I’ve noticed that whenever I cancel a sync operation before it completes, the storage space being reported by iOS becomes unreliable. It’s almost as though the cancelled sync operation does not do any clean up or garbage collection, so the data in limbo just sort of hangs around on the app forever, if that makes any sense. I trust the sync storage space reported by the server as completely authoritative, so whenever the iOS app starts reporting that more storage is being used, I typically refer to the usage reported by the server, and the server has never been wrong so far.
I was syncing a number of items, and after some time, after most items were synced, I ended up cancelling a sync operation of BBC’s Frozen Planet (using the settings: limit 3 episodes / unwatched / medium quality) because it was taking a long time to transcode. Ever since, the amount of storage space reported in use by the iOS app has been larger than the actual amount of storage space in use as reported by the server. I have a screenshot of the iOS storage settings screen, and the Plex Web client iOS device overview.
iOS storage overview:
Plex Web client of storage on that Plex iOS app:
Note that according to iOS’ storage overview screen, the Plex app is occupying 18.3 GB of storage. The server is reporting that the Plex iOS app has 15.8 GB of content synced to the device. That leaves a difference of 2.5 GB.
To make sense of the 2.5 GB difference, let’s say the Plex binary or full install of Plex on the iOS is about 100 MB. That leaves 2.4 GB of storage in use by Plex as reported by iOS itself. Further, let’s say there is another 1.0 GB of caches. That leaves 1.4 GB of unaccounted for storage space that Plex is using as reported by the iOS app, but the actual content of that 1.4 GB is nowhere to be found. This leads me to believe that remaining 1.4 GB of unaccounted for used space is the data in limbo I hypothesized about in the opening paragraph.
Also, I have logs for during the time this happened. It was two days ago, using iOS Plex 4.0.5 and PMS 0.9.12.13.1464-4ccd2ca. The context of the log: it was a fresh iOS Plex install of 4.0.5, so there was no sync content. I then performed multiple sync operations, queuing about 12 artists (multiple albums each), and about 4 TV shows (3 unwatched episodes, medium quality). It should also include the cancellation of the Frozen Planet sync operation. This debug log spans from that time to just a few minutes ago.
It may also be worth reading a similar sync issue I detailed here–again, related to the calculation of sync storage on the iOS Plex app: https://forums.plex.tv/discussion/comment/1037512/#Comment_1037512