Hyper-V Replica is a new feature of Hyper-V that was introduced in Windows Server 2012. In this article, I’ll cover the new features included in Server 2012 R2.

As we covered previously on 4sysops, Failover Clustering of Hyper-V nodes provides high availability for virtual machines running on the cluster. Using a Hyper-V Failover Cluster allows organizations to keep their virtual workloads running with little or no downtime during planned or unplanned outages of nodes within the cluster since VMs can be Live or Quick Migrated to other active nodes.

One of the problems not addressed with Hyper-V Failover Clusters is the ability to handle Disaster Recovery scenarios. If your organization’s primary data center, office, or building hosting your virtual workloads encounters any kind of outage, those services may become unavailable to end users. While there are various storage technologies that allow organizations to replicate datastores between physical locations, many of these products can be cost prohibitive and/or difficult to implement.

This is where Hyper-V Replica comes in. Hyper-V Replica is a new feature in Windows Server 2012 that has been improved in Server 2012 R2 and is included as part of the Hyper-V role. So if you’re running Hyper-V on Windows Server 2012 or higher, Replica is already available to you with no additional licensing cost or software installation. Replica allows you to replicate virtual machines from one Hyper-V host or cluster to another Hyper-V host or cluster. As long as you’re using storage that is supported for Hyper-V, you can use any type of storage for the source and any type of storage on the destination.

Replication frequency ^

One of the limitations in Hyper-V Replica on Windows Server 2012 was the replication frequency. This frequency was hard-coded at 5 minutes and couldn’t be changed. In Server 2012 R2, this is now a configurable setting. When configuring a VM Replica, you can now select 30 seconds, 5 minutes, or 15 minutes for the replication frequency.

Hyper-V Replication Frequency

Hyper-V Replication Frequency

Change Hyper-V Replication Frequency

Change Hyper-V Replication Frequency

In most situations, the default 5 minutes is probably adequate for most workloads. Setting the Replica frequency to 30 seconds would require that you have enough bandwidth to handle the high amounts of data that could potentially be transmitted. In this situation, you’re likely replicating to a nearby building, another area of a data center, or just have a very fast connection to your DR site. 15 minutes would be a better choice for a slower network or servers that provide services or information that won’t require frequent updates (e.g. print servers, static web servers, document/form repositories, etc.)

Recovery Points ^

In Server 2012, Recovery Points were limited to the last 15 hours. In Server 2012 R2, this limit has been increased to 24 hours.

Hyper-V Recovery Points

Hyper-V Recovery Points

By increasing the number of Recovery Points, you can now roll back in time up to 24 hours in the event you find problems related to your need to roll to a DR site.

Extended replication ^

In Server 2012, Hyper-V Replica had the ability to replicate virtual machines from a primary location to a secondary/DR site. In Server 2012 R2, you can now configure extended replication which allows you to replicate to a third site.

Extended Hyper-V Replica

Extended Hyper-V Replica

Here’s an example: Your organization replicates mission critical VMs from your primary data center to a secondary location that is nearby (possibly on the same campus or down the street). VMs can now also be replicated to a third site that is in a different geographic region.

Configuring extended replication is very similar to setting up replication. On your secondary server, right-click the VM and choose Replication then Extend Replication.

Hyper-V Extended Replication

Hyper-V Extended Replication

Configure the replica server that will be receiving the VM and whether to use HTTP or HTTPS. For replication frequency, you can choose either 5 minutes or 15 minutes.

Extended Replication Frequency

Extended Replication Frequency

Linux Replica ^

A new version of Hyper-V wouldn’t be complete without improvements to support for non-Microsoft operating systems. Windows Server 2012 R2 Replica includes improved snapshot support and the ability to use Failover TCP/IP settings for supported Linux distributions.

3 Comments
  1. Steve 7 years ago

    Great article, one question though. Can we replicate from a 2012R2 cluster to a not clustered host?

    Thanks,
    Steve

    • Yes, you can replicate from cluster to cluster, standalone to cluster, cluster to standalone, and standalone to standalone. If you have a Hyper-V cluster, you'll need to install the Hyper-V Replica Broker.

  2. Jerome 7 years ago

    I found a limit at 15 replications, in same time, between 2 hosts.
    Do you know how increase this number ?

    I would like to try to replicate all my VM between my 10 hosts to 1 "backups host".

    Thanks

    Jerome

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