So after getting my new unRAID server setup and all my data from various drives transferred over and neatly organized, I have to say that I am loving using unRAID so far! So much so that I still have 20 days left in my trial and already purchased a Pro license. 

 

However, I'm starting to think I don't have things setup optimally here.

 

I've got a 15TB drive array (all 3TB drives, two parity drives) as well as a 500GB SSD currently being used as my cache drive. I have manually set the appdata, domains, and isos shares to: Use Cache Drive > Only, in an effort to force that data onto my SSD. Docker Apps + VM's seem to honor that.

 

However, since this SSD is a cache drive and is outside of the array - if it dies wouldn't I lose all the data on it? In which case I'd have to reconfigure all my VM's and Docker apps? That's certainly not ideal...

 

I'm thinking, is there any way to have that SSD be part of the rest of the array, but still force those shares (and only those shares) to use the SSD for better performance & to not have to spin up other disks (for things like loading Plex meta files, etc)? Basically to have all my VM's and Docker Apps run off an SSD that is protected by parity? I think that would be the ideal scenario for me - would there be any major performance considerations with doing this?

 

Additionally, I have a spare 120GB SSD that I could then setup as a cache drive solely for faster transfer speeds.

 

I believe that was the intended problem to solve with a cache pool (as added in Unraid 6). Or is that not what you're looking for?

Yes, use cache pool, you can have your VMs on the array but write performance will suffer a lot, even if they are on an SSD because all writes are limited by the parity disk.

Yeah, go get another 500GB SSD and add it to the cache pool, implementing BTRFS RAID-1.