Paul Gregory | 18 July 2012
Having discussed shared nothing Live Migration on Monday today is the turn of Hyper-V Replica, a disaster recovery service inbox with Hyper-V 3.0
The Hyper-V Replica feature allows a copy of a virtual machine to be frequently updated with an 'off' copy of the virtual machine. This enables in a disaster scenario a copy of the virtual machine could be brought online very quickly with little data loss. This could be used for keeping virtual machines in sync in the following situations:
- A live site and a DR site
- Head office/data centre and a branch office
- Data centre and a hosting provider
The replica is updated between every 5-15 minutes based on the time it took to complete the last synchronisation. In addition 'previous' versions of the computer can be kept. During the setup an administrator can define the number of previous versions to be kept and then Hyper-V will then automatically take a snapshot of the virtual machine at 1 hour intervals to maintain the number of copies requested. For example if the administrator selects 3 copies the replica virtual machine would have snapshots going back 3 hours (1 per hour). When snapshot 4 is taken the first one would be deleted therefore maintaining the 3 hours of rollback capability. As an advanced option if the virtual machine contains applications that are VSS aware Hyper-V will also notify the VM that a snapshot is being taken allowing the applications to ensure all their data is crash consistent.