STeve Andre' wrote:
> What I'm doing--and I have a limited amount of 'super-critical' data--is
> to store stuff on Taiyo-Yuden DVDs. I use these specifically, because of
> the chemistry they use for the dye, such that they ought to last a long
> time, in the range of several decades. TY says more than 50, and even
> their detractors say a "long time", so I think that's the longest term non
> solid-state way to save data. I'm not sure that disks won't last a long
> time either. I have some ST-225's that powered up and worked three
> years ago, and they're *old*. How today's hundred-gig disks will fare I
> can't say. I know I have at least 5 8G-or-smaller disks that still work
> that are from 1993 to 1998 or so.
>
> If worried about a DVD failing, don't roast one, roast five, or any
> number. It isn't hard to take N DVD drives and write software to
> take N copies of a DVD and walk through them together, voting to
> throw out any set of bad data. Yes, there is still a chance that a set
> of DVD's could have bad spots on all of them, but I don't think its
> likely. Yeah, I know: backing up a 1T disk is much like backing up
> a 30M IBM-AT with floppies. Ugh!
FWIW, I've had enough trouble with various writable dvd's over the years
that I wouldn't trust them. Enough so that at the very least, I'd never
consider keeping anything I'd consider important on a single dvd-r.
CD-r's to me seem to have survived far better. (Although obviously,
they're not all that useful these days for large sets of data.) But
I've got hundreds of written dvd's and cd's at home, and I've had enough
trouble with dvd's over 3 years old or so to make me leary. (And the
incidence of problems goes *way* up on dvd's that had full face labels
applied to them, I'll never use them on a dvd again.)
Since I can't afford a nice tape library at home, for me my method has
been multiple external hard drives, rotating some backups between them.
I'm not necessarily completely happy with the system, because I'm
not completely happy with my tests for data integrity. (And believe me,
I've spent a fair amount of time trying to come up with a way I was
happy with that I could implement with as little effort as possible.)
I'd be happier if I could find a good way to assure that the data that
I'm copying is indeed intact and not corrupt. But like the dvd method,
this is really safety through multiple duplication, so the only real
advantage to this is that it's a lot easier to deal with than dvd's are
when you have hundred of gigs to back up. (And let's face it, digital
photography and video adds up awfully quick.)
Ideally of course, at least one of those copies should be stored at a
different location to protect from disaster. I've been nowhere near as
good as I should be with doing this for my personal stuff from home.
This does remind me that I haven't backed my stuff up at home recently,
so I think I'm going to go ahead and take care of that.
Gary
