From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from mx1.redhat.com (ext-mx05.extmail.prod.ext.phx2.redhat.com [10.5.110.29]) by smtp.corp.redhat.com (Postfix) with ESMTPS id 201CFAACC5 for ; Fri, 7 Apr 2017 09:12:30 +0000 (UTC) Received: from mr003msb.fastweb.it (mr003msb.fastweb.it [85.18.95.87]) by mx1.redhat.com (Postfix) with ESMTP id BE12619CF96 for ; Fri, 7 Apr 2017 09:12:27 +0000 (UTC) MIME-Version: 1.0 Content-Transfer-Encoding: 7bit Date: Fri, 07 Apr 2017 11:12:25 +0200 From: Gionatan Danti In-Reply-To: References: <1438f48b-0a6d-4fb7-92dc-3688251e0a00@assyoma.it> Message-ID: Subject: Re: [linux-lvm] Snapshot behavior on classic LVM vs ThinLVM 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: LVM general discussion and development Cc: Mark Mielke Il 07-04-2017 10:19 Mark Mielke ha scritto: > > I found classic LVM snapshots to suffer terrible performance. I > switched to BTRFS as a result, until LVM thin pools became a real > thing, and I happily switched back. So you are now on lvmthin? Can I ask on what pool/volume/filesystem size? > > I expect this depends on exactly what access patterns you have, how > many accesses will happen during the time the snapshot is held, and > whether you are using spindles or flash. Still, even with some attempt > to be objective and critical... I think I would basically never use > classic LVM snapshots for any purpose, ever. > Sure, but for nightly backups reduced performance should not be a problem. Moreover, increasing snapshot chunk size (eg: from default 4K to 64K) gives much faster write performance. I more concerned about lenghtly snapshot activation due to a big, linear CoW table that must be read completely... -- Danti Gionatan Supporto Tecnico Assyoma S.r.l. - www.assyoma.it email: g.danti@assyoma.it - info@assyoma.it GPG public key ID: FF5F32A8