From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Date: Mon, 28 May 2001 11:20:30 +0000 From: "Heinz J. Mauelshagen" Subject: Re: [linux-lvm] Root on LVM and vgscan Message-ID: <20010528112030.H26710@sistina.com> References: <200105250828.JAA11414@queeg.britain.agilent.com> Mime-Version: 1.0 In-Reply-To: <200105250828.JAA11414@queeg.britain.agilent.com>; from dick@britain.agilent.com on Fri, May 25, 2001 at 09:28:34AM +0100 Sender: linux-lvm-admin@sistina.com Errors-To: linux-lvm-admin@sistina.com Reply-To: linux-lvm@sistina.com List-Help: List-Post: List-Subscribe: , List-Unsubscribe: , List-Archive: List-Id: Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit To: linux-lvm@sistina.com On Fri, May 25, 2001 at 09:28:34AM +0100, Dick Middleton wrote: > I have root running on lvm on sw raid partitions on linux 2.2.18. It all > works fine. However I have had difficulty during booting after adding new > LVs. The symptom is that the initial mounts of LVs fails or the wrong > partition is mounted. > > What happens is that vgscan is run during the initrd phase and so the lvmtab > is updated on the ram disk. Once the root file system on the hard disk has > been mounted the lvmtab on that comes into use. That has not been updated by > vgscan and so does not reflect the changes. > > Obviously it's possible to run vgscan again (between remounting root rw and > checking the other discs) to update the lvmtab but it does beg a few > questions. Yes, that's the option (forcing some overhead). The other would be to get the actual /etc/lvmtab* from the initial ram disk :-) > > 1) why does mount use the data in lvmtab and not in /proc to find out about > active VGs? mount doesn't access /etc/lvmtab* at all. The problem is that minor numbers are not striktly related to logical volumes; they are associated at vgscan time. > > 2) if lvmtab is so essetial why is it not updated by vgcreate/lvcreate and > other utilities when changes are made? See above. > > 3) would it not be possible/better to update lvmtab from /proc without doing > a rescan. That could only be partially done, because /etc/lvmtab* contains the complete metadata whereas /proc doesn't. > > I don't know the issues involved and reasoning behind the design of this > aspect of LVM but it does seem to me that there is something less than ideal > in the current scheme. The virtuall assignement of minor numbers to LVs causes the problem in the root on LVM (and NFS) case. That'l likly be changed anyway. > > Dick > _______________________________________________ > linux-lvm mailing list > linux-lvm@sistina.com > http://lists.sistina.com/mailman/listinfo/linux-lvm > read the LVM HOW-TO at http://www.sistina.com/lvm/Pages/howto.html -- Regards, Heinz -- The LVM Guy -- *** Software bugs are stupid. Nevertheless it needs not so stupid people to solve them *** =-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=- Heinz Mauelshagen Sistina Software Inc. Senior Consultant/Developer Am Sonnenhang 11 56242 Marienrachdorf Germany Mauelshagen@Sistina.com +49 2626 141200 FAX 924446 =-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-