Unfortunately, tmpfs volumes lose their content when the container is stopped. See: https://docs.docker.com/storage/tmpfs/. The volume is still there, but it is empty.
Thanks @Ereski, the question is based that we noticed that when we run out of space in Balena, the device started to malfunction… To be more precise, the resin-supervisor container was not starting until we deleted all the data from one of the volumes. We are planning to use that volume for video recordings and we need to use as much space as we can.
Thanks for letting us know! And is there a reason why the resin-supervisor container will not start when running out of space? Is there a disk usage threshold for the resin-supervisor not start?
I am not familiar with the details of the supervisor, so I cannot give you a definitive answer. The supervisor also runs as a container, and the engine definitely needs some extra space while running.
We don’t currently have a recommended minimum of disk space that should be free, but it shouldn’t be much for normal operations.
I know I’m answering an old post but I have seen the same behavior as described above. Supervisor container not starting because of filled storage. This was with more recent versions of the host OS and supervisor.
Is there any way of preventing this problem yet? Or is your advise still to monitor it myself and preserve space this way?
Yes at the moment we recommend monitoring the system resources yourself. Currently we don’t have any meaningful actions that we can take automatically that will guarantee a reliable system state if we detect filled storage. I realize it’s probably not the answer you wanted to hear, but we’re open to suggestions, if you have any.