I am upgrading my rig with a mother board with 3 M.2 slots.  I would like to use the first one as write cache and RAID 1 the other two in the BIOS on the mother board.  Would like to mount the RAID 1 volume as an unmanaged btrfs volume and store VMs on it, is this possible?  All three M.2 are 240G.

 

Reasoning for using an different RAID type for VMs

1. Writing parity to a spinning disk for a fielsystem hosted on a M.2 NVME will slow the VM
2. This provides redundancy to high write VMs
3. Keeps high write VMs from affecting access to shared storage (SMB, running dockers, ...)
4. M.2 NVME are expensive compared to traditional HDDs and SSDs
5. M.2 NVME are usually have smaller capacities 

 

 

Please provide other ideas if the above is not supported. 

18 minutes ago, CoyoteRay said:

and RAID 1 the other two in the BIOS on the mother board.

This won't work, but you can create an unassigned raid1 pool:

https://forums.unraid.net/topic/46802-faq-for-unraid-v6/?do=findComment&comment=462135

 

Perfect, thank you.