Specifications

Best Practices for Virtualizing and Managing Exchange 2013
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With DAGs, Exchange 2013 can work as a cluster-aware application to provide better availability and
resiliency for Exchange 2013 mailboxes in a virtualized environment (Figure 36). (For more information,
see the Mailbox Server Role subsection above.)
Figure 36: Creating Exchange 2013 Mailbox servers
In this example, a three-node Hyper-V cluster is connected to some shared storage. This storage could be
an iSCSI or FC SAN, or with Windows Server 2012 Hyper-V, it could be an SMB 3.0 file share on which the
Exchange 2013 VHDX files are stored. Exchange 2013 as an application or workload has no requirement
for shared storage; however, the Hyper-V layer itself, for resiliency through failover clustering, requires
some form of shared storage to store the virtual disks of the virtual machines.
On top of this Hyper-V cluster are two virtual machines, hosting the Mailbox role and are configured in a
DAG. The virtual machines are split across the hosts, with Mailbox Server 1 on Hyper-V Host 1, and
Mailbox Server 2 on Hyper-V Host 2. This is currently optimal in the sense that if you were to lose either
of the Hyper-V hosts running the Exchange 2013 virtual machines, the entire Exchange 2013 DAG would
not be taken down.
As an example, say you were to lose Hyper-V Host 1. Mailbox Server 1 also would be temporarily lost, but
would automatically restart on another available node on the cluster. When restarting the virtual
machines, Failover Cluster Manager looks at the available resources in the cluster and places the restarting
virtual machines on the most appropriate host—again, all without administrator intervention.
Best Practices and Recommendations
Use the Failover Priority setting to ensure that, upon failover, the Exchange 2013 virtual machines
start in advance of other, less important virtual machines.