Backup, Hyper-V, Marketing, and Cluster Shared Volumes

[To get things started on this Hyper-V blog, I’m going to take a few of the Hyper-V posts from the Modern Backup blog and reprise them here. Here’s the second of these.]

Unitrends now supports Hyper-V backup, archiving, and replication at the HOS (Host Operating System) level. This went generally available with our 6.2 release.

One of the things I recently learned is that when someone says they support the backup of Hyper-V, you have to be pretty careful. I think it’s fair for a vendor to note that they protect Hyper-V at the GOS (Guest Operating System) level – in essence, treating each VM (Virtual Machine) as if it were a physical system. But if someone is advertising that they support Hyper-V at the HOS level, you’d expect that they would support it at the hypervisor level so that it was granular to each virtual machine – so that you can protect or not protect virtual machines – rather than having to backup the entire physical machine upon which Hyper-V is executing. I’ve found that this isn’t true in more than a few cases.

You also want to make sure that you are supporting the backup of Hyper-V with some form of CBT (Changed Block Tracking) – so that you’re not doing a master (or full) backup each time but have the ability to support differential and incremental backups. The issue here is that Microsoft’s VSS for Hyper-V only supports master/fulls – so unlike VMware the backup vendor has to add a lot of functionality to get CBT when protecting Hyper-V at the HOS level.

One thing that was particularly interesting that was raised recently by a potential buyer of ours was whether we supported the backup of Hyper-V CSVs (Cluster Shared Volumes.) CSV is a feature of failover clustering that is used in Hyper-V. A CSV is simply a shared NTFS volume among all of the nodes of a Windows failover cluster. We do. But I got a chance to ask the potential buyer why they asked the question – and got an earful of complaints about a few vendors who don’t.

What’s the morale of this story? Be careful of “marketing” claims that backup vendors support Hyper-V backup, archiving, and replication – dig a little deeper – and make sure that your definition of “support” matches their definition.


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