From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from mx1.redhat.com (ext-mx07.extmail.prod.ext.phx2.redhat.com [10.5.110.31]) by int-mx09.intmail.prod.int.phx2.redhat.com (8.14.4/8.14.4) with ESMTP id t8EIk4CJ007864 (version=TLSv1/SSLv3 cipher=DHE-RSA-AES256-GCM-SHA384 bits=256 verify=NO) for ; Mon, 14 Sep 2015 14:46:04 -0400 Received: from mail.windriver.com (mail.windriver.com [147.11.1.11]) by mx1.redhat.com (Postfix) with ESMTPS id 2E714C0B200C for ; Mon, 14 Sep 2015 18:46:03 +0000 (UTC) Received: from ALA-HCA.corp.ad.wrs.com (ala-hca.corp.ad.wrs.com [147.11.189.40]) by mail.windriver.com (8.15.2/8.15.1) with ESMTPS id t8EIk2DX022531 (version=TLSv1 cipher=AES128-SHA bits=128 verify=FAIL) for ; Mon, 14 Sep 2015 11:46:02 -0700 (PDT) Message-ID: <55F715E8.6010208@windriver.com> Date: Mon, 14 Sep 2015 12:46:00 -0600 From: Chris Friesen MIME-Version: 1.0 References: <55F70C58.5010205@windriver.com> In-Reply-To: <55F70C58.5010205@windriver.com> Content-Transfer-Encoding: 7bit Subject: Re: [linux-lvm] Any way to speed up activation of volumes with snapshots? 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: linux-lvm@redhat.com My apologies, I got the version wrong. The tests below were actually from the 3.4 kernel and LVM 2.2.95. I'm doing tests on the newer versions now. Chris On 09/14/2015 12:05 PM, Chris Friesen wrote: > Hi, > > I'm running a 3.10 kernel with LVM 2.02.95. > > I'm running into a problem where activating snapshots can take quite a long > time, roughly one minute per 25GB of delta between the snapshot and the origin > volume. (See below for my test procedure.) > > I realize that my kernel/LVM aren't exactly bleeding edge, and I wondering > whether more recent versions have done anything to speed up the activation > process (like maybe making it more lazy-loaded rather than reading in a bunch of > data up-front). > > If anyone is aware of such improvements, I'd appreciate it if you could point me > at the appropriate changes. > > > For those that are interested, the test that I did was as follows: > > lvcreate -L100G -n test1 vg > lvcreate -L 100G -s -n test1snapshot /dev/vg/test1 > dd if=/dev/zero of=/dev/cinder-volumes/test1snapshot bs=1M count=95000 > lvchange -an /dev/cinder-volumes/test1snapshot > time lvchange -ay /dev/cinder-volumes/test1snapshot > > The final "lvchange" command took about 4m22s. This works out to 362MB/sec, > which is almost exactly the speed I got doing a "dd" from the volume to /dev/null. > > Thanks, > Chris > > _______________________________________________ > linux-lvm mailing list > linux-lvm@redhat.com > https://www.redhat.com/mailman/listinfo/linux-lvm > read the LVM HOW-TO at http://tldp.org/HOWTO/LVM-HOWTO/