Cache Unmountable: No file system

[fernandoaleman]

Hello all. I am currently running Unraid 6.11.5 and have a cache pool of 2 devices in btrfs with 2 nvme drives. I was wanting to remove 1 of the nvme drives so I stopped the array, set the nvme cache drive that I wanted to remove to "no device" (which then moved it to the Unassigned Devices, then checked the box stating "Start will remove the missing cache disk and then bring the array on-line" and started the array.  Now, next to my single cache nvme drive it says "Unmountable: No file system". I do see an option under Array Operation Format that says "Unmountable disk present Cache" and the option to check "Format will create a file system in all Unmountable disks". If I do this, should this bring my cache file system back up? I have attached my Diagnostics just in case.

paco-diagnostics-20230423-1012.zip

[JorgeB]

35 minutes ago, fernandoaleman said:

If I do this, should this bring my cache file system back up?

No, it will delete all data.

 

According to this the pool wasn't redundant:

Apr 23 10:01:50 Paco kernel: BTRFS warning (device nvme1n1p1): chunk 85963309056 missing 1 devices, max tolerance is 0 for writable mount

 

So you could not remove a device, type:

btrfs-select-super -s 1 /dev/nvme0n1p1

 

Then stop array, unassign all cache devices, start array, stop array, re-assign both cache devices, start array, post new diags

 

[fernandoaleman]

@JorgeB Thanks so much! I followed your directions and that seems to have fixed it. My cache pool is now back and all my files are accessible. I have attached the Diagnostics again in case you would like to confirm. What would be the proper way to remove 1 of the 2 nvme drives from the cache pool? Just want to make sure this doesn't happen again. Much appreciated. 👍 

paco-diagnostics-20230423-1100.zip

Edited April 23, 2023 by fernandoaleman

[JorgeB]

Your pool is mostly using the single profile for data, convert to raid1, check that it actually converted and data is all raid1, then you can remove a device.

 

                  Data      Metadata  System                              
Id Path           single    RAID1     RAID1    Unallocated Total     Slack
-- -------------- --------- --------- -------- ----------- --------- -----
 1 /dev/nvme1n1p1         -   2.00GiB 32.00MiB   463.73GiB 465.76GiB     -
 2 /dev/nvme0n1p1 222.00GiB   2.00GiB 32.00MiB   707.48GiB 931.51GiB     -
-- -------------- --------- --------- -------- ----------- --------- -----
   Total          222.00GiB   2.00GiB 32.00MiB     1.14TiB   1.36TiB 0.00B
   Used           190.15GiB 544.02MiB 48.00KiB 

 

[fernandoaleman]

@JorgeB I will follow your instructions to Raid1 so I can remove that additional drive. Again, thanks so much for the help. You saved my day! 🙏