From mboxrd@z Thu Jan 1 00:00:00 1970 From: Tore Anderson Subject: Re: Use LVM on /dev/mapper/diskname and iSCSI Date: Mon, 19 Nov 2007 19:43:59 +0100 Message-ID: <4741D96F.7080502@linpro.no> References: <1195480602.6074.3.camel@sanderbal> <47419854.2000508@linpro.no> <1195484847.6074.16.camel@sanderbal> Reply-To: device-mapper development Mime-Version: 1.0 Content-Type: text/plain; charset=UTF-8; format=flowed Content-Transfer-Encoding: 7bit Return-path: In-Reply-To: <1195484847.6074.16.camel@sanderbal> List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Sender: dm-devel-bounces@redhat.com Errors-To: dm-devel-bounces@redhat.com To: device-mapper development List-Id: dm-devel.ids * S. J. van Harmelen > Thanks for your help! > > I executed the pvs command and it did find a few partitions. I use > iSCSI to share the LUN's to a XenSource server, and XenSource creates > the PV's and LV's in order to provision VM's. Didn't think of that, > but that's on the disk of course. > > Is there any way to configure snapshots for these already created LVM > partitions? Or do I have to whipe the disk clean (rather not do > that, but if I have to it can be done), then create the pv's and lv's > and then share the lv's true iSCSI? > > In that case XenSource will again create pv's and lv's in the shared > lv. Ain't that a problem? You really need a filter line in /etc/lvm/lvm.conf, to keep LVM from claiming 1) individual paths to a dm-multipath controlled LUN, and 2) LUNs that are PVs used by the LVM implementation in your domUs. You don't want LVM to be claiming the paths directly, because you'd no longer have any redundancy - it will override dm-multipath. You also don't want the LVM implementation in your dom0 to be using the same block device as LVM in your domU as physical volumes, as LVM is designed to have exclusive access to its PVs (you might get around this with CLVM, though). Do I understand correctly if you have one LUN that contains your domO (having its file systems in LVs), and several LUNs that contain your domUs, which again are PVs that are supposed to be used by your domU kernels? If so you will want to keep your dom0 from claiming the domU PVs. Use a filter line that accepts only the multipath'ed volume that contains the dom0 installation, and drop the rest. For instance: filter = [ "a|^/dev/mapper/domzero$", "r|.*" ] ...assuming your dom0 data volume is called "domzero" in multipath.conf. Regards -- Tore Anderson