From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from mx1.redhat.com (ext-mx12.extmail.prod.ext.phx2.redhat.com [10.5.110.17]) by int-mx10.intmail.prod.int.phx2.redhat.com (8.14.4/8.14.4) with ESMTP id s8TIGbtK018405 for ; Mon, 29 Sep 2014 14:16:37 -0400 Received: from Ishtar.hs.tlinx.org (ishtar.tlinx.org [173.164.175.65]) by mx1.redhat.com (8.14.4/8.14.4) with ESMTP id s8TIGXqF018466 (version=TLSv1/SSLv3 cipher=DHE-RSA-AES256-GCM-SHA384 bits=256 verify=NO) for ; Mon, 29 Sep 2014 14:16:35 -0400 Message-ID: <5429A1BD.2000206@tlinx.org> Date: Mon, 29 Sep 2014 11:15:25 -0700 From: "Linda A. Walsh" MIME-Version: 1.0 References: <1411839754687039500@businessgrade.com> In-Reply-To: <1411839754687039500@businessgrade.com> Content-Transfer-Encoding: 7bit Subject: Re: [linux-lvm] Why is my LVM Mirror performance so bad? 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"; format="flowed" To: eneal@businessgrade.com, LVM general discussion and development Errol Neal wrote: > Is this just the life of a LVM mirror and the performance here is about as good as it gets? > ---- > It's a bit confusing from what you have above, but *usually*, if you want performance, you set up 1 duplicate device (disk) to duplicate another of the same type. That way when the controller is writing to 1, it will be able to write to the other in the same location and expect *similar* speeds (speeds will vary more on desktop drives vs. enterprise, so overall RAID performance is lost). From what it looks like you have multiple segments mirroring other (parallel?? not sure) segments... but as data is being written to one segment, it also may not have finished writing a parallel copy to another segment. Don't setup multiple segments mirroring each other on 2 devices... have 1 be the mirror of the other and both be of similar type if you want near device speed. i.e. you don't want 4 mirrors, but want to make all of sdb mirror all of sdc.