All centrally managed computers are backed up each week night between 8 P.M. and 4 A.M. These nightly backups are incremental backups, i.e., files that have changed since the previous backup. Full backups, i.e., backups of all files, are performed each weekend beginning at about midnight on Saturday.

Incremental tapes are kept for one week, so that a tape used on Monday night will be reused on the following Monday night. Full backup tapes are stored off site for four weeks and then reused.