Comment # 6 on bug 1175637 from Wolfgang Bauer

(In reply to Fabian Vogt from comment #5)
> Ok, so they should not actually be unreferenced.
They may be if the cached entries are purged from the database (which is just a
cache), but the referenced files in file_db_data were not/could not be deleted
for some reason.

Just a thought: maybe akonadictl fsck cannot rename/move the files because they
are actually still in use by some process?
And maybe akonadi itself fails to delete them in the first place when it
removes entries from the cache for the same reason? (resulting in those
unreferenced files to exist)
I suppose the strace should show if that's the case...