I am running Unraid 7.1.2. Every few days the docker service crashes. I am getting BTRFS errors from my cache drive in the log. I have deleted the docker.img file but that has not resolved the problem. It is image file is 50GB so I have not attempted to make it any larger. I ran the "Check Filesystem Status" on the cache drive and it found errors, so I ran it in repair mode. The errors were repaired and the system rebooted fine. But after several days the docker service crashed again. 

 

The cache drive is a 6yo Samsung EVO 870 1TB SSD. If these errors are a sign that the drive is dying then I will replace it. Thanks!

phil-diagnostics-20250520-0847.zip

Edited May 20, 20251 yr by rhodo

Btrfs is detecting data corruption on the pool, suggest running memtest, then scrub the pool and post the result.

Memtest found a ton of errors. I am ordering new ram. When I went to scrub the cache drive I find that it is now listed as unmountable. Any way to recover it?

Updated diagnostics attached. Thanks for your help.

phil-diagnostics-20250520-1257.zip

If the RAM is confirmed bad, don't try to do anything else, or it can cause more damage, wait for the new RAM, and we can then try again.

I have added new RAM, booted into Unraid and started the array. The cache drive is listed as "Unmountable: Wrong or no filesystem".

Please let me know what would be the next steps to get thing up and running again. Thanks.

Post new diags after array start.

Diagnostics attached. Appreciate your assistance with this.

phil-diagnostics-20250522-1336.zip

Type btrfs rescue zero-log /dev/sdf1, then restart the array and post new diags.

Awesome! This brought my cache drive back. Is it now safe to recreate my dockers and VMs?

I tried to recreate my Plex docker while the RAM was still corrupt, so that may be a goner. I understand I may need to reinstall Plex from scratch. I am hoping I can do a reinstall of the other dockers and preserve the data I had. Can the VMs be recovered? I had snapshots. If not, no biggie.

Thanks again!!!

phil-diagnostics-20250522-1352.zip

Click the pool, then "Scrub" and when done post the results from the GUI.

Scrub ended without errors:

UUID:             f296ff39-0784-48e7-a757-99d0ffd864d2
Scrub started:    Thu May 22 14:05:55 2025
Status:           finished
Duration:         0:13:04
Total to scrub:   387.43GiB
Rate:             506.03MiB/s
Error summary:    
no errors found

I noticed that the Docker service has failed to start. Found this in the syslog:

May 22 15:13:01 phil root: mount: /var/lib/docker: can't read superblock on /dev/loop2.

May 22 15:13:01 phil root: dmesg(1) may have more information after failed mount system call.

May 22 15:13:01 phil root: mount error

May 22 15:13:01 phil kernel: BTRFS error (device loop2): open_ctree failed: -5

phil-diagnostics-20250522-1513.zip

Edited May 22, 20251 yr by rhodo
Docker service failed to start

Using the GUI, I deleted the docker.img from the Docker settings and the libvirt.img from VM settings. That resulted in the Docker service starting. I was then able to restore the dockers from Apps > Previous Apps.

I have not yet rebooted to see if the BTRFS errors are still showing up, but I have my dockers back, so, at least for now, I'm happy.

Recommend resetting the pool stats and keep monitoring for any new errors:

https://forums.unraid.net/topic/46802-faq-for-unraid-v6/page/2/#findComment-700582

Posting this here in case it might help someone. After getting my dockers back up I noticed that Plex refused to play several random video files through my Roku that played fine through the Plex web interface. Nothing seemed to help and there did not seem to be any pattern as to which files were affected. I even replaced the affected video files with fresh copies and they still didn't play through the Roku. All I got was the dreaded "Playback Error: Playback has stopped due to multiple playback errors. Please check your connection and try again". Out of desperation I consulted ChatGTP which came up with the below solution.

The codec files in the Plex "Library/Application Support/Plex Media Server/Codecs" folder (located on the Unraid cache pool) may have been corrupted during the cache pool failure that I suffered. Recovering my cache pool and Plex docker did not detect/replace the corrupt codec files. After (1) stopping the Plex docker, (2) deleting all files in the Codec folder, and (3) restarting Plex (which automatically downloaded fresh codecs) everything worked normally again.