From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from pigeon.gentoo.org ([208.92.234.80] helo=lists.gentoo.org) by finch.gentoo.org with esmtp (Exim 4.60) (envelope-from ) id 1PR5Qy-0004TW-B6 for garchives@archives.gentoo.org; Fri, 10 Dec 2010 16:03:00 +0000 Received: from pigeon.gentoo.org (localhost [127.0.0.1]) by pigeon.gentoo.org (Postfix) with SMTP id 92CC5E0857 for ; Fri, 10 Dec 2010 16:02:59 +0000 (UTC) Received: from mail-ww0-f53.google.com (mail-ww0-f53.google.com [74.125.82.53]) by pigeon.gentoo.org (Postfix) with ESMTP id 0F86DE084F for ; Fri, 10 Dec 2010 15:49:32 +0000 (UTC) Received: by wwi18 with SMTP id 18so3629447wwi.10 for ; Fri, 10 Dec 2010 07:49:32 -0800 (PST) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=gamma; h=domainkey-signature:mime-version:received:sender:reply-to:received :in-reply-to:references:date:x-google-sender-auth:message-id:subject :from:to:content-type; bh=ppFDoHvBRaNih+TDvWA7H/0jEX3iz61gBU6t71E63TE=; b=PdMjk4VlVKtm0+BcJ/fpxLplULWQmqdPz/r8yHv20AL9SQMvp2nylOxulkc+FObMQ1 iEEouzTSGKbrxLVcnj9XoBe2/tNv5vs2fgYDtPEVQoJ4MKtdyGpJd1JoiBLiXnvaFR93 7UxdfwPAA6e14NBuRfis9aZZS4HU4iN2UFxAk= DomainKey-Signature: a=rsa-sha1; c=nofws; d=gmail.com; s=gamma; h=mime-version:sender:reply-to:in-reply-to:references:date :x-google-sender-auth:message-id:subject:from:to:content-type; b=Qf+lxar0CVicH1hwUDOO30EmyS2Rtyry7PQu6vXoSF5LvjTPQfhyWFNq2Y4r5OgJ2z nj3i39FnkevZ1i85uIfsxLY5/GIJ4GSt+FZnucZJqWUJ1ScJ8foSHGQsHSDU972SFkLf JAHiaDAWppfLvqhpMbPYn02NaTYIok2/7uP30= 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 Received: by 10.216.23.18 with SMTP id u18mr2242616weu.92.1291996171811; Fri, 10 Dec 2010 07:49:31 -0800 (PST) Sender: martin.herrman@gmail.com Received: by 10.216.61.18 with HTTP; Fri, 10 Dec 2010 07:49:31 -0800 (PST) In-Reply-To: <4CCD3BB4.6090503@f_philipp.fastmail.net> References: <20101028210453.GB1234@ohnopublishing.net> <4CCD3BB4.6090503@f_philipp.fastmail.net> Date: Fri, 10 Dec 2010 16:49:31 +0100 X-Google-Sender-Auth: -Yta_Mxj3SUSlSunga0aovmaFsE Message-ID: Subject: Re: [gentoo-amd64] Ext3 to ext4 From: Martin Herrman To: gentoo-amd64@lists.gentoo.org Content-Type: text/plain; charset=ISO-8859-1 X-Archives-Salt: 2e2c9dcf-045b-4836-b8b0-efb0ee71a817 X-Archives-Hash: d674b8e7d5cb85d6bbfa86abc01d9d58 2010/10/31 Florian Philipp > > See question 9 here: > http://tldp.org/HOWTO/Software-RAID-0.4x-HOWTO-8.html > > and also the calculator here: > http://busybox.net/~aldot/mkfs_stride.html > > There might be more alignment issues with LVM on RAID. I don't think it > will be a problem as long as LVM's physical extent size (default 4MB) is > a multiple of the RAID stripe size (default 64kB?). Someone with more > experience in these setups than me might want to comment on my guess. Okay, so after a holiday trip, some hard weeks of labour, I went ill. During recovery I decided to dive into this issue again :-) I found out that my current chunk size is 64K: martindesktop ~ # mdadm -Q --detail /dev/md3 Chunk Size : 64K martindesktop ~ # and my block size is 4KiB: martindesktop ~ # /sbin/dumpe2fs /dev/sda3 | grep 'Block size' Block size: 4096 martindesktop ~ # The calculator output is: mkfs.ext3 -b 4096 -E stride=16,stripe-width=32 The maintained RAID howto at: https://raid.wiki.kernel.org/index.php/RAID_setup says that stride and stride-width can be changed afterwards by using: tune2fs -E stride=n,stripe-width=m /dev/mdx So that's what I did: martindesktop / # tune2fs -E stride=16,stripe-width=32 /dev/md3 tune2fs 1.41.12 (17-May-2010) Setting stride size to 16 Setting stripe width to 32 martindesktop / # (this took less than a second) I also read the mdadmin man-page. It looks like one can adjust the chunk size (also for RAID-0) without repartitioning, but I found (using google) no hard evidence that 64K is a wrong choice for a desktop system. I won't perform my own benchmarks (based on what??) and will stick with the 64K. Regards, Martin