I have two cache arrays, one is effectively a write cache for the array, and is striped, the other is where my appdata sits, and is mirrored.

 

I'm getting a lot of errors filling up syslog from the appdata cache:

 

BTRFS warning (device sdb1): lost page write due to IO error on /dev/sdc1 (-5)
BTRFS error (device sdb1): error writing primary super block to device 2

 

I can see these errors from the btrfs command too:

 

root@Tacgnol-Core:/var/log# btrfs dev stats /mnt/appdatacache/
[/dev/sdb1].write_io_errs    0
[/dev/sdb1].read_io_errs     0
[/dev/sdb1].flush_io_errs    0
[/dev/sdb1].corruption_errs  0
[/dev/sdb1].generation_errs  0
[/dev/sdc1].write_io_errs    21657204
[/dev/sdc1].read_io_errs     4497345
[/dev/sdc1].flush_io_errs    1108503
[/dev/sdc1].corruption_errs  0
[/dev/sdc1].generation_errs  0

 

The other array is fine.

 

These two SSDs are relatively new, and I suspect it's a cable issue, which is nice and easy to replace, but how do I tell it to "rebuild" the array or whatever it is going to need to do?

 

Data, RAID1: total=313.00GiB, used=213.75GiB
System, RAID1: total=32.00MiB, used=80.00KiB
Metadata, RAID1: total=2.00GiB, used=1.67GiB
GlobalReserve, single: total=387.48MiB, used=0.00B

 

Diagnostics attached.

tacgnol-core-diagnostics-20220418-1903.zip

Update: Cache seems to have gone read-only and wont fix itself. Scrub just aborts. What do?

tacgnol-core-diagnostics-20220418-2014.zip

Best bet is to backup that pool and re-format, then see below for how to better monitor pools for errors:

 

https://forums.unraid.net/topic/46802-faq-for-unraid-v6/?do=findComment&comment=700582

 

I ended up pulling the "failed" drive, letting it rebalance to single drive, then putting the failed drive back (with new cable obviously) and rebalancing to raid1 again.

 

I had to rebuild docker.img but everything else seems fine.