From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from mx1.redhat.com (ext-mx04.extmail.prod.ext.phx2.redhat.com [10.5.110.28]) by int-mx13.intmail.prod.int.phx2.redhat.com (8.14.4/8.14.4) with ESMTP id t8EJGtHJ019730 (version=TLSv1/SSLv3 cipher=DHE-RSA-AES256-GCM-SHA384 bits=256 verify=NO) for ; Mon, 14 Sep 2015 15:16:56 -0400 Received: from mail1.windriver.com (mail1.windriver.com [147.11.146.13]) by mx1.redhat.com (Postfix) with ESMTPS id 11D97FA9CE for ; Mon, 14 Sep 2015 19:16:55 +0000 (UTC) Received: from ALA-HCA.corp.ad.wrs.com (ala-hca.corp.ad.wrs.com [147.11.189.40]) by mail1.windriver.com (8.15.2/8.15.1) with ESMTPS id t8EJGsEi020797 (version=TLSv1 cipher=AES128-SHA bits=128 verify=FAIL) for ; Mon, 14 Sep 2015 12:16:54 -0700 (PDT) Message-ID: <55F71D24.9010903@windriver.com> Date: Mon, 14 Sep 2015 13:16:52 -0600 From: Chris Friesen MIME-Version: 1.0 References: <55F70C58.5010205@windriver.com> <55F71650.7070907@redhat.com> In-Reply-To: <55F71650.7070907@redhat.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 On 09/14/2015 12:47 PM, Zdenek Kabelac wrote: > Dne 14.9.2015 v 20:05 Chris Friesen napsal(a): >> 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. > > Hi > > There is NO way to accelerate your existing setup, other then placing delta on > SSD - the format of snapshot was meant to be used 'temporarily' - i.e. until you > take backup of LV - but not for long-term multi-gigabyte case. > > This is major mis-use of this 'snapshot' feature - which repeats over and over... > > If you want to use long-living snapshots - you need to use thin-provisioning, Thanks for the quick response. Presumably we would still have multi-GB of delta between the original volume and the snapshot, so what would make the activation of a thin-provisioned snapshot faster? Is the metadata stored differently? Chris