Virtualized Storage for other VMs on ESXi host

Question

This question is two fold.

Part 1:

Is it a bad idea to virtualize a storage solution and run VMDKs off of that as opposed to the original VMFS datastore.

Essentially lets assume I have 2 TB worth of RAID'd DAS. Currently I have a few VMDKs on the DAS VMSFS. What I want to do is remove the VMDKs off the VMFS, allocate a good 1.8-1.9TB for a FreeNAS installation (a big FreeNAS VMDK), and run the other VMDKs off of that via NFS.

I don't have the hardware for a NAS but have a bunch of different shares. This would simplify my management. I understand there is some overhead with another layer of storage abstraction (A virtual ZFS file system over NFS backed by RAID'd DAS formatted as VMFS) but I don't see how it could be too bad. The NAS also has more features than a simple VMFS datastore on DAS.

Part 2:

VMWare frowns on long running snapshots, but what about ZFS snapshots? Is it safe\recomended to run my guest VMDKs (Windows clients, random servers) on ZFS snapshots? This will give me the ability to quickly rollback VMs to earlier states without the implications of long running snapshots directly on the VMFS.

Answer 1

For a lab environment there's nothing wrong with Part 1, other than the time spent rebuilding when it folds in on itself. Not saying it's will happen, just that it can happen (Murphy's Law).

As to Part 2, I'd have to defer to VMWare.

Answer 2

I don't know about part 2 but for part 1:

Actually, both VMware and HP offer products to do this: VMware VSA and HP VSA. (There might be others offering similar solutions but those are the two I know of.) So it's probably not a generally bad idea. However, I don't know if FreeNAS is an officially supported storage solution so you might lack support when there are problems with it. Without support I wouldn't run it in production. But since you want to deploy it in a lab environment you have to decide for yourself if you can do without support.

There might (just might) be a certain impact as described here. (It's about a flash virtualization platform but the basics of kernel module versus virtual appliance should apply to virtual storage appliances, too.) On the other hand, it's possible you won't experience any performance issues.