- Solved
- Minor
The Issue: Creating a ZFS formatted cache pool with two disks mirrored was not possible. Following the standard steps of setting up the pool, assigning two disks, and formatting them resulted in the format failing. The format fails as the disks remain unmounted and Unraid suggests to format them, despite just pressing the format button. This was very consistent - attempt multiple times, preclear the disks and try again, fails. Delete the pool and reset it up, try again, same failure. Restart the server, try again, same failure. Stop array, repeat, fail, etc.
Resolution: Follow the same steps but instead as a btrfs cache with the same two disks, or a ZFS pool with RAID0 with the same disks resolved the issue. No changes in hardware or additional steps required to find immediate success.
I ended up going with ZFS RAID0, but I tested with success with btrfs before switching to ZFS RAID0 and sticking with it.
Additional Troubleshooting Steps Taken: Preclearing the disks, erasing them, deleting partitions, stopping the array a few times, restarting the server, repeating the same steps.
This is the logs from the process of trying to setup the zfs mirror pool and it failing.
QuoteJun 18 17:53:10 Dane emhttpd: creating volume: cache (zfs)
Jun 18 17:53:10 Dane emhttpd: cache: invalid profile: 'mirror' 2 0
Jun 18 17:53:10 Dane emhttpd: mounting /mnt/cache
Jun 18 17:53:10 Dane emhttpd: shcmd (1201): mkdir -p /mnt/cache
Jun 18 17:53:10 Dane emhttpd: /usr/sbin/zpool import -d /dev/sdc1 2>&1
Jun 18 17:53:10 Dane emhttpd: no pools available to import
Jun 18 17:53:10 Dane emhttpd: cache: no uuid
Jun 18 17:53:10 Dane emhttpd: /mnt/cache mount error: Unsupported or no file system
Jun 18 17:53:10 Dane emhttpd: shcmd (1202): rmdir /mnt/cache
It appears the process fails with the invalid profile, and from there the subsequent steps don't work. After clicking the format button I would see it say "Formatting..." on the Main tab for a moment, before returning to the cache disks being unmountable and Unraid suggests I need to format them. I rinsed and repeated this without any success before discovering the solution was to...just don't use zfs mirror.