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 686A6D6853 for ; Wed, 16 Nov 2005 17:04:47 -0400 (AST) 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 46778-01 for ; Wed, 16 Nov 2005 21:04:48 +0000 (GMT) X-Greylist: from auto-whitelisted by SQLgrey- Received: from floppy.pyrenet.fr (floppy.pyrenet.fr [194.116.145.2]) by svr1.postgresql.org (Postfix) with ESMTP id 59E5BD8CA0 for ; Wed, 16 Nov 2005 17:04:44 -0400 (AST) Received: by floppy.pyrenet.fr (Postfix, from userid 106) id C8C0731058; Wed, 16 Nov 2005 22:04:45 +0100 (MET) From: Ron Mayer X-Newsgroups: pgsql.performance Subject: Re: Hardware/OS recommendations for large databases ( Date: Wed, 16 Nov 2005 13:08:58 -0800 Organization: Hub.Org Networking Services Lines: 42 Message-ID: <437B9FEA.5010003@cheapcomplexdevices.com> References: <3E37B936B592014B978C4415F90D662D01995F7B@MI8NYCMAIL06.Mi8.com> <33c6269f0511152115v1a34ab81j30f1f5df5a6c6956@mail.gmail.com> <437B3B18.1040509@commandprompt.com> <437B4773.1040404@boreham.org> Mime-Version: 1.0 Content-Type: text/plain; charset=windows-1252; format=flowed Content-Transfer-Encoding: 8bit X-Complaints-To: usenet@news.hub.org To: William Yu User-Agent: Mozilla Thunderbird 1.0 (Windows/20041206) X-Accept-Language: en-us, en In-Reply-To: To: pgsql-performance@postgresql.org X-Virus-Scanned: by amavisd-new at hub.org X-Spam-Status: No, score=0 required=5 tests=[none] X-Spam-Score: 0 X-Spam-Level: X-Archive-Number: 200511/301 X-Sequence-Number: 15558 William Yu wrote: > > Our SCSI drives have failed maybe a little less than our IDE drives. Microsoft in their database showcase terraserver project has had the same experience. They studied multiple configurations including a SCSI/SAN solution as well as a cluster of SATA boxes. They measured a 6.4% average annual failure rate of their SATA version and a 5.5% average annual failure rate on their SCSI implementation. ftp://ftp.research.microsoft.com/pub/tr/TR-2004-107.pdf "We lost 9 drives out of 140 SATA drives on the Web and Storage Bricks in one year. This is a 6.4% annual failure rate. In contrast, the Compaq Storageworks SAN and Web servers lost approximately 32 drives in three years out of a total of 194 drives.13 This is a 5.5% annual failure rate. The failure rates indicate that SCSI drives are more reliable than SATA. SATA drives are substantially cheaper than SCSI drives. Because the SATA failure rate is so close to the SCSI failure rate gives SATA a substantial return on investment advantage." So unless your system is extremely sensitive to single drive failures, the difference is pretty small. And for the cost it seems you can buy enough extra spindles of SATA drives to easily make up for the performance difference. > Basically, I've found it's cooling that's most important. Packing the > drives together into really small rackmounts? Good for your density, not > good for the drives. Indeed that was their guess for their better-than-expected life of their SATA drives as well. From the same paper: "We were careful about disk cooling – SATA drives are rarely cooled with the same care that a SCSI array receives."