Ok, solution is here and is simple. My Container Station install directory is /share/CACHEDEV1_DATA/.qpkg/container-station, I'm referring to it below as [INSTALL_DIR].
1. Edit [INSTALL_DIR]/script/run-docker.sh. It's the core of the solution and is absolutely safe to comment out the line (with '#'):
2. Edit [INSTALL_DIR]/etc/supervisord.conf. Again safely disable debug in section [program:qbus]. If you have there 'environment=QBUS_DEBUG=1', set it to
3. Additionally you can optimize the save
according to comments inside the file. I'm not really sure how far you can get in this optimization. I tried to disable "save" whatsover and then Container Station doesn't write to disk unless really needed by the containers. This setting probably impacts the behaviour of the Container Station, I guess mainly it's web interface.
All of the mentioned parameters cause the app to periodically write to disk, even without any activity inside the containers. First part of the solution is a result of communication with Qnap helpdesk. Absolutely awful: in about 2 months of lifetime of my ticker they twice requested a remote access session just to tell me (upon second reminder) that Container Station simply doesn't support disk spindown by design. I begged them to advice how to simply avoid the ** useless debug mode. Ok, here it is.