This is part 4 in the series of posts on Hyper-V Replicas where we will review new features and improvements added to Hyper-V Replicas in Server 2012 R2. Here are links to part 1,  part 2, part 3 of this series. The ability to replicate VMs was originally added in Server 2012, but Microsoft has added significant functionality in R2. In this post I will discuss:

  1. Replication frequency
  2. Recovery points
  3. Extended replication
  4. Enhanced Linux guest OS support

Replication Frequency

Previously, replication frequency was not configurable and fixed at an interval of every five minutes. Now, replication frequency is configurable to three selections: 30 seconds, five minutes, and fifteen minutes. Five minutes is still the default, but if your recovery point objective (RPO) for your disaster recovery strategy is high, meaning data loss is expensive to your business, 30 seconds provides a more granular platform to make sure data and transactions are replicated to your DR site. If bandwidth is more of a premium to you, and your business is not as transactional in nature, a higher replication frequency is available.

Recovery Points

Replicas can now have up to 24 recovery points for replicated VMs (one per hour) over the prior release limit of 15 (one per hour).

Extended Replication

Extended replication allows site > site > site replication. This provides an additional layer of redundancy for businesses which place high importance on continuity in the event of a disaster. There are limitations of the extended Replica server, however, in that it does NOT offer application-consistent replication for the extended Replicas, and the extended Replica server must use the same VHDs as the Replica server. Think of the extended Replica as a last resort safety net, as you can failover to it only when the primary and Replica servers are down. You can, however, perform test failovers at the extended site.

Enhanced Linux Guest OS Support

The Hyper-V Replica feature has always been OS agnostic; however, there was no ability to have file system consistency in snapshots. With 2012 R2, file system consistency is now provided for Linux VM snapshots. Also, when performing failover of Linux Replicas, you can inject IP addresses as part of the failover workflow.

You can review the entire list of Server 2012 R2 enhancements here.

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