From: gnuoytr@rcn.com
To: pgsql-performance@postgresql.org
Subject: Re: Reports from SSD purgatory
Date: Wed, 24 Aug 2011 15:42:05 -0400 (EDT)
Message-ID: <201108241942.061270@ms14.lnh.mail.rcn.net> (raw)
In-Reply-To: <d32d411b09d8e7c614772de567a94229.squirrel@sq.gransy.com>
References: <4E49B0A0.2060705@2ndQuadrant.com>
<201108241848.061232@ms14.lnh.mail.rcn.net>
<d32d411b09d8e7c614772de567a94229.squirrel@sq.gransy.com>
---- Original message ----
>Date: Wed, 24 Aug 2011 21:32:16 +0200
>From: pgsql-performance-owner@postgresql.org (on behalf of "Tomas Vondra" <tv@fuzzy.cz>)
>Subject: Re: [PERFORM] Reports from SSD purgatory
>To: gnuoytr@rcn.com
>Cc: pgsql-performance@postgresql.org
>
>On 24 Srpen 2011, 20:48, gnuoytr@rcn.com wrote:
>
>> 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?
>
>Why is that important? It's simply a failure of electronics and it has
>nothing to do with the wear limits. It simply fails without prior warning
>from the SMART.
It matters because if it's the controller, there's nothing one can do about it (the vendor). If it's the NAND, then the vendor/customer can get drives with gooduns rather than baduns. Not necessarily a quick fix, but knowing the quality of the NAND in the SSD you're planning to buy matters.
>
>> Also, given that PG is *nix centric and support for TRIM is win centric,
>> having that makes a big difference in performance.
>
>Windows specific? What do you mean? TRIM is a low-level way to tell the
>drive 'this block is empty and may be used for something else' - it's just
>another command sent to the drive. It has to be supported by the
>filesystem, though (e.g. ext4/btrfs support it).
My point. The firmware and MS have been faster to support TRIM than *nix, linux in particular. Those that won't/can't move to a recent kernel don't get TRIM.
>
>Tomas
>
>
>--
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To: pgsql-performance@postgresql.org
Cc: gnuoytr@rcn.com
Subject: Re: Reports from SSD purgatory
In-Reply-To: <201108241942.061270@ms14.lnh.mail.rcn.net>
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