R: Large discs (Was: Spectre & Meltdown

Warner Losh imp at bsdimp.com
Fri Jan 5 14:24:04 CST 2018

On Fri, Jan 5, 2018 at 1:13 PM, Fred Cisin via cctalk <cctalk at 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
The JEDEC spec for Enterprise grade SSDs is 90 days, unpowered at 30C at
end of life.

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...

> if unpowered... any more time means being lucky. Would suck to save, store,
>> and after some years find the data mangled...
> Yep!
> SSD would be very unsuitable for archiving.

Unworn (meaning only a few P/E cycles) SSDs made from MLC or SLC NAND have
data retention measured in the decade range. Stored at 0C, these would have
~300 year data retention since every 10C below the benchmark temperature
gives you 3x longer retention. Conversely, storing at 40C or 50C puts the
data at risk.

Worn (meaning near end of life) SSDs, especially those that have been
pushed past end of life, have issues.

But, it is a nice fast medium for short-term uses.
> AND, it MIGHT be the first to get a unit larger than 2TB that will fit in
> a thin 2.5" form factor.
> Probably better SHORT-TERM reliability than the Seagate 2TB thin SATA
> spinning rust.
> What is the archival life of a BDXL, other than M-disc?
> M-disc media is a bit expensive.
> It looks like an excellent medium for data collections a tenth the size of
> what I'm playing with.
> It seems that it is still necessary to maintain multiple copies
> (geographically separate - we had a 4.4 quake yesterday morning), on
> multiple different media, and make new copies on a regular basis.

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