When configuring the rockon service by selecting a share (share_a) and then starting the service, several folders and subvolumes are created.
If the rockon service is later reconfigured to use a different share (share_b) a new set of folders and subvolumes are created in share_b, but what was created in share_a is not cleaned up.
This manifests as an operational issue if you then want to delete share_a. It is not possible to delete share_a when it contains subvolumes. To delete share_a it is necessary as of the time of this post to first bring up the command line and enter
btrfs sub delete /mnt2/share_a/btrfs/subvolumes/*
In the process of working through this I have also found that you can have a situation where you have a share configured for the rockon service with the rockon service started and running. Then install the transmission rockon, and then the 1st step of the rockon configuration (selecting the share for downloads) is skipped. If you complete the process and then go back and edit the rockon configuration, you just see 4 configuration items (port, port, custom, custom) and the 2 ‘share’ configurables are missing. I also checked and saw the same behavior for the OpenVPN rockon so I assume this would affect all of them.
Unfortunately I’m not sure how to exactly reproduce the circumstances that cause this. If you think this might be in the logs somewhere I can email them.