From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from mx1.redhat.com (ext-mx14.extmail.prod.ext.phx2.redhat.com [10.5.110.19]) by int-mx09.intmail.prod.int.phx2.redhat.com (8.14.4/8.14.4) with ESMTP id q1RKeWk1022832 for ; Mon, 27 Feb 2012 15:40:32 -0500 Received: from www.bettercgi.com (www.bettercgi.com [74.122.122.24]) by mx1.redhat.com (8.14.4/8.14.4) with ESMTP id q1RKeVaY014092 for ; Mon, 27 Feb 2012 15:40:31 -0500 Received: from localhost (r74-192-17-33.bcstcmta01.clsttx.tl.dh.suddenlink.net [74.192.17.33]) by www.bettercgi.com (Postfix) with ESMTPSA id 2894C21025 for ; Mon, 27 Feb 2012 14:40:30 -0600 (CST) Date: Mon, 27 Feb 2012 14:40:29 -0600 From: Ray Morris Message-ID: <20120227144029.49ebea1a@bettercgi.com> In-Reply-To: References: <20120221102932.19eb3218@bettercgi.com> <5dd15783-9200-4ed0-b746-32a812210f77@email.android.com> Mime-Version: 1.0 Content-Transfer-Encoding: 7bit Subject: Re: [linux-lvm] mirror_region_size default: 4096 six times faster than 512? Reply-To: LVM general discussion and development List-Id: LVM general discussion and development List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , List-Id: Content-Type: text/plain; charset="us-ascii" To: LVM general discussion and development > copying chunks of a few MBs seems to always beat copying > > bytes or KB per chunk. > What kind of RAID? Anything that involves parity is going to require > small writes to read and merge the new data into blocks and rewrite > the parity. At least mdadm RAID1 and RAID5. Hardware raid5 was slow with 512, but not yet tested with 4096 or higher. I'll test it in a few days after a migration completes. -- Ray Morris support@bettercgi.com Strongbox - The next generation in site security: http://www.bettercgi.com/strongbox/ Throttlebox - Intelligent Bandwidth Control http://www.bettercgi.com/throttlebox/ Strongbox / Throttlebox affiliate program: http://www.bettercgi.com/affiliates/user/register.php On Fri, 24 Feb 2012 09:57:30 -0600 Les Mikesell wrote: > On Thu, Feb 23, 2012 at 10:46 AM, Ray Morris > wrote: > > 512 byte sector consumer SATA drives from Seagate and Hitachi. > > Drives attached to a 9560 RAID card exhibited more difference than > > drives in a different system attached to the motherboard directly. > > As I mentioned, I haven't done extensive or highly scientific > > testing, but in general, across various hardware using various > > software, copying chinks of a few MBs seems to always beat copying > > bytes or KB per chunk. > > > What kind of RAID? Anything that involves parity is going to require > small writes to read and merge the new data into blocks and rewrite > the parity. >