As long as a file exists on your personal computer or workstation, the backup service will keep a backup of that file. This "most recent" backup is called the ACTIVE copy. If you never erase it from your personal computer or workstation, the backup service never erases the backup copy.
If you erase a copy from your personal computer or workstation, then the next time you run a backup, the backup copy will be changed from ACTIVE to INACTIVE. It will then remain on tape for 60 days before the backup service deletes the backup copy. This gives you some leeway to recover a file that was lost.
If you modify a file, the network backup service will keep 1 "active" copy and no more than 6 "inactive" copies. The active copy sticks around forever (unless you erase the original file from your personal computer or workstation). The 6 most recent "inactive" copies are kept, each for as long as 28 days.
Each time you change the active file, the previous backup copy in the network backup service is marked as "inactive". If you already have 6 inactive copies is this file, the oldest inactive copy will be deleted to make room for it.
June 13, 2013