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The Hyper-V replication feature is intended to create a nearly current copy of virtual machines. This replica is within five minutes of being current in Windows Server 2012 and can be within 30 seconds of being current in Windows Server 2012 R2. In addition to providing a nearly up to date copy of virtual machines, a replica server can also provide point-in-time roll back capabilities through the use of recovery points.
The problem with using Hyper-V replicas as a disaster recovery solution is that there is no interface for restoring files, folders, applications, etc. Sure, you can launch a replica VM and extract the data that you need, but it's a manual process. Furthermore, if data is accidentally overwritten on a VM then the overwrite operation will also be sent to the replica.
Like the Hyper-V Replica feature, vSphere Replication is a feature that is used for creating virtual machine replicas. There are two main situations in which you would want to use a third-party backup solution for DR.
First, you would want to use a third-party backup solution if you required granular recovery capabilities for virtual machine contents. Second, you would likely need a third-party backup solution if you need to back up a lot of virtual machines. The vCenter Server management interface has a 500 VM limit for replication.