X-Original-To: pgsql-general-postgresql.org@localhost.postgresql.org Received: from localhost (mx1.hub.org [200.46.208.251]) by postgresql.org (Postfix) with ESMTP id 568D89F9C9E; Tue, 9 May 2006 14:52:53 -0300 (ADT) Received: from postgresql.org ([200.46.204.71]) by localhost (mx1.hub.org [200.46.208.251]) (amavisd-new, port 10024) with ESMTP id 97807-05; Tue, 9 May 2006 14:52:47 -0300 (ADT) X-Greylist: from auto-whitelisted by SQLgrey- X-Greylist: from auto-whitelisted by SQLgrey- Received: from m.wordtothewise.com (goliath.word-to-the-wise.com [208.187.80.130]) by postgresql.org (Postfix) with ESMTP id DE2CF9F931E; Tue, 9 May 2006 14:52:47 -0300 (ADT) Received: from [10.3.2.7] (184.word-to-the-wise.com [208.187.80.184]) (using TLSv1 with cipher RC4-SHA (128/128 bits)) (No client certificate requested) by m.wordtothewise.com (Postfix) with ESMTP id C3353FF96; Tue, 9 May 2006 10:52:46 -0700 (PDT) Mime-Version: 1.0 (Apple Message framework v749.3) In-Reply-To: <4460BA8B.7010600@commandprompt.com> References: <473FC220-A52C-4954-81E9-A14ED33164C2@blighty.com> <4460BA8B.7010600@commandprompt.com> Content-Type: text/plain; charset=US-ASCII; delsp=yes; format=flowed Message-Id: <4F853BBA-175C-4B3E-BAF4-AA34B80DF6EF@blighty.com> Content-Transfer-Encoding: 7bit From: Steve Atkins Subject: Re: Arguments Pro/Contra Software Raid Date: Tue, 9 May 2006 10:52:45 -0700 To: PostgreSQL General , "Pgsql-Performance ((E-mail))" X-Mailer: Apple Mail (2.749.3) X-Virus-Scanned: Maia Mailguard 1.0.1 X-Archive-Number: 200605/365 X-Sequence-Number: 95157 On May 9, 2006, at 8:51 AM, Joshua D. Drake wrote: ("Using SATA drives is always a bit of risk, as some drives are lying about whether they are caching or not.") >> Don't buy those drives. That's unrelated to whether you use hardware >> or software RAID. > > Sorry that is an extremely misleading statement. SATA RAID is > perfectly acceptable if you have a hardware raid controller with a > battery backup controller. If the drive says it's hit the disk and it hasn't then the RAID controller will have flushed the data from its cache (or flagged it as correctly written). At that point the only place the data is stored is in the non battery backed cache on the drive itself. If something fails then you'll have lost data. You're not suggesting that a hardware RAID controller will protect you against drives that lie about sync, are you? > > And dollar for dollar, SCSI will NOT be faster nor have the hard > drive capacity that you will get with SATA. Yup. That's why I use SATA RAID for all my databases. Cheers, Steve