Top 10 features for IT pros
in Windows Server 2012 (R2)
that seem to be unknown or unloved
by Mike Resseler
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Feature 4: Hyper-V Replication

Chapter 4

Replication is a great add-on in your disaster recovery strategy. It is certainly not a backup replacement but complements backup in your strategy. And as with everything else, this is a feature within the operating system. Hyper-V Replica is storage agnostic, application agnostic and is asynchronous.

But please note that Hyper-V Replica has its limitations:

  • It is asynchronous
  • It is capable of scheduling replication only every 30 seconds, 5 or 15 minutes but you can perform extended replication
  • There is a limit of 24 additional recovery points, which must be within the same day
  • It only works with VMs that run on Windows Server 2012 or 2012 R2
  • It works with a log file putting additional writes on your primary server and additional load on your replica server

However, if no alternative is available for replication, this feature is very welcome in your environment.


If you already have installed the Hyper-V role on your hosts (both on the primary and replica server), then you can enable a Hyper-V host as a replica server. Note that you can replicate VMs from the primary server, which then can become a replica server for other VMs and vice versa. Communication happens over an IP-enabled network and can be done over Kerberos authentication (default port 80) or certificate-based authentication (default port 443) if you are not in the same domain or you want to enable encryption on the sent data. Right-click on the host that will be serving as a replica and choose Hyper-V settings. Then go to Replication configuration and configure your settings (see Figure 6).

Figure 6: Enabling a replica server

Figure 6: Enabling a replica server

After that, and whenever the necessary changes are made to the firewall, you can enable replication per VM by right-clicking on that VM and choosing Enable Replication (see Figure 7).

Figure 7: Replicating a VM wizard

Figure 7: Replicating a VM wizard

After the initial replication (which might need to be planned because of the heavy workload), only the delta changes will be transferred according to your selected time interval.

Now you can perform an actual failover (worst case), a planned failover or a test failover.

Note that a planned failover demands downtime but has no data loss, while an actual failover can have data loss and also has downtime. A test failover creates a copy of your VM and allows you to do some tests, certainly if you implement an alternative network configuration for that VM so it doesn’t interfere in your production environment.

More information can be found here:

Mike Resseler
About the author
Mike Resseler is a Product Strategy Specialist for Veeam. Mike is focused on technologies around Hyper-V and System Center. With years of experience in the field, he presents on many occasions at large events such as MMS, TechEd and TechDays. Mike has been awarded the MVP for System Center Cloud and Datacenter Management since 2010. His major hobby is discussing and developing solid disaster recovery scenarios. Additionally, he has enterprise-class experience in private cloud architecture and deployment, with marked focus on protection from the bottom to the top. He holds certifications in many Microsoft Technologies such as MCITP.