I have a couple VM's running in unraid on my dell r810 server that really don't have the performance I would like or should have. I am thinking that most of this is due to the fact that drive r/w speed outside of a cache drive is slowed considerably in unraid. So what I am wondering is if I can setup my V/M's on a separate ssd outside of the raid (yes I know it isn't a "raid" in unraid but that is the best way to describe what I'm saying) to get better read/write speed. Preferably I would like to get r/w speeds the same or close to if I had windows installed natively. Is my best option to allow the vm to write to the cache drive? Or to set the drive up as an unassigned device and use a plugin to backup the vm? If it is better to use the cache drive would I move the entire vdisk to the cache drive?

I don't see any real speed degradation to the cache drives.  Note that if you're using vdisks, then naturally there's going to be a slow down due to overhead etc.

 

Additionally, most people don't set up their VMs to have the vdisks stay "sparse", which has the ultimate result that trim isn't going to work on the vdisk which will cause a large hit on write speeds

 

But to directly answer the question, if there are concurrent r/w happen to where you have the vdisks currently stored then of course their will be a hit and separating them to a separate cache pool (preferred over using an Unassigned Disk) will remove that.

 

If a perfect world, passing through the entire disk to the VM will always give you the best results