From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from mx3.redhat.com (mx3.redhat.com [172.16.48.32]) by int-mx1.corp.redhat.com (8.13.1/8.13.1) with ESMTP id lADHDfa1015506 for ; Tue, 13 Nov 2007 12:13:41 -0500 Received: from mail2.syneticon.net (mail.syneticon.net [213.239.212.131]) by mx3.redhat.com (8.13.1/8.13.1) with ESMTP id lADHDYZw008973 for ; Tue, 13 Nov 2007 12:13:34 -0500 Received: from postfix1.syneticon.net (postfix1.syneticon.net [192.168.112.6]) by mail2.syneticon.net (Postfix) with ESMTP id 390CE3DCA0 for ; Tue, 13 Nov 2007 18:13:27 +0100 (CET) Received: from localhost (filter1.syneticon.net [192.168.113.3]) by postfix1.syneticon.net (Postfix) with ESMTP id B2F92947E for ; Tue, 13 Nov 2007 18:13:27 +0100 (CET) Received: from postfix1.syneticon.net ([192.168.113.4]) by localhost (mx03.syneticon.net [192.168.113.3]) (amavisd-new, port 10025) with ESMTP id FiY-708nNzsY for ; Tue, 13 Nov 2007 18:13:21 +0100 (CET) Received: from [192.168.10.145] (xdsl-87-79-104-215.netcologne.de [87.79.104.215]) by postfix1.syneticon.net (Postfix) with ESMTP for ; Tue, 13 Nov 2007 18:13:21 +0100 (CET) Message-ID: <4739DB30.9060805@wpkg.org> Date: Tue, 13 Nov 2007 18:13:20 +0100 From: Tomasz Chmielewski MIME-Version: 1.0 Content-Transfer-Encoding: 7bit Subject: [linux-lvm] balooning/dynamic 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: LVM general discussion and development Right now, one has to specify a snapshot size. If the snapshot takes more space that one specified with -s (size), that snapshot is automatically dropped, and is no longer usable. Sometimes, it is just not possible to know beforehand how much data will change, but on the other hand, specifying 100% snapshot size is not possible or hard to estimate. Is it possible to make a "balooning", or dynamic LVM snapshot? That is, if the snapshot reaches its maximum, it will be automatically resized, provided we still have space on the medium. Looking at lvm manuals, I didn't see such a feature, and the only possibility seems to be to create a userspace program which would check the status of the snapshots periodically, and resize them if needed - but this seems crude, and may not work sometimes (very loaded system, volumes with a lot of writes etc.). -- Tomasz Chmielewski http://lists.wpkg.org