Received: from localhost (maia-4.hub.org [200.46.204.183]) by postgresql.org (Postfix) with ESMTP id 3C7809FA16F for ; Wed, 6 Dec 2006 12:55:24 -0400 (AST) Received: from postgresql.org ([200.46.204.71]) by localhost (mx1.hub.org [200.46.204.183]) (amavisd-new, port 10024) with ESMTP id 55319-07 for ; Wed, 6 Dec 2006 12:55:16 -0400 (AST) X-Greylist: from auto-whitelisted by SQLgrey-1.7.4 Received: from mir3-fs.mir3.com (mail.mir3.com [65.208.188.100]) by postgresql.org (Postfix) with ESMTP id 02F369F938C for ; Wed, 6 Dec 2006 12:55:16 -0400 (AST) Received: mir3-fs.mir3.com 172.16.1.11 from 172.16.2.68 172.16.2.68 via HTTP with MS-WebStorage 6.0.6249 Received: from archimedes.mirlogic.com by mir3-fs.mir3.com; 06 Dec 2006 08:55:14 -0800 Subject: Re: File Systems Compared From: Mark Lewis To: Brian Wipf Cc: pgsql-performance@postgresql.org In-Reply-To: <82bqmh3rfc.fsf@mid.bfk.de> References: <82bqmh3rfc.fsf@mid.bfk.de> Content-Type: text/plain Content-Transfer-Encoding: 7bit Organization: MIR3, Inc. Date: Wed, 06 Dec 2006 08:55:14 -0800 Message-Id: <1165424114.9734.298.camel@archimedes> Mime-Version: 1.0 X-Mailer: Evolution 2.0.2 (2.0.2-27.rhel4.6) X-Virus-Scanned: Maia Mailguard 1.0.1 X-Archive-Number: 200612/127 X-Sequence-Number: 22183 > Anyone run their RAIDs with disk caches enabled, or is this akin to > having fsync off? Disk write caches are basically always akin to having fsync off. The only time a write-cache is (more or less) safe to enable is when it is backed by a battery or in some other way made non-volatile. So a RAID controller with a battery-backed write cache can enable its own write cache, but can't safely enable the write-caches on the disk drives it manages. -- Mark Lewis