Hi Reese,
How's it going? Good to hear from you.
Thanks for that link. That TechReport endurance test is pretty
interesting. I had looked it in the past but hadn't seen the most
recent stuff. I looked at the link you mentioned. Also, someone on
another forum sent me a link to a more recent article on the same site.
http://techreport.com/review/26523/the-ssd-endurance-experiment-casualties-on-the-way-to-a-petabyte
3 of the 6 drives have failed at this point. This article is very
interesting. I've read it briefly and will be reading it again. I
think there are some interesting conclusions to be drawn. I THINK the
graph on p3 of this latter article regarding the Samsung 840 Pro
indirectly answers my endurance question. Even though it is still going
after 1000 TB, their wear leveling indicator, which is supposed to be
related to drive health, bottomed out around 400 TB. This seems to
corroborate my theory that the drive might be rated for between 300 TB
and 400 TB of writes. And, the one they're testing certainly seems
viable well beyond that. Doing some math using a 256 GB drive and 400
TB of writes would yield an endurance figure of around 1500 p/e cycles
design life. However, since the drive is still going after 1000 TB,
that drive may be capable of supporting 3900 p/e cycles. That would be
consistent with MLC cells in general, which are usually in the range of
3000 p/e cycles. Of course that probably depends on process node size.
I don't like the way some drives decided to brick themselves at the end
of their life, rather than being readable continuously. I tend to run
things till they die, so it would be nice if they give warning before
that. Also, I'd still like to see a 90 day power off data retention
test for the used drives.
Hope you had a good 4th of July. My wife and I did a bit of shopping
(in opposite directions - we like different things), did some walking in
the park, and watched the Macy's NY fireworks on tv.
Sincerely,
Ron
On 7/6/2014 12:40 PM, Reese Johnson wrote:
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Hash: SHA1
What's up Ron! I think I have a 840 in my big laptop. Reading your
questions reminded me of a test I had read about. I think this is the
link for it.
http://techreport.com/review/26058/the-ssd-endurance-experiment-data-retention-after-600tb
Have a safe holiday weekend
On 07/06/2014 08:00 AM, [email protected] wrote:
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Today's Topics:
1. anybody know endurance rating of samsung 840 pro ssd? (Ron
Frazier (TECHC))
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Message: 1 Date: Sat, 05 Jul 2014 11:25:53 -0400 From: "Ron
Frazier (TECHC)"<[email protected]> To: Tech Chat
List<[email protected]> Subject: [tech-chat] anybody know
endurance rating of samsung 840 pro ssd? Message-ID:
<[email protected]>
Content-Type: text/plain; charset=UTF-8
Hi all,
I'm studying ssd's again and wanting to buy one, even if it's
small. Two fabulous contenders are the samsung 840 pro and the
samsung 850 pro (soon to be released).
The 840 pro uses MLC flash and has a 5 year warranty.
The 850 pro uses VERTICAL flash and has a 10 year warranty at 150
TB written or about 41 GB / day. If you do the math on a 128 GB
drive, this amounts to only about 1171 program / erase cycles. For
larger drives with the same rating, it amounts to even fewer p/e
cycles, getting down to 150 p/e cycles for a 1 TB drive. That
number is pretty appalling.
The MLC flash in the 840 pro SHOULD be good for about 3000 p/e
cycles, which would mean the drive can support writes of about 384
TB. TechReport has pushed one of these to over 500 TB of writes,
with no unrecoverable errors, which would tend to support this
theory. (I would be suspect of long term data retention with power
off after that many writes though.)
BUT, I haven't been able to find an endurance spec anywhere on the
840 pro. Has anybody seen any credible data on this?
The tradeoff seems to be:
840 pro, potentially longer actual endurance, shorter warranty,
somewhat slower performance
850 pro, potentially shorter actual endurance, longer warranty,
somewhat higher performance
similar prices, both support trim, both support encryption (I
think)
Any help is appreciated.
Sincerely,
Ron
--
(PS - If you email me and don't get a quick response, you might want to
call on the phone. I get about 300 emails per day from alternate energy
mailing lists and such. I don't always see new email messages very quickly.)
Ron Frazier
770-205-9422 (O) Leave a message.
linuxdude AT techstarship.com
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