Hey All!
I have an array of 3 ssd's as a cache because I was told that SSD's should be used as a cache instead of using a normal pool.

I updated my instance, and now it is giving me the error "Unmountable: wrong or no file system", and i cant figure out why!

Crucial data is backed up but it would be nice to have my array working again!

tower-diagnostics-20260702-1107.zip

Post the output from btrfs fi show

root@Tower:~# btrfs fi show

warning, device 3 is missing

Label: none uuid: 5e6be76c-cb26-4771-a977-70d20cc14982

Total devices 3 FS bytes used 1.75TiB

devid 1 size 953.87GiB used 607.00GiB path /dev/nvme0n1p1

devid 2 size 1.86TiB used 610.01GiB path /dev/sdb1

*** Some devices missing

Label: none uuid: 598017b0-28dc-4ed1-96b1-7f8205c3c5f5

Total devices 1 FS bytes used 14.56GiB

devid 1 size 50.00GiB used 24.07GiB path /dev/sda1

root@Tower:~#

Here is what the dashboard look like

Edited July 5Jul 5 by adastorm

Is the missing device expected? Post the output from

blkid /dev/sda

and

fdisk -l /dev/sda

root@Tower:~# blkid /dev/sda

/dev/sda: PTTYPE="dos"

root@Tower:~# fdisk -l /dev/sda

Disk /dev/sda: 1.86 TiB, 2048408248320 bytes, 4000797360 sectors

Disk model: P220 2048GB

Units: sectors of 1 * 512 = 512 bytes

Sector size (logical/physical): 512 bytes / 512 bytes

I/O size (minimum/optimal): 512 bytes / 33553920 bytes

Disklabel type: dos

Disk identifier: 0x00000000

Device Boot Start End Sectors Size Id Type

/dev/sda1 2048 4000797359 4000795312 1.9T 83 Linux

root@Tower:~#

A partition exists; let's see if there's a btrfs signature

blkid /dev/sda1

root@Tower:~# blkid /dev/sda1

/dev/sda1: UUID="5e6be76c-cb26-4771-a977-70d20cc14982" UUID_SUB="d436ca3c-86aa-403c-b8d0-5848e60bc155" BLOCK_SIZE="4096" TYPE="btrfs"

The UUID is the same one from the pool. Temporarily disconnect all other devices, and with just the sda connected, post the output from

btrfs fi show

Just to clairify (im new to the world of storage, im a avl technician) Do you mean to physically disconnect?

Yep, or if you prefer to avoid messing with cables, you can use

echo 1 > /sys/block/sdX/device/delete

echo 1 > /sys/block/nvmeXn1/device/device/remove

The bottom one is for NVMe devices; that will drop them offline, the array should be stopped, a reboot will bring them back.

Im away from the device physically right now, but i first stopped the array but they didnt seem to do anything after:

root@Tower:~# echo 1 > /sys/block/sdX/device/delete

bash: /sys/block/sdX/device/delete: No such file or directory

root@Tower:~# echo 1 > /sys/block/nvmeXn1/device/device/remove

bash: /sys/block/nvmeXn1/device/device/remove: No such file or directory

root@Tower:~#

You need to replace X with the correct devices you want to offline, e.g.,

echo 1 > /sys/block/sdb/device/delete

echo 1 > /sys/block/nvme0n1/device/device/remove

Ok sorry that took a bit:

root@Tower:~# btrfs fi show

Label: none uuid: 598017b0-28dc-4ed1-96b1-7f8205c3c5f5

Total devices 1 FS bytes used 14.56GiB

devid 1 size 50.00GiB used 24.07GiB path /dev/sda1

root@Tower:~#

That contains a different btrfs filesystem, i.e., it's not part of the pool, it does appear to have some data in case you want to try and mount it to check.

thats really strange, because it should be the third drive in my pool. i haven't physically altered my unraid setup at all. Is there any way to recover and start from scratch?

A full recovery seems unlikely to me, since, besides the missing device, the pool has write errors with one other device, and the pool was not fully redundant, possibly because of that:

Jul 2 11:07:25 Tower kernel: BTRFS info (device nvme0n1p1): bdev <missing disk> errs: wr 1873035, rd 89663673, flush 0, corrupt 1, gen 0

Jul 2 11:07:25 Tower kernel: BTRFS info (device nvme0n1p1): bdev /dev/sdb1 errs: wr 58, rd 0, flush 0, corrupt 120, gen 0

Jul 2 11:07:25 Tower kernel: BTRFS warning (device nvme0n1p1): chunk 1104150528 missing 1 devices, max tolerance is 0 for writable mount

Jul 2 11:07:25 Tower kernel: BTRFS warning (device nvme0n1p1): writable mount is not allowed due to too many missing devices

You can try these recovery options here to see if you can save some of the data, but likely the pool will need to be reformatted in the end

https://forums.unraid.net/topic/46802-faq-for-unraid-v6/page/2/#findComment-543490