Hi,
A backup is made with the purpose of being able to restore data if something goes wrong. Seen from that point of view it is a very bad habit to have your backups close to the machine(s) or even in the same room.
Mount the drive, make the backup, unmount the drive and store the drive in a safe place (preferably off-site, or in a fire proof/resistant safe). Also check on a regular base if the backup you made can be restored.
A few horror scenario's I've encountered:
- Fire in one of the computer rooms: Tape unit and tapes also burned, they were in the same room.
- Unable to restore crashed system: Backups were in a different room, but on top and next to a (crt) monitor, which made them useless over time.
All this does depend a bit on the importance of the data, but I hope you get the point
Hope this helps.