On 10/05/10 20:55, Gary Schrock wrote:
> 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.)
Bad DVDs are no end of trouble. Once I found the TY CDs and DVDs I never
looked back. Also, the write speed matters. I don't go beyond 24x for
CDs and 8x for DVDs. Full face labels are nasty, I think.
For storing them I keep them in a dark place, in a holder for the center
spindle hole, in a plastic case so it doesn't touch anything, stored
upright.
>
> 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.)
Why not keep MD5s for them, and check with those?
>
> 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.
good!
>
> Gary
>
|
