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 p1NGDX4g021833 for ; Wed, 23 Feb 2011 11:13:33 -0500 Received: from ps536.phatservers.com (ps536.phatservers.com [216.17.105.202]) by mx1.redhat.com (8.14.4/8.14.4) with ESMTP id p1NGDPsQ012624 for ; Wed, 23 Feb 2011 11:13:25 -0500 Received: from r74-192-17-33.bcstcmta01.clsttx.tl.dh.suddenlink.net ([74.192.17.33] helo=localhost) by ps536.phatservers.com with esmtpa (Exim 4.66) (envelope-from ) id 1PsHKm-0000mY-Fr for linux-lvm@redhat.com; Wed, 23 Feb 2011 08:13:04 -0800 Date: Wed, 23 Feb 2011 10:12:59 -0600 From: Ray Morris Message-ID: <20110223101259.77143753@bettercgi.com> In-Reply-To: <4D651735.1000802@abpni.co.uk> References: <4D64FF3C.6080602@abpni.co.uk> <1298466573.19562.147.camel@ubuntu> <4D65124C.1070505@abpni.co.uk> <1298470564.19562.150.camel@ubuntu> <4D651735.1000802@abpni.co.uk> Mime-Version: 1.0 Content-Transfer-Encoding: 7bit Subject: Re: [linux-lvm] Snapshots and disk re-use 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" To: linux-lvm@redhat.com On 23/02/11 14:16, Joe Thornber wrote: > And how do I zero just exception store? In this example, the normal lv is c1_s1. It has two snapshots, c1_s1_snap0 and c1_s1_snap1. List the underlying volumes like so: [root@clonebox2 ~]# ls -1 /dev/mapper/clones-c1_s1* /dev/mapper/clones-c1_s1 /dev/mapper/clones-c1_s1-real /dev/mapper/clones-c1_s1_snap0 /dev/mapper/clones-c1_s1_snap0-cow /dev/mapper/clones-c1_s1_snap1 /dev/mapper/clones-c1_s1_snap1-cow Half of those would be hidden to lvdisplay, though the man page will probably tell you how to show hidden LVs. "ls" shows them all. c1_s1_snap0-cow and c1_s1_snap1-cow are the copy on write volumes, the exception stores, I believe. -real is where the current data lives, and c1_s1, the "main" LV is a basically a proxy which reads directly from -rela, but diverts writes so that old data is copied to -cow. -snap0 is a proxy which reads from either -cow or -real as needed. Hopefully someone will tell me where I'm wrong, if I am. Zeroing c1_s1 first, then c1_s1_snap0-cow would zero everything, or zeroing -real and -cow would be more efficient because you avoid the copy on write penalty when zeroing the origin. I haven't actually tested this, only reasoned through it. -- Ray Morris support@bettercgi.com Strongbox - The next generation in site security: http://www.bettercgi.com/strongbox/ Throttlebox - Intelligent Bandwidth Control http://www.bettercgi.com/throttlebox/ Strongbox / Throttlebox affiliate program: http://www.bettercgi.com/affiliates/user/register.php On Wed, 23 Feb 2011 14:18:29 +0000 Jonathan Tripathy wrote: > > _______________________________________________ > linux-lvm mailing list > linux-lvm@redhat.com > https://www.redhat.com/mailman/listinfo/linux-lvm > read the LVM HOW-TO at http://tldp.org/HOWTO/LVM-HOWTO/ >