X-Original-To: pgsql-performance-postgresql.org@localhost.postgresql.org Received: from localhost (av.hub.org [200.46.204.144]) by svr1.postgresql.org (Postfix) with ESMTP id 59F76D7E55 for ; Wed, 14 Sep 2005 15:22:18 -0300 (ADT) Received: from svr1.postgresql.org ([200.46.204.71]) by localhost (av.hub.org [200.46.204.144]) (amavisd-new, port 10024) with ESMTP id 12540-03 for ; Wed, 14 Sep 2005 18:22:12 +0000 (GMT) Received: from mail24.sea5.speakeasy.net (mail24.sea5.speakeasy.net [69.17.117.26]) by svr1.postgresql.org (Postfix) with ESMTP id A7A89D6FD1 for ; Wed, 14 Sep 2005 15:22:11 -0300 (ADT) Received: (qmail 13314 invoked from network); 14 Sep 2005 18:22:12 -0000 Received: from mail.kinesis-cem.com (HELO pdarley) (kinesis@[64.81.9.230]) (envelope-sender ) by mail24.sea5.speakeasy.net (qmail-ldap-1.03) with SMTP for ; 14 Sep 2005 18:22:12 -0000 From: "Peter Darley" To: "Pgsql-Performance" Subject: Battery Backed Cache for RAID Date: Wed, 14 Sep 2005 11:25:38 -0700 Message-ID: MIME-Version: 1.0 Content-Type: text/plain; charset="iso-8859-1" Content-Transfer-Encoding: 7bit X-Priority: 3 (Normal) X-MSMail-Priority: Normal X-Mailer: Microsoft Outlook IMO, Build 9.0.2416 (9.0.2910.0) X-MimeOLE: Produced By Microsoft MimeOLE V6.00.2800.1506 Importance: Normal X-Virus-Scanned: by amavisd-new at hub.org X-Spam-Status: No, hits=0 required=5 tests=[none] X-Spam-Level: X-Archive-Number: 200509/190 X-Sequence-Number: 14498 Folks, I'm getting a new server for our database, and I have a quick question about RAID controllers with a battery backed cache. I understand that the cache will allow the cache to be written out if the power fails to the box, which allows it to report a write as committed safely when it's not actually committed. My question is, if the power goes off, and the drives stop, how does the battery backed cache save things out to the dead drives? Is there another component that is implied that will provide power to the drives that I should be looking into as well? Thanks, Peter Darley