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Re: Reports from SSD purgatory

From: Merlin Moncure <mmoncure(at)gmail(dot)com>
To: gnuoytr(at)rcn(dot)com
Cc: pgsql-performance(at)postgresql(dot)org
Subject: Re: Reports from SSD purgatory
Date: 2011-08-24 18:54:57
Message-ID: CAHyXU0zJESnMfQ2+-1tyoQARf5ert9Nq+zhgWYT374Tdk5GGNg@mail.gmail.com (view raw or flat)
Thread:
Lists: pgsql-performance
On Wed, Aug 24, 2011 at 1:48 PM,  <gnuoytr(at)rcn(dot)com> wrote:
>
>
> ---- Original message ----
>>Date: Mon, 15 Aug 2011 19:49:52 -0400
>>From: pgsql-performance-owner(at)postgresql(dot)org (on behalf of Greg Smith <greg(at)2ndQuadrant(dot)com>)
>>Subject: [PERFORM] Reports from SSD purgatory
>>To: "pgsql-performance(at)postgresql(dot)org" <pgsql-performance(at)postgresql(dot)org>
>>
>>News update for anyone else who's trapped like me, waiting for a fix to
>>the Intel 320 SSD bug where they can truncate themselves to 8MB.  Over
>>the weekend Intel has announced a firmware fix for the problem is done,
>>and is due to ship "within the next two weeks":
>>http://communities.intel.com/thread/24121
>>
>>On the larger SSD reliability front, Tom's Hardware surveyed heavy SSD
>>users they're friendly with who use Intel drives.  The most interesting
>>data came from Softlayer:
>>http://www.tomshardware.com/reviews/ssd-reliability-failure-rate,2923-6.html
>>
>>This supports two claims I made before based on my private data that
>>were controversial:
>>
>>-Annualized SSD failure rates are not significantly lower than
>>traditional drives in the first couple of years.  Jury is still out on
>>whether they will spike upwards starting at 3 years as mechanical ones do.
>>
>>-The most common source of dead drives is sudden, catastrophic
>>electronics failure.  These are not predicted by SMART, and have nothing
>>to do with hitting the drive's wear limits.
>
> It's worth knowing exactly what that means.  Turns out that NAND quality is price specific.  There's gooduns and baduns.  Is this a failure in the controller(s) or the NAND?
>
> Also, given that PG is *nix centric and support for TRIM is win centric, having that makes a big difference in performance.

one point about TRIM -- no raid controller that I know of supports
trim, which suggests it might not even be possible to support.  How
much does it help really? Probably not as much as you would think
because newer SSD drives have very sophisticated controllers that make
it at least partially obsolete.

merlin

merlin

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