Can you mix vSAN and SAN assigned disks on the same VM

[Brainbugg]

Hi There

I'm constantly being asked interesting questions by our architects so I thought I would ask the advice of the community.

Can you install an HBA in only one node of a 2-node vSAN cluster and then build a vm that will be used as a backup server on the vSAN datastore but then also assign an additional SAN assigned disk to this vm which the backup server will  use to backup to?

I know this doesn’t make sense at all. My view is no this shouldn't be done for various reasons but mainly from a vSAN architecture point of view ie vSAN is object based storage which uses Storage policies so here immediately there is a problem because you will combining both vSAN and non vSAN datastores on a single vm.

Unless you can assign 2 different policies per disk ie raid 1 to the OS disk and a Zero redundancy policy to the SAN assigned disk.

Still this is a recipe for disaster and I would like know your your opinions so that I can go back to them with facts.

Thanks

[TheBobkin]

Just in case you/they were suggesting to use the same controller for both functions, don't mix vSAN and VMFS used for vmdks etc. on the same controller:

VMware Knowledge Base

The VMFS vmdk wouldn't be stored on vSAN and thus wouldn't be an Object and thus vSAN wouldn't really care about it - sure it would show as <shrug> under VM > Monitor > Policies > Hard Disk, but other than that I can't see anything about it being particularly broken.

That being said (and of which you seem to be abundantly aware) having multiple storage types as dependencies for a single VM to function isn't a great idea - I am not an expert in backup solutions but it seems like most of our customers use methods that collect the backup data locally on vSAN and then move it somewhere else (though not necessarily via all just one VM with multiple storage types attached).

To answer your other question - yes you can apply whatever you want varying Storage Policy to each individual disk on the same VM, and technically it is feasible to do things even beyond this like making a snapshot chain with each snapshot having different Storage Policy than its parent :smileycool:

Bob