i have a DB backup
and i'm using you track (YouTrack 4.1.1 (build #5678 [23-Nov-2012 15:39])
we restared the server where youtrack is installed and then we lost all accounts (failure login)
lucky for me we have all the DB backups (over 40 GB)
now i don't know how to restore any of these db files to the running version.