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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 >