Received: from localhost (maia-4.hub.org [200.46.204.183]) by postgresql.org (Postfix) with ESMTP id 8AB589FB1A5 for ; Wed, 17 Jan 2007 11:57:55 -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 61227-02 for ; Wed, 17 Jan 2007 11:57:22 -0400 (AST) X-Greylist: from auto-whitelisted by SQLgrey-1.7.4 Received: from globalrelay.com (mail1.globalrelay.com [204.92.49.200]) by postgresql.org (Postfix) with ESMTP id 0CC0D9F9FDA for ; Wed, 17 Jan 2007 11:57:21 -0400 (AST) X-Virus-Scanned: Scanned by GRC-AntiVirus Gateway X-GR-Acctd: YES Received: from [71.215.208.64] (HELO DaveEMachine) by globalrelay.com (CommuniGate Pro SMTP 4.2.3) with ESMTP id 123068448 for pgsql-performance@postgresql.org; Wed, 17 Jan 2007 07:57:51 -0800 From: "Dave Dutcher" To: Subject: Raid 10 or Raid 5 on Dell PowerEdge Date: Wed, 17 Jan 2007 09:57:16 -0600 Message-ID: <000401c73a50$29fd4f90$8300a8c0@tridecap.com> MIME-Version: 1.0 Content-Type: text/plain; charset="US-ASCII" Content-Transfer-Encoding: quoted-printable X-Priority: 3 (Normal) X-MSMail-Priority: Normal X-Mailer: Microsoft Outlook, Build 10.0.6822 Importance: Normal Thread-Index: Acc6UCjA8EzfajjYSqK4tuDKKwE0eA== X-MimeOLE: Produced By Microsoft MimeOLE V6.00.2900.3028 X-Virus-Scanned: Maia Mailguard 1.0.1 X-Spam-Status: No, hits=0.004 tagged_above=0 required=5 tests=AWL, BAYES_50 X-Spam-Level: X-Archive-Number: 200701/259 X-Sequence-Number: 22860 Hi. I sent this email to the list last week, but for some reason I = never saw it show up on the list. I apologize if it appears twice now. =20 We recently bought two Dell PowerEdge 2900 servers each with a 2.3 Ghz = 5140 Xeon, 4 Gigs of RAM, 8 15k SAS drives, and a PERC 5/i raid controller = with 256 megs of battery backed cache. Our database is more of an OLTP type, = and everything I've read says that 10 would be better, but I thought I would test both 10 and 5. The other guys here wanted to run the Raid 5 with a = hot spare, so the RAID 10 uses 8 disks and RAID 5 uses 7 plus the hot spare. = We are running CentOS 4.4. I started testing with bonnie++ 1.03a (bonnie++ = -s 16g -x 3 -q ) and I got these numbers. These tests were done with a = RAID stripe size of 64KB, no RAID controller read ahead, and write back = caching enabled. =20 =20 RAID 10 name file_size putc putc_cpu put_block put_block_cpu rewrite = rewrite_cpu=20 Raid10 16G 50546 94 149590 34 81799 = 17=20 Raid10 16G 50722 95 139080 31 82987 = 17=20 Raid10 16G 50526 94 148433 33 82278 = 17=20 getc getc_cpu get_block get_block_cpu seeks seeks_cpu num_files=20 50678 84 236858 30 602.7 1 16=20 50845 85 240024 31 594.8 1 16=20 50921 85 240238 31 547.5 1 16=20 =20 Raid 5 =20 name file_size putc putc_cpu put_block put_block_cpu rewrite = rewrite_cpu =20 Raid5 16G 51253 95 176743 40 87493 = 19=20 Raid5 16G 51349 96 182828 41 89990 = 19=20 Raid5 16G 51627 96 183772 42 91088 = 20=20 getc getc_cpu get_block get_block_cpu seeks seeks_cpu num_files=20 50750 83 232967 29 378.5 0 16=20 51387 84 237049 31 385.0 0 16=20 51241 84 236493 30 391.8 0 16=20 =20 I was somewhat surprised that the RAID 5 was equal or better on almost everything. I assume this must be because it has 6 data disks as = opposed to 4 data disks. The one number that I find strange is the seeks/sec. Is there any reason why a RAID 5 would not be able to seek as quickly as a = RAID 10? Or are the numbers from the Raid 10 bogus? I've also done some = testing with Postgres 8.2.1 and real world queries, and the two machines are basically performing the same, but those seek numbers kinda bug me. Thanks, Dave Dutcher =20