This is an odd one.
I have a mythbuntu system, with a 1 TB HD set up with a JFS filesystem for storing recordings. I feel like I've got most of the problems worked out, except today I have an issue with files disappearing.
Earlier today, I could not access a bunch of my recordings. I checked the mount point for the drive, which is mounted from fstab, and could only see two recording files. I thought this is odd, because I know I watched one of the missing files last night, so I know it got recorded, had the right permissions, etc. I rebooted, and now the strangeness compounds... The files I could not see before are there, and the files that I could see are now missing.
I unmounted the drive and ran fsck, which reported no errors. I don't know exactly what's going on but I'm suspecting some kind of file system corruption. It's working now; shows are being recorded, and I can watch them as well as the older recordings. I can see everything except the two recordings that were visible when I couldn't see any other files.