From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from mx1.redhat.com (ext-mx16.extmail.prod.ext.phx2.redhat.com [10.5.110.21]) by int-mx09.intmail.prod.int.phx2.redhat.com (8.14.4/8.14.4) with ESMTP id q8S2p7Ma005710 for ; Thu, 27 Sep 2012 22:51:07 -0400 Received: from Ishtar.sc.tlinx.org (ishtar.tlinx.org [173.164.175.65]) by mx1.redhat.com (8.14.4/8.14.4) with ESMTP id q8S2p59J030117 for ; Thu, 27 Sep 2012 22:51:06 -0400 Received: from [192.168.3.12] (Athenae [192.168.3.12]) by Ishtar.sc.tlinx.org (8.14.5/8.14.4/SuSE Linux 0.8) with ESMTP id q8S2p3ME027225 for ; Thu, 27 Sep 2012 19:51:05 -0700 Message-ID: <50651097.2060200@tlinx.org> Date: Thu, 27 Sep 2012 19:51:03 -0700 From: Linda Walsh MIME-Version: 1.0 Content-Transfer-Encoding: 7bit Subject: [linux-lvm] access or interface to list of blocks that have changed via C.O.W.? 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 I'm trying to use snapshots that are active for a day or so to grab differences between successive days for allowing me to display previous versions of files over a month or so... They aren't a replacement for my daily towero'hanoi-backups, but they are a great deal easier to use. The chink in my plan is the time it is taking to do a diff -- not really a fatal chink but annoying. It takes anywhere from 80-100 minutes for rsync to sum up the changes and copy them to a third volume each day. I figured well sheesh, the lvm should already know what sectors are different. If I could combine that info against a inode+blockmap, I might get that diff computation down to under 10 minutes maybe under 5. The contents of the files that are computed as differences by rsync usually take a minute or less to actually copy into final volume -- anywhere between 800Mb - 2.5GB out of a 1TB volume. So I I could shortcut that diff process, might make it practical to do more than one snapshot a day;... Is there some interface for getting at that information or would it have to be written from scratch? Thnks... Linda