Received: from localhost (unknown [200.46.204.182]) by postgresql.org (Postfix) with ESMTP id 37A2E2E0239 for ; Wed, 26 Dec 2007 15:32:06 -0400 (AST) Received: from postgresql.org ([200.46.204.71]) by localhost (mx1.hub.org [200.46.204.182]) (amavisd-maia, port 10024) with ESMTP id 63887-03 for ; Wed, 26 Dec 2007 15:31:55 -0400 (AST) Received: from pyxis.powervt.com.ar (host6.powervt.com.ar [200.43.63.66]) by postgresql.org (Postfix) with ESMTP id C0C092E2F7B for ; Wed, 26 Dec 2007 15:32:02 -0400 (AST) Received: from pcfhevia ([201.216.249.98]) by pyxis.powervt.com.ar (IPGroup Mail Server) with ESMTP id 1OT48953; Wed, 26 Dec 2007 16:32:01 -0300 From: "Fernando Hevia" To: "'Mark Mielke'" Cc: "'pgsql-performance'" Subject: Re: With 4 disks should I go for RAID 5 or RAID 10 Date: Wed, 26 Dec 2007 16:32:21 -0300 Organization: IP-TEL Message-ID: <0f8201c847f6$08e15090$8f01010a@iptel.com.ar> MIME-Version: 1.0 Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit X-Mailer: Microsoft Office Outlook 11 In-Reply-To: <47728000.4000709@mark.mielke.cc> Thread-Index: AchH3BdWYUZsOQN3SV2flaSC9a9algAGZrtQ X-MimeOLE: Produced By Microsoft MimeOLE V6.00.2900.3198 X-Virus-Scanned: Maia Mailguard 1.0.1 X-Archive-Number: 200712/367 X-Sequence-Number: 28183 Mark Mielke Wrote: >In my experience, software RAID 5 is horrible. Write performance can >decrease below the speed of one disk on its own, and read performance will >not be significantly more than RAID 1+0 as the number of stripes has only >increased from 2 to 3, and if reading while writing, you will not get 3X as >RAID 5 write requires at least two disks to be involved. I believe hardware >RAID 5 is also horrible, but since the hardware hides it from the >application, a hardware RAID 5 user might not care. >Software RAID 1+0 works fine on Linux with 4 disks. This is the setup I use >for my personal server. I will use software RAID so RAID 1+0 seems to be the obvious choice. Thanks for the advice!