On Fri, Jan 05, 2018 at 09:33:47PM +0000, Bill Gunshannon via cctalk wrote: > Do they also guarantee there will be a device capable of reading it > in 1000 years?
It was bad enough with the BBC Domesday project. Paper. Paper is the only way. acid free paper. > > bill > > ________________________________ > From: cctalk <cctalk-boun...@classiccmp.org> on behalf of Mazzini Alessandro > via cctalk <cctalk@classiccmp.org> > Sent: Friday, January 5, 2018 4:01 PM > To: 'Paul Koning'; 'General Discussion: On-Topic and Off-Topic Posts' > Subject: R: Large discs > > The M kind of dvd supports guarantee over 1000 years of retention, and > resistance to acid/alien invasion/etc > > -----Messaggio originale----- > Da: cctalk [mailto:cctalk-boun...@classiccmp.org] Per conto di Paul Koning > via cctalk > Inviato: venerdì 5 gennaio 2018 21:45 > A: Warner Losh; General Discussion: On-Topic and Off-Topic Posts > Oggetto: Re: Large discs > > > > > On Jan 5, 2018, at 3:24 PM, Warner Losh via cctalk <cctalk@classiccmp.org> > wrote: > > > > On Fri, Jan 5, 2018 at 1:13 PM, Fred Cisin via cctalk > > <cctalk@classiccmp.org > >> wrote: > > > >> On Fri, 5 Jan 2018, Mazzini Alessandro wrote: > >> > >>> I'm not sure I would use SSD for long term "secure" storage, unless > >>> maybe using enterprise level ones. > >>> Consumer level SSD are, by specifics, guaranteed to retain data for > >>> 6 months > >>> > >> > > The JEDEC spec for Consumer grade SSDs is 1 year unpowered at 30C at > > end of life. > > The JEDEC spec for Enterprise grade SSDs is 90 days, unpowered at 30C > > at end of life. > > That's curious. Then again, end of life for enterprise SSDs is many > thousands of write passes over the full disk (or the same amount of writes > to smaller address ranges thanks to remapping). Under high but not insane > loads that takes 5-7 years. So presumably the retention while fairly new > (not very worn) is much better. Still it's surprising to see a number that > small. > > > As far as I've seen, all SATA and NVME drive vendors adhere to these > > specs as a minimum, but there's also a new class of drive for 'cold > storage' > > which has high retention, but low endurance and longer data read times... > > I don't know if the "cold storage" SSD stuff is going anywhere. But in any > case, it seems to aim at high density at the expense of low endurance. I > don't remember hearing retention discussed at all, higher or unchanged. > > Having drives with limited retention seems quite problematic. And > "unpowered" suggests that leaving the power on would help -- but I don't see > why that would be so. > > As for writable DVDs and such, do they have any useful retention specs? > > paul > -- - d...@freebsd.org d...@db.net http://www.db.net/~db
