I think this is what is happening.
You've got mover running every hour.
Because of the logging done by mover, it has very rapidly filled up /var/log. Under settings, Scheduler, mover settings, disable mover logging. If nothing else, it makes for a nicer syslog to read.
Mover keeps attempting to move appdata from the array to the cache drive. All well and good, but it is continually unable to do so completely because you've got docker running. Settings, docker, stop running. Then Main, Array Operation, run mover. After its done, re-enable docker. Now everything should be on the cache drive and mover won't complain as much, and as a bonus you'll see a big speed bump.
Of course, you're going to have to reboot first to accomplish this as with /var/log filled, strange things result.