Received: from localhost (unknown [200.46.204.183]) by mail.postgresql.org (Postfix) with ESMTP id 8D93864FD49 for ; Sat, 22 Nov 2008 12:16:58 -0400 (AST) Received: from mail.postgresql.org ([200.46.204.86]) by localhost (mx1.hub.org [200.46.204.183]) (amavisd-maia, port 10024) with ESMTP id 37327-05 for ; Sat, 22 Nov 2008 12:16:55 -0400 (AST) X-Greylist: domain auto-whitelisted by SQLgrey-1.7.6 Received: from wa-out-1112.google.com (wa-out-1112.google.com [209.85.146.183]) by mail.postgresql.org (Postfix) with ESMTP id 9570C64FC5C for ; Sat, 22 Nov 2008 12:16:55 -0400 (AST) Received: by wa-out-1112.google.com with SMTP id j4so712356wah.19 for ; Sat, 22 Nov 2008 08:16:54 -0800 (PST) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=gamma; h=domainkey-signature:received:received:message-id:date:from:to :subject:cc:in-reply-to:mime-version:content-type :content-transfer-encoding:content-disposition:references; bh=j8jbxC7DcD+drI8QbQGQxtNqo1hwRtKUTNihwwKAokQ=; b=nbFiURAin1RiL3aV+73WC88ODdZT/8izjepsdCLyg/rK7bbZgSVvJXjr21Yf93/Vvn iaREgXTqsmDA3LA5AzxvF7WaE+ES1NQK98EEpy0epoIjvy46x+KP1YxDrJopi3CAIbS6 vDt326JVdKQFDBRwHIJR7vSA9HB2DmrXHAI4I= DomainKey-Signature: a=rsa-sha1; c=nofws; d=gmail.com; s=gamma; h=message-id:date:from:to:subject:cc:in-reply-to:mime-version :content-type:content-transfer-encoding:content-disposition :references; b=GH0RXXH9Qc3Jp/UZ1urxGGbjSjF49iN5gK2/8w+rXB7mQ4zI3mhmsYOl4JDwtT4H1p H28As6yXW5AGTD3fXQZVOcWnrBsruCulOd2JUbvtE3UOrMUao/JU4MmlxUp0G+L+EtIV QNP057i8xJ3HeG3mwVB6aLWPR6nPHyMhF2mHs= Received: by 10.114.175.16 with SMTP id x16mr954417wae.134.1227370614596; Sat, 22 Nov 2008 08:16:54 -0800 (PST) Received: by 10.114.133.14 with HTTP; Sat, 22 Nov 2008 08:16:54 -0800 (PST) Message-ID: Date: Sat, 22 Nov 2008 09:16:54 -0700 From: "Scott Marlowe" To: glynastill@yahoo.co.uk Subject: Re: Perc 3 DC Cc: pgsql-performance@postgresql.org In-Reply-To: <680067.16755.qm@web23608.mail.ird.yahoo.com> MIME-Version: 1.0 Content-Type: text/plain; charset=ISO-8859-1 Content-Transfer-Encoding: 7bit Content-Disposition: inline References: <680067.16755.qm@web23608.mail.ird.yahoo.com> X-Virus-Scanned: Maia Mailguard 1.0.1 X-Spam-Status: No, hits=0 tagged_above=0 required=5 tests=none X-Spam-Level: X-Archive-Number: 200811/201 X-Sequence-Number: 31932 On Sat, Nov 22, 2008 at 7:18 AM, Glyn Astill wrote: > Hi chaps, > > I've had this old card sitting on my desk for a while. It appears to be a U160 card with 128Mb BBU so I thought I'd wang it in my test machine (denian etch) and give it a bash. > > I set up 4 36Gb drives in raid 0+1, but I don't seem to be able to get more than 20MB/s write speed out of it for large files (2XRAM usual tests with dd from dev/zero). I don't expect anything great, but I thought it'd do a little better than that. You really have two choices. First is to try and use it as a plain SCSI card, maybe with caching turned on, and do the raid in software. Second is to cut it into pieces and make jewelry out of it. Anything before the Perc 6 series is seriously brain damaged, and the Perc6 brings the dell raid array line squarly in line with a 5 year old LSI megaraid, give or take. And that's being generous. > I've tried writeback and write through modes, tried changing cache flush times, disabled and enabled multiple PCI delayed transactions, all seem to have little effect. Yeah, it's like trying to performance tune a yugo. > Finally I decided to wave goodbye to Dell's firmware. LSI has it down as a MegaRAID 493 elite 1600, so I flashed it with their latest firmware. Doesn't seem to have helped either though. Does it have a battery backup module? Often you can't really turn on write-back without one. That would certainly slow things down. But you should certainly expect > 20 M/s on a modern RAID controller writing out to a 4 disk RAID10 > Has anybody else used this card in the past? I'm wondering if this is a driver issue, or if the card is and always was just crap? If so I'll proabably try sw raid on it instead. It's pretty much a low end card. Look into modern LSI, Areca, or Escalade/3Ware cards if you want good performance.