Ken Blake wrote in
:



Here's my standard post on the subject:

RAID 1 (mirroring) is *not* a backup solution. RAID 1 uses two or
more drives, each a duplicate of the others, to provide redundancy,
not backup. It's used in situations (almost always within
corporations, not in homes) where any downtown can't be tolerated,
because the way it works is that if one drive fails the other takes
over seamlessly.

Although some people thing of RAID 1 as a backup technique, that is
*not* what it is, since it's subject to simultaneous loss of the
original and the mirror to many of the most common dangers threatening
your data--severe power glitches, nearby lightning strikes, virus
attacks, theft of the computer, etc. Most companies that use RAID 1
also have a strong external backup plan in place.

"Why RAID is (usually) a Terrible Idea"
http://www.pugetsystems.com/articles?&id=29

Attachment decoded: untitled-1.txt

I don't use it as a backup per se. I have two external drives I alternate
as backup drives periodically. My thinking is more that the most common
fault I would probably suffer would be a disk failure. If that happens
than the other drive in the pair will still have my data, and I can
quickly run another backup, then fix/replace the failing drive.

Lately I have been reconsidering that philosophy. As the way all things
go, I now have more than 2TB of data saved. Rather than set up another
pair and another set of backup drives, I am seriously considering
obtaining a larger (4TB+) external drive, and set things up as a kind of
continuous backup. The software Western Digital provides with their
drives offers as an option mirroring changes to a source drive to a
secondary drive. That drive, while available in File Explorer, would not
be in active use, but would be a 'dynamic' backup. I would still backup
periodically to my current external drives, but wouldn't have the
overhead of the software RAID, and could probably do a better job of
distributing my data across my drives.

Oh, and I have an APS UPS to help protect agains power failures, surges,
and nasty noise on the power lines.