2 x NAS 14TB and 1 x 512 GB NVMe for VMs and cache [SOLVED]

[theunraidhomeuser]

Hi everyone, first post, please be nice 🙂

I am just setting up UNRAID and was wondering if I did this correctly per the attached. I don't need parity as critical data will be rsync'ed to an offsite every night.

 

• 2 x 14TB mounted as normal array devices
• 1 x 512 GB NVMe mounted as cache

 

Needless to say, I don't want to waste 512 GB NVMe just for caching the hard drives, I'd like to run a couple of Windows and Linux VMS off it.

 

• Q1: per the attached screenshot, is it correct to assign the "domains" share to "Use Cache: ONLY"?
• Q2: who or what defines how much space on the NVMe is used for caching the NAS hard drives vs space allocated to VMs? I don't think I'll run into any trouble here in terms of space, just want to understand. I would have expected some sort of "max space allocated to caching". Do I need to set up different partitions for that? i.e. a partition for normal caching and another partition for the VMs?

 

Thanks!

 

Edited April 25, 2020 by theunraidhomeuser

[itimpi]

Q1)  Using Only is fine as long as you do not already have files in that share on the array.   If you DO have files on the array then set it to Prefer; disable the VM service and Docker services under Settings; run mover to get the files moved to the cache; re-enable the Docker and VM services; (optional) change the Use Cache setting to Only.

Q2) There is no way to explicitly set the division between VM and file caching.  What you can set is the Minimum Free Space setting under Settings >> Global Share settings and when free space on the cache falls below this then files get written directly to the array.  The recommended value is to be larger than the size of the largest file you are likely to write.  Having said that since you do not have a parity drive (which is what limits speed writing to array drives) I wonder if you even need to bother caching file writes in the first place.

 

[trurl]

Also note that caching user share writes doesn't happen unless you make it happen. Each user share has settings including whether and how it uses cache.

 

In addition to domains share being on cache, your appdata and system shares will be (and should be) on cache by default.

[theunraidhomeuser]

thanks both, that's exactly the info I needed!