For maximum safety, you should always have one backup disk that is up to date and one that is safely off site. To meet these requirements, you need three backup disks, which you rotate, like this:

1. Connect Drives A and B.
2. When A and B are both up to date, keep B, store A, then connect C.
3. When B and C are both up to date, keep C, store B, then connect A.
4. When C and A are both up to date, keep A, store C, then connect B.
5. Go to step 2.

Is up-to-date backup data really critical? You could use an additional disk to ensure that there are always at least two disks online at any given moment (mirrored).

Is it far to the off-site location? You could use an additional disk to ensure that at least one is safely at the off site location while another is in transit.

Back to the backups page.

---

http://Yost.com/computers/backup-server/additional-disks.html - this page
2007-12-07 Created