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VMware hypervisor swap-out means loss of data storage features

Switching from VMware's hypervisor to a commercial or open source alternative might necessitate third-party tools to replace storage features.

Swapping out a VMware hypervisor for a commercial or open source alternative is certainly feasible these days, but IT users might need to seek out third-party tools if they want similar sorts of data storage features.

Marc Staimer, president and founder of Dragon Slayer Consulting in Beaverton, Ore., said Microsoft's Hyper-V, Citrix's XenServer virtualization platform and the open source Kernel-based Virtual Machine (KVM) hypervisor don't offer the same storage integration capabilities that technologies such as VMware's Storage APIs for Array Integration (VAAI) and vStorage APIs for Storage Awareness (VASA) application programming interfaces (APIs) do.

In this podcast interview with SearchVirtualStorage's Carol Sliwa, Staimer discussed the storage implications of switching from VMware's hypervisor to an alternative technology and provided advice on how to make the transition go smoothly.

VMware has the dominant hypervisor, but there's a lot more competition these days. From the perspective of data storage, how feasible is a switch from VMware's hypervisor to a different hypervisor?

Marc Staimer: From the storage perspective, it's not much of an issue at all. You have to make sure that your storage system from your vendor has been certified and that it works with the new hypervisor. But, generally speaking, if you're moving from [a] VMware [hypervisor] to everyone else, that's not much of an issue. Most of them have self-certification tests the vendors work with. It's about the same issue as moving from one operating system to another. Does it work with that operating system?

The one that will probably have the most requirements would be Microsoft on Hyper-V. You have to make sure your vendor is certified with Hyper-V and specifically [Volume Shadow Copy Service] VSS.

You just mentioned Microsoft. Again from the storage standpoint, which hypervisor might be the easiest to switch to?

Staimer: Well, easy is always a relative term. Let's start with VMware. If you're using a lot of their functions, if you're using the VAAI and VASA APIs, in which you've integrated in and you're used to using it from a VMware administrator, you're not going to get the same kind of integration with KVM, XenServer or Hyper-V. It's a different feel to it from a virtual machine administrator.

If you're using some of the functions like [Site Recovery Manager] SRM, Storage vMotion or [Virtual SAN] vSAN, you're not going to necessarily have that from the hypervisor vendors you're switching to, so you may need third-party software to fill in the gaps. But, from the actual storage perspective, the storage system itself, they're all going to be pretty easy to move to.

You just mentioned a lot of VMware storage features. Would any of them complicate a swap to a different hypervisor; and if so, how?

Staimer: They would [complicate a swap] because if you're used to using them and they don't exist on the new hypervisor, you're going to have to find a third-party equivalent that works on that new hypervisor. If it's something you're dependent on and it doesn't exist with them like, let's say, vSAN, you're going to need a third party like PernixData or ScaleIO from EMC, or a variety of other players who fit in that space that will enable you to get similar capabilities, because as a VMware administrator you're used to it. Now [that] you're going to become a different hypervisor administrator you're going to miss it. So, it just means you're going to have to find a third party to go with it. Most of the hypervisor vendors will have a list of products that will provide equivalent features for them.

What storage steps would an IT user need to take in switching from VMware to a different hypervisor?

Staimer: First, you'd need to set up a pilot to make sure you're comfortable with the issues that will come up in switching from VMware to another hypervisor. You want to make sure it works the way you expect it to, [and] that it has the performance you expect it to have. Does it work on the equivalent of vMotion, Live Migration or whatever the case might be? Does it work the same or can you adapt to it?

For [disaster recovery] DR, does it work in a way that you can adapt to? On the storage management [front], does it work in a way that you can adapt to? You have to actually do it to make sure you're comfortable with it. So, I would definitely set up a pilot to work out the bugs before you put it into production.

Is there any other advice from a storage perspective you would offer to someone considering a hypervisor switch?

Staimer: I'd work with my storage vendor to make sure they're comfortable with the switch, [and] that they've gone through all the tests [and] can assure you [that] here are the things to look for because they will have obviously seen all the differences. They will have already experienced it with other customers or at least in their labs. They can tell you what to expect, and that's going to be very important. So, I would definitely work closely with my storage vendor, storage integrator or storage value-added reseller -- whoever sold you the storage equipment -- to make sure it goes smoothly when you go into production.

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