5 Jan
2018
5 Jan
'18
4:33 p.m.
Do they also guarantee there will be a device capable of reading it
in 1000 years?
bill
________________________________
From: cctalk <cctalk-bounces at classiccmp.org> on behalf of Mazzini Alessandro via
cctalk <cctalk at 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-bounces at classiccmp.org] Per conto di Paul Koning
via cctalk
Inviato: venerd? 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 at classiccmp.org>
wrote:
On Fri, Jan 5, 2018 at 1:13 PM, Fred Cisin via cctalk
<cctalk at classiccmp.org
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.
wrote:
On Fri, 5 Jan 2018, Mazzini Alessandro wrote:
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. 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
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