Received: from maia.hub.org (maia-2.hub.org [200.46.204.251]) by mail.postgresql.org (Postfix) with ESMTP id 18E19B5DBF2 for ; Wed, 24 Aug 2011 16:42:14 -0300 (ADT) Received: from mail.postgresql.org ([200.46.204.86]) by maia.hub.org (mx1.hub.org [200.46.204.251]) (amavisd-maia, port 10024) with ESMTP id 60440-03 for ; Wed, 24 Aug 2011 19:42:07 +0000 (UTC) X-Greylist: from auto-whitelisted by SQLgrey-1.7.6 Received: from webmail-out.lnh.mail.rcn.net (webmail-out.lnh.mail.rcn.net [207.172.157.109]) by mail.postgresql.org (Postfix) with ESMTP id BE743B5DBDC for ; Wed, 24 Aug 2011 16:42:06 -0300 (ADT) Received: from ms14.lnh.mail.rcn.net ([208.58.56.82]) by smtp02.lnh.mail.rcn.net with ESMTP; 24 Aug 2011 15:42:06 -0400 Received: (from ms14.lnh.mail.rcn.net [69.183.40.171]) by ms14.lnh.mail.rcn.net (MOS 4.2.3-GA) with HTTP/1.1 id BWR08304 (AUTH gnuoytr@rcn.com); Wed, 24 Aug 2011 15:42:05 -0400 (EDT) From: Subject: Re: Reports from SSD purgatory To: pgsql-performance@postgresql.org X-Mailer: Mirapoint Webmail Direct 4.2.3-GA MIME-Version: 1.0 In-Reply-To: References: <4E49B0A0.2060705@2ndQuadrant.com> <201108241848.061232@ms14.lnh.mail.rcn.net> Message-Id: <201108241942.061270@ms14.lnh.mail.rcn.net> Content-Type: text/plain; charset=us-ascii Content-Transfer-Encoding: 7bit Date: Wed, 24 Aug 2011 15:42:05 -0400 (EDT) X-Virus-Scanned: Maia Mailguard 1.0.1 X-Spam-Status: No, hits=-1.9 tagged_above=-10 required=5 tests=BAYES_00=-1.9 X-Spam-Level: X-Archive-Number: 201108/284 X-Sequence-Number: 44731 ---- Original message ---- >Date: Wed, 24 Aug 2011 21:32:16 +0200 >From: pgsql-performance-owner@postgresql.org (on behalf of "Tomas Vondra" ) >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 > > >-- >Sent via pgsql-performance mailing list (pgsql-performance@postgresql.org) >To make changes to your subscription: >http://www.postgresql.org/mailpref/pgsql-performance