I have recently tried to install a second Cache drive as a redundancy. However since adding this drive I have had multiple issues crop up one after another.

My initial problem was that the cache pool was giving the error "pool BTRFS too many profiles". Reading a different forum post it stated to run a Scrub and Balance. I have completed both of these but unfortuantly both abort before they have completed

This error seems to have gone away on its own however everytime i start the array i now get a warning error stating "Cache pool BTRFS missing device(s)

SAMSUNG_SSD_830_Series_S0Z4NEAC899525 (sdg)" This is the original drive i had fitted before i installed the second drive.

Also the Docker Service fails to start as the Cache is now in a read only state with the following errors showing in the log

Aug 13 18:10:10 Tower kernel: BTRFS: error (device sdg1 state A) in __btrfs_free_extent:3228: errno=-117 Filesystem corrupted
Aug 13 18:10:10 Tower kernel: BTRFS: error (device sdg1 state EA) in btrfs_run_delayed_refs:2215: errno=-2 No such entry
Aug 13 18:10:10 Tower kernel: I/O error, dev loop2, sector 0 op 0x1:(WRITE) flags 0x800 phys_seg 0 prio class 0
Aug 13 18:10:10 Tower kernel: BTRFS error (device loop2): bdev /dev/loop2 errs: wr 0, rd 0, flush 1, corrupt 1, gen 0
Aug 13 18:10:10 Tower kernel: BTRFS: error (device loop2) in write_all_supers:4044: errno=-5 IO failure (errors while submitting device barriers.)
Aug 13 18:10:10 Tower kernel: BTRFS error (device loop2 state EA): Transaction aborted (error -5)
Aug 13 18:10:10 Tower kernel: BTRFS: error (device loop2 state EA) in btrfs_sync_log:3186: errno=-5 IO failure

I have now tried to remove the second drive by stopping the array, removing the drive however i cannot change the drive pool number from 2 to 1 the option is not there. I did read that you just need to start the array selecting the "Yes" tick box but this just gives an error message stating that there is a wrong pool state

If anyone could please help me with some steps on how to get the array back to a working state with or without the redundancy drive it would be gretly appreciated. I noted that adding a diagnostics file can be helpful so I have attached one.

If there is any other information i can provide to help then please let me know

tower-diagnostics-20250813-1859.zip

You cannot remove a device because the pool profile is not raid1, but Btrfs is detecting data corruption. I suggest running Memtest first, then try to copy what you can from the pool and reformat.