From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from mx1.redhat.com (ext-mx12.extmail.prod.ext.phx2.redhat.com [10.5.110.17]) by int-mx02.intmail.prod.int.phx2.redhat.com (8.13.8/8.13.8) with ESMTP id p360GRnA032054 for ; Tue, 5 Apr 2011 20:16:27 -0400 Received: from mailhost.ankh.org (ammut.ankh.org [93.97.41.159]) by mx1.redhat.com (8.14.4/8.14.4) with ESMTP id p360GN1o006134 for ; Tue, 5 Apr 2011 20:16:24 -0400 Received: from anubis.ankh.org ([172.22.128.3]) by mailhost.ankh.org with esmtp (Exim 4.63) (envelope-from ) id 1Q7GQ3-0006XL-7T for linux-lvm@redhat.com; Wed, 06 Apr 2011 01:16:23 +0100 Message-ID: <4D9BB0D4.8050401@ankh.org> Date: Wed, 06 Apr 2011 00:16:20 +0000 From: James Hawtin MIME-Version: 1.0 References: <4D64FF3C.6080602@abpni.co.uk> <4D656817.6060900@gmail.com> <4D6572C0.6070008@abpni.co.uk> <4D65A1A9.1040205@abpni.co.uk> <4D65A839.50107@abpni.co.uk> <4D65A8F5.8040606@abpni.co.uk> <4D6609E4.10800@abpni.co.uk> <4D6671D7.7020301@abpni.co.uk> <4D667743.3010102@abpni.co.uk> <4D9B7715.7090509@abpni.co.uk> <4D9B8015.2060503@abpni.co.uk> <4D9B82C5.3020704@ankh.org> <4D9B8B5A.2070104@abpni.co.uk> <4D9B9AB9.8070202@ankh.org> <4D9B9D48.5010008@abpni.c! o.uk> <4D9BA196.20006@ankh.org> <4D9BA39A.8020008@abpni.co.uk> <4D9BA845.10607@an! kh.org> <4D9BAD26.5010405@abpni.co.uk> In-Reply-To: <4D9BAD26.5010405@abpni.co.uk> 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"; format="flowed" To: LVM general discussion and development On 06/04/2011 00:00, Jonathan Tripathy wrote: > Ok now things are really getting interesting! > > Actually, when I create new customer LVs, I always specify which > volume group I want to add it to. E.g: > > lvcreate -nNewCustomerLV -L20G vg0 Sadly that is just normal... However a volume group could be made up of more than one disk, you can with an option specify which of the disks (pv) to use. Rather than the system select for you. > where vg0 is /dev/vg0 > and vg0 is a volume group which uses an entire physical partition > (Which I guess is called a PV). That is a vg (volume group) not a pv (physical volume). vgdisplay -v pvs pvdisplay --map and you should get the idea. > > Now, if I were to create my snapshots on a seperate vg, eg: > > lvcreate -L 20G -s -n data_snap /dev/vg0/NewCustomerLV /dev/vg1 > > does that mean I never need to use pvchange to "switch off" vg1? And I > never need to zero or create a "hog"? And no leakage will ever occur? No you are confused pvs are created on disk partitions, one or more pvs then make you vg. LVs are created on top of VGs, VGs are created on top of PVs, PVs are created on partitions on block devices or whole block devices. (Ok we shall stop here however blocks devices could be loop back, meta devices like raid 0/1/5 etc hardware/software or real disks however that is not LVM any more.) > >> Do I get cake now? > Only if it's not a lie.... :) I saw the cake but I got none (Portal) James