hello all ;

    The server has been running stably for 5 years, and we've never encountered such an issue before.

     Last year, we installed a caching hard drive, model = Crucial1t CT1000MX500SSD1.  Occasionally during operation, there were errors reported indicating some value errors, but they would quickly return to normal afterward. Recently, we found that Docker couldn't be updated , with the error message - --》 "Error: failed to register layer: Failed to create btrfs snapshot: input/output error". My Docker is hosted on the SSD caching hard drive, and even restarting the server couldn't resolve the issue.

    after that error， I also found error  on log  :

    

Apr 15 14:52:15 Tower kernel: loop: Write error at byte offset 1317928960, length 4096.
Apr 15 14:52:15 Tower kernel: I/O error, dev loop2, sector 2574080 op 0x1:(WRITE) flags 0x1800 phys_seg 4 prio class 2
Apr 15 14:52:15 Tower kernel: BTRFS error (device loop2): bdev /dev/loop2 errs: wr 1, rd 0, flush 0, corrupt 0, gen 0
Apr 15 14:52:15 Tower kernel: loop: Write error at byte offset 1317994496, length 4096.
Apr 15 14:52:15 Tower kernel: I/O error, dev loop2, sector 2574208 op 0x1:(WRITE) flags 0x1800 phys_seg 4 prio class 2
Apr 15 14:52:15 Tower kernel: BTRFS error (device loop2): bdev /dev/loop2 errs: wr 2, rd 0, flush 0, corrupt 0, gen 0
Apr 15 14:52:15 Tower kernel: loop: Write error at byte offset 1318027264, length 4096.
Apr 15 14:52:15 Tower kernel: I/O error, dev loop2, sector 2574272 op 0x1:(WRITE) flags 0x1800 phys_seg 4 prio class 2
Apr 15 14:52:15 Tower kernel: BTRFS error (device loop2): bdev /dev/loop2 errs: wr 3, rd 0, flush 0, corrupt 0, gen 0
Apr 15 14:52:15 Tower kernel: BTRFS: error (device loop2) in btrfs_commit_transaction:2494: errno=-5 IO failure (Error while writing out transaction)
Apr 15 14:52:15 Tower kernel: BTRFS info (device loop2: state E): forced readonly
Apr 15 14:52:15 Tower kernel: BTRFS warning (device loop2: state E): Skipping commit of aborted transaction.
Apr 15 14:52:15 Tower kernel: BTRFS: error (device loop2: state EA) in cleanup_transaction:1992: errno=-5 IO failure

 

the docker also can't start .

  after the reboot the malfunction persisted.。

what can I do now ?

 

 

Looks like there's not enough space, please post the diagnostics.

Can't see if the docker image is on the pool or disk1, since share system exists on both, still both should have enough space, try recreating the docker image:

 

https://docs.unraid.net/unraid-os/manual/docker-management/#re-create-the-docker-image-file

Also see below if you have any custom docker networks:

https://docs.unraid.net/unraid-os/manual/docker-management/#docker-custom-networks

I followed your method and now everything is back to normal. Thank you.