I keep all my dockers /config on appdata cache-only share and it works fine in most cases.

 

As cache disk capacity is rather limited is it safe to symlink some of the subdirectories of /config to array share for storing larger amounts of data?

 

Example: JDownloader docker uses /config/Downloads for storing downloaded content. In some cases downloads can take lots of cache space. I'd like to symlink /config/Downloads (in fact /mnt/user/appdata/jdownloader/Downloads/) so it points to /mnt/user/<array sharename>/<dir>. Effectively JD config files would stay on cache, but downloaded content would be sent straight to disk array.

Is it safe/effective way to handle the problem?

None of the docker veterans know how to do it?

 

I experimented with symlinks and they are totally ignored by docker.

 

I also tried to mount a directory with option bind (mount --bind /<array share>/<dir> /<cache disk/<dir>) and it seems to work i.e. such directory is visible for docker. One thing to note is that you probably should not bind two user shares like so:

/mnt/user/download/jdownloader on /mnt/user/appdata/jdownloader/mydownloads type none (rw,bind)

(Binding two user shares produces strange results)

 

but direct reference to cache works

/mnt/user/download/jdownloader on /mnt/cache/appdata/jdownloader/mydownloads type none (rw,bind)

 

command:

mount -o bind /mnt/user/download/jdownloader/ /mnt/cache/appdata/jdownloader/mydownloads/

 

So far the above seems to work (also mover behaves correctly as /mnt/user/download utilizes cache)

 

Any comments?