I was trying to update a docker and got a read-only file system error.

 

On reading around it seems like it might be cache disk error. I am running a two disk btrfs pool as my cache disk, but don't know enough to see whether there is anything significant in the attached diagnostics. I did notice that on my Dashboard Memory log was at 100%.

 

I'm running 6.8.1. Can anyone help?

 

(I subsequently rebooted the server and am now able to update the docker, but would still like to know if there's any preventative maintenance I should be doing.)

tower-diagnostics-20200310-1448.zip

Your cache pool is completely full, you need to free up some space, then recreate the docker image.

Thanks for looking at this. I'm trying to understand how docker.img works in the cache pool. In my case, docker.img sits inside /mnt/cache and is set to 20GB. So if I free up space by deleting some files in /mnt/cache, and also delete some containers to free up space in the docker image, would I then still have to recreate the docker image?

 

 

You need to delete/move data from the cache pool, deleting docker containers won't do much for this, and the docker image will always need to be recreate since current one is corrupt, likely from running out of space, recreating the image is very easy.

Thanks for the help. All done. Recreating the image was so much easier than I expected. I was worried because I had two instances of some dockers (named them differently of course), and was pleasantly surprised to see both listed in the previously installed apps list. Also took the opportunity to turn on log rotation.