[geeks] Cheap/reliable backup?

[Mouse]

> Is there a cheap/reliable way to backup data from a disk?

Insufficient information.  Why do you want backups?  What OS?  What
other tradeoffs?

There are three purposes I've identified that backups serve:

(1) Mistake recovery: "Oops, I didn't mean to delete that."
(2) Historical queries: "This worked last May, what was here then?"
(3) Failure recovery: "Oh $h1+, the disk just died."

Some mechanisms are better suited to one than another; for example, my
own backup system is tuned for dealing (3) - it doesn't even try to
address (1) or (2).  (It could be modified a bit to handle them.)

> I don't usually hear about the latest tech stuff for a decade or so
> but it seems to me the only thing people are doing to backup their
> data is mirroring it (not exactly a backup but good if one disk
> suddenly fails)

How is it not a backup?  It's mostly good for (3), and it's what I do
for backups.  If you periodically swap out one backup drive and swap in
another, it can serve for (1) and (2) too.

For most purposes, I wouldn't consider tape; given the relative sizes
and costs of tapes and disks, disks are mostly better.  One of my
workplaces did that - we determined that disk drives were higher
capacity and lower cost than the tapes we were using, and offered
relatively random access to the data besides.  (Really, pretty much the
only downside was physical ruggedness, which wasn't important enough to
us to win over the other considerations.)  Use a hot-pluggable drive
interface - SCA SCSI, SATA, SAS - with a hot-plug drive bay and it even
has the removability of tape.  For our purposes, a USB SATA drive bay
turned out to be a good answer (USB 2.0 was fast enough for us).

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