From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from mx1.redhat.com (ext-mx13.extmail.prod.ext.phx2.redhat.com [10.5.110.18]) by int-mx09.intmail.prod.int.phx2.redhat.com (8.14.4/8.14.4) with ESMTP id r7DL0v69020204 for ; Tue, 13 Aug 2013 17:00:57 -0400 Received: from santino.mail.tiscali.it (santino.mail.tiscali.it [213.205.33.245]) by mx1.redhat.com (8.14.4/8.14.4) with ESMTP id r7DL0td3028825 for ; Tue, 13 Aug 2013 17:00:56 -0400 Received: from localhost (localhost.localdomain [127.0.0.1]) by spambox.assyoma.it (Postfix) with ESMTP id 1DCB8B60 for ; Tue, 13 Aug 2013 23:00:55 +0200 (CEST) Received: from spambox.assyoma.it ([127.0.0.1]) by localhost (spambox.assyoma.it [127.0.0.1]) (amavisd-new, port 10024) with LMTP id eR-5aPT2bY0T for ; Tue, 13 Aug 2013 23:00:54 +0200 (CEST) Received: from ceres.assyoma.it (mail.assyoma.it [1.1.8.246]) by spambox.assyoma.it (Postfix) with ESMTP id 07DA4B53 for ; Tue, 13 Aug 2013 23:00:54 +0200 (CEST) MIME-Version: 1.0 Content-Transfer-Encoding: 7bit Date: Tue, 13 Aug 2013 23:00:53 +0200 From: g.danti@assyoma.it Message-ID: <6dc995dfc593a1d581b7db5c19fb11ea@assyoma.it> Subject: [linux-lvm] Retrieve changed block 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 Hi all, I'm using LVM2 as VM backend and I am very happy with the result. One thing that I feel useful but that I can't figure how to get working is to use snapshots to obtain the list of changed block after the snapshot was taken. To be more clear: - immagine to have a LV called "LV1" - take a snapshot of "LV1" and name it "SNAP1" - now "SNAP1" has a point-in-time image of "LV1", and by reading from it I can go "back in time" to when I issued the snapshot - but how I can get the list of only the changed block between "LV1" and "SNAP1"? Its my understanding that some Ruby/Python scripts can read the COW table and retrieve the list of the changed block, however I am not so inclined to use them on production server. So, we have a method _inside_ the current LVM tools that enable us to retrieve the changed block list? Regards.