Received: from maia.hub.org (maia-3.hub.org [200.46.204.243]) by mail.postgresql.org (Postfix) with ESMTP id EABA4B5DC0C for ; Tue, 19 Jul 2011 04:57:08 -0300 (ADT) Received: from mail.postgresql.org ([200.46.204.86]) by maia.hub.org (mx1.hub.org [200.46.204.243]) (amavisd-maia, port 10024) with ESMTP id 78652-03 for ; Tue, 19 Jul 2011 07:57:02 +0000 (UTC) X-Greylist: from auto-whitelisted by SQLgrey-1.7.6 Received: from mx01.bfk.de (mx01.bfk.de [193.227.124.2]) by mail.postgresql.org (Postfix) with ESMTP id 1EAFCB5DBD5 for ; Tue, 19 Jul 2011 04:57:01 -0300 (ADT) Received: from mx00.int.bfk.de ([10.119.110.2]) by mx01.bfk.de with esmtps (TLS1.0:RSA_AES_256_CBC_SHA1:32) id 1Qj5Al-0004fv-59; Tue, 19 Jul 2011 07:56:55 +0000 Received: by bfk.de with local id 1Qj5Al-0001pS-0N; Tue, 19 Jul 2011 07:56:55 +0000 From: Florian Weimer To: Yeb Havinga Cc: Andy , pgsql-performance@postgresql.org Subject: Re: BBU still needed with SSD? References: <1310953399.25726.YahooMailClassic@web111304.mail.gq1.yahoo.com> <4E23E72B.2070508@gmail.com> Date: Tue, 19 Jul 2011 07:56:54 +0000 In-Reply-To: <4E23E72B.2070508@gmail.com> (Yeb Havinga's message of "Mon, 18 Jul 2011 09:56:27 +0200") Message-ID: <82vcuyd7p5.fsf@mid.bfk.de> MIME-Version: 1.0 Content-Type: text/plain; charset=iso-8859-1 Content-Transfer-Encoding: quoted-printable X-Virus-Scanned: Maia Mailguard 1.0.1 X-Spam-Status: No, hits=-3.035 tagged_above=-10 required=5 tests=BAYES_00=-1.9, RP_MATCHES_RCVD=-1.135 X-Spam-Level: X-Archive-Number: 201107/188 X-Sequence-Number: 44400 * Yeb Havinga: > The biggest drawback of 2 SSD's with supercap in hardware raid 1, is > that if they are both new and of the same model/firmware, they'd > probably reach the end of their write cycles at the same time, thereby > failing simultaneously. I thought so too, but I've got two Intel 320s (I suppose, the report device model is "SSDSA2CT040G3") in a RAID 1 configuration, and after about a month of testing, one is down to 89 on the media wearout indicator, and the other is still at 96. Both devices are deteriorating, but one at a significantly faster rate. --=20 Florian Weimer BFK edv-consulting GmbH http://www.bfk.de/ Kriegsstra=DFe 100 tel: +49-721-96201-1 D-76133 Karlsruhe fax: +49-721-96201-99