two-and-a-half years ago, I blogged about about a new feature in Exchange Server 2007 called Cluster Continuous Replication (CCR). In that blog, I explained that because CCR does not use shared storage for the Exchange data, we wanted to make sure we didn't need shared storage anywhere in the cluster. The Exchange team worked very closely with the Windows Cluster team to create a new type of quorum device based on the Majority Node Set (MNS) quorum model called an MNS quorum with File Share Witness (FSW). The Windows Cluster team originally delivered the MNS+FSW quorum model in the form of QFE (hotfix) 921181 back in July 2006, several years after the release of Exchange Server 2003.

From time to time, we get questions from customers asking if the MNS+FSW quorum model can be used for clustered mailbox servers running Exchange 2003 on Windows 2003. The answer is Yes, you can!  And yesterday, we updated our Exchange 2003 content to reflect this.

Specifically, we now state:

When deployed in a multi-node cluster, Exchange Server 2003 requires one of the following quorum models:

  • Single quorum device (shared disk quorum)
  • Majority Node Set (MNS)
  • Majority Node Set with File Share Witness (MNS+FSW)

So, even though Exchange 2003 came out well before the MNS+FSW quorum model, you can still use that quorum model for your multi-node clusters running Exchange 2003 on Windows 2003.