Specifications

Best Practices for Virtualizing and Managing Exchange 2013

Continuing this example, even though Mailbox Server 1 was down for a short period of time, the level of

built-in high availability in Exchange 2013, at the DAG level, ensures that users are still able to access

information and connect to their mailboxes via Mailbox Server 2, which was still running during the

outage of Hyper-V Host 1 (Figure 37).

Figure 37: Reestablishing the DAG after failing over Mailbox Server 1 on another host

This dual layer of availability—specifically, combining Exchange-level availability with host-level

availability—means that within a few minutes, both VMs will be fully online and the administrator can

then rebalance the databases within the DAG, thereby restoring the highest levels of availability that were

experienced before the outage. Whilst we’ve focused on the DAG here, the information is equally

applicable to the CAS Array to distribute the CAS functionality across multiple VMs.

With the Exchange 2013 virtual machines now stored on a Hyper-V cluster, individual virtual machines can

be moved around the cluster using live migration.

Best Practices and Recommendations

When performing live migration of DAG members, follow these key points:

 If the server offline time exceeds five seconds, the DAG node will be evicted from the

cluster. Ensure that the hypervisor and host-based clustering use the Live Migration

technology in Hyper-V to help migrate resources with no perceived downtime.

 If you are raising the heartbeat timeout threshold, perform testing to ensure that

migration succeeds within the configured timeout period.

 On the Live Migration network, enable jumbo frames on the network interface for each

host. In addition, verify that the switch handling network traffic is configured to support

jumbo frames.