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 9878D1381F3 for ; Sun, 23 Jun 2013 11:43:45 +0000 (UTC) Received: from pigeon.gentoo.org (localhost [127.0.0.1]) by pigeon.gentoo.org (Postfix) with SMTP id D052DE099B; Sun, 23 Jun 2013 11:43:35 +0000 (UTC) Received: from mail-ve0-f182.google.com (mail-ve0-f182.google.com [209.85.128.182]) (using TLSv1 with cipher ECDHE-RSA-RC4-SHA (128/128 bits)) (No client certificate requested) by pigeon.gentoo.org (Postfix) with ESMTPS id 0FBF3E094F for ; Sun, 23 Jun 2013 11:43:34 +0000 (UTC) Received: by mail-ve0-f182.google.com with SMTP id ox1so7861662veb.27 for ; Sun, 23 Jun 2013 04:43:34 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=20120113; h=mime-version:sender:in-reply-to:references:date :x-google-sender-auth:message-id:subject:from:to:content-type; bh=SrRJk5kUFAD+bTN64VPBKpGu16oWV5PlzJIPGLqzvt8=; b=n+hxQohjmpuST+mWIcNRxkw11hr8X1zs5aipLmPMU1D++Y5M7HvGZ6LOhFEINTRQEO etmwiLsEBada7WcERTc0UHClH9fxA9O4M57sCYl8xujfvl8drgQ7jkvz42++itGauO07 kKCDlzJAR24Wmpuv9E603E0AH9sqwuff7Vmd9H4Omt/t04dn+SdXEBkfEeYmmA5qnD4Y gqvp5iS/YgaZkdmcOVbNGII35lYc+poRg7WEXIG0yYrCWEP2Yk6Sk1CxW6xjW+xiKuXM rwu5D1YPsulzIgXPIMhUnogIIwMEGj323tRMiyC+wSOclB9WtJFd2xFSqQHKnkckOu0i w6Dg== 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 10.58.182.103 with SMTP id ed7mr9578749vec.70.1371987814210; Sun, 23 Jun 2013 04:43:34 -0700 (PDT) Sender: freemanrich@gmail.com Received: by 10.52.180.98 with HTTP; Sun, 23 Jun 2013 04:43:34 -0700 (PDT) In-Reply-To: References: Date: Sun, 23 Jun 2013 07:43:34 -0400 X-Google-Sender-Auth: 56ebi-uu-XeuoSYGotw3ifZnsUA Message-ID: Subject: Re: [gentoo-amd64] Re: Is my RAID performance bad possibly due to starting sector value? From: Rich Freeman To: gentoo-amd64@lists.gentoo.org Content-Type: text/plain; charset=ISO-8859-1 X-Archives-Salt: 5bcdd6f1-bb6e-497e-a3b7-e97c1b0316b8 X-Archives-Hash: b40dbd6f76d71195a6f8294c0a1cf764 On Sat, Jun 22, 2013 at 7:04 PM, Mark Knecht wrote: > I've been rereading everyone's posts as well as trying to collect > my own thoughts. One question I have at this point, being that you and > I seem to be the two non-RAID1 users (but not necessarily devotees) at > this time, is what chunk size, stride & stripe width with you are > using? I'm using 512K chunks on the two RAID5s which are my LVM PVs: md7 : active raid5 sdc3[0] sdd3[6] sde3[7] sda4[2] sdb4[5] 971765760 blocks super 1.2 level 5, 512k chunk, algorithm 2 [5/5] [UUUUU] bitmap: 1/2 pages [4KB], 65536KB chunk md6 : active raid5 sda3[0] sdd2[4] sdb3[3] sde2[5] 2197687296 blocks super 1.2 level 5, 512k chunk, algorithm 2 [4/4] [UUUU] bitmap: 2/6 pages [8KB], 65536KB chunk On top of this I have a few LVs with ext4 filesystems: tune2fs -l /dev/vg1/root | grep RAID RAID stride: 128 RAID stripe width: 384 (this is root, bin, sbin, lib) tune2fs -l /dev/vg1/data | grep RAID RAID stride: 19204 (this is just about everything else) tune2fs -l /dev/vg1/video | grep RAID RAID stride: 11047 (this is mythtv video) Those were all the defaults picked, and with the exception of root I believe the array was quite different when the others were created. I'm pretty confident that none of these are optimizes, and I'd be shocked if any of them are aligned unless this is automated (including across pvmoves, reshaping, and such). That is part of why I'd like to move to btrfs - optimizing raid with mdadm+lvm+mkfs.ext4 involves a lot of micromanagement as far as I'm aware. Docs are very spotty at best, and it isn't at all clear that things get adjusted as needed when you actually take advantage of things like pvmove or reshaping arrays. I suspect that having btrfs on bare metal will be more likely to result in something that keeps itself in-tune. Rich