I already have a SSD as a cache drive. I am adding a NVME M2 device for additional space mainly for VMs but maybe some other things as well. What is the best way to mount this as a cache drive or as an unmounted device. What are the advantages/disadvantages of each

 

 

From what I have gathered, the cache drive typically is used for disk file ingestion, docker apps, and VMs in unRAID.

 

And for me - based on what I know of unRAID, the NVME should just show up as just another device that you will need to pre-clear and format as is the standard practice for unRAID. Depending on how it is installed, you can use it as the second cache device, but if you already have a decent sized SSD, then you might want to instead mount it with the unassigned devices app - and have it just be for VMs. Then when you build your VMs, just to point to that unassigned drive/device instead of the cache drive - and as the "boot drive" when building the VM.  The advantage of this approach should be that you won't be competing with cache bandwidth on the SSD cache drive or with other docker apps. Plus your VMs will likely have the fastest seek times of any device on the system. I have my VMs on another (fast HDD) drive in my array, and it's still pretty fast.

 

About the only disadvantage of it that I can think of would be the VMs wouldn't be covered under the Parity drive, and you might want to back them up on the drive array from time to time - just in case you lose the NVME. Well, that and your cache SSD drive is likely slightly slower than the NVME M2 drive, right? But unless you're talking a large NVME (>1TB) and you're working with moving large files (videos, digital photography, or scientific files) then you're not going to notice that much difference.