From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from lists.gentoo.org (pigeon.gentoo.org [208.92.234.80]) by finch.gentoo.org (Postfix) with ESMTP id 873961381F3 for ; Thu, 20 Jun 2013 19:31:26 +0000 (UTC) Received: from pigeon.gentoo.org (localhost [127.0.0.1]) by pigeon.gentoo.org (Postfix) with SMTP id 20E0FE0AB2; Thu, 20 Jun 2013 19:31:20 +0000 (UTC) Received: from mail-pa0-f44.google.com (mail-pa0-f44.google.com [209.85.220.44]) (using TLSv1 with cipher ECDHE-RSA-RC4-SHA (128/128 bits)) (No client certificate requested) by pigeon.gentoo.org (Postfix) with ESMTPS id 43B13E09F5 for ; Thu, 20 Jun 2013 19:31:19 +0000 (UTC) Received: by mail-pa0-f44.google.com with SMTP id lj1so6663892pab.3 for ; Thu, 20 Jun 2013 12:31:18 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=20120113; h=mime-version:in-reply-to:references:date:message-id:subject:from:to :content-type; bh=WG+fFqQDpZfDUGaKm/LXklIeSRahVfV38AS9xYEXsHA=; b=cyIjxuAvfLUVHkRJk0MwSNq+Z4tiws0M06Rz/388NpskL/7a8YBWsd58rGv9Wf5eej MngcrcIMtYFHeM0qWNoIC078OGQ+yMSKWlAbhOQ994xwZRRqm2cMwI5N57qfgh7PA8fw 8Q5g2t3tBNp7gIzG9rvhEs48IfH6UMAXjifIEMvn1ZzD7gsSFHJxUBZMCKGle1ZvfdcE iWNGPnLBjIvZN14bUboaY8fSeiEv0a44k2KN/s2OvZ+kteHRZms4oPkwd8L6JOH2NxYy VFuvtHNMXV0yI+gXFTUlNxSe91GnzS0P2tJYSQ/BMeCmNkn8dVMNdkc/htz1aerIQflb b/9w== Precedence: bulk List-Post: List-Help: List-Unsubscribe: List-Subscribe: List-Id: Gentoo Linux mail X-BeenThere: gentoo-amd64@lists.gentoo.org Reply-to: gentoo-amd64@lists.gentoo.org MIME-Version: 1.0 X-Received: by 10.68.143.5 with SMTP id sa5mr8961043pbb.106.1371756678111; Thu, 20 Jun 2013 12:31:18 -0700 (PDT) Received: by 10.70.33.198 with HTTP; Thu, 20 Jun 2013 12:31:18 -0700 (PDT) In-Reply-To: References: Date: Thu, 20 Jun 2013 12:31:18 -0700 Message-ID: Subject: Re: [gentoo-amd64] Is my RAID performance bad possibly due to starting sector value? From: Mark Knecht To: Gentoo AMD64 Content-Type: text/plain; charset=UTF-8 X-Archives-Salt: 004b0c4b-4835-4c76-bf01-3bb2d97dcf19 X-Archives-Hash: e368ce4dffde96a5a9d91578b76e3395 On Thu, Jun 20, 2013 at 12:27 PM, Rich Freeman wrote: > On Thu, Jun 20, 2013 at 3:10 PM, Mark Knecht wrote: >> Looking for some thoughtful ideas from those more experienced in this area. > > Please do share your findings. I suspect my own RAID+LVM+EXT3/4 > system is not optimized - especially with LVM I have no idea how > blocks in ext3/4 end up mapping to stripes and physical blocks. Oh, > and this is on 4k disks. > > Honestly, this is one of the reasons I REALLY want to move to btrfs > when it fully supports raid5. Right now the various layers don't talk > to each other and that means a lot of micro-management if you don't > want a lot of read-write-read cycles (to say nothing of what you can > buy with a filesystem that can aim to overwrite entire stripes at a > time). > > Rich > I'll share everything I find, true or false, and maybe as a group we can figure out what's right. In the meantime, please be careful with your RAID5 and do good backups :-) I ran RAID5 for awhile but moved to RAID6 due to the number of reports I read where one drive went bad on a RAID5 and then the RAID lost a second drive before the original bad drive was replaced and everything was gone. Cheers, Mark