[linux-lvm] lvm partition on ramdisk

Stuart D. Gathman stuart at bmsi.com
Tue May 13 01:29:22 UTC 2008

On Mon, 12 May 2008, Larry Dickson wrote:

> However, let me follow up your (and Stuart's) point. Are you saying that an
> unmounted LVM volume will mess up the boot, even if the volume in question
> is not mapped to boot or /? I was proceeding under the assumption that LVM
> would be happy to sew the pieces together again later, even if the data in
> them is trashed.

As long as the VG is not needed in initrd (e.g. a test VG), you should
be ok.  You will simply have to go through the procedure of removing the
"failed" PV and adding it back after a reboot.  As long as your root fs
(and /usr and other stuff needed at startup) are not on the test VG, you
should be fine.  The problem is that the VG will not activate automatically
with a missing PV.  Even with --partial, it will activate the VG
as readonly metadata.  Yes, AIX handles this better, IMO.  But Linux LVM is
getting there.

For your application, you should make a separate "testvg" VG for your test
that does not have your system.  At boot, activate the VG with --partial, 
then use "pvcreate -u " to set the UUID on the ramdisk to match the UUID
originally on the ramdisk, followed by vgcfgrestore.

	      Stuart D. Gathman <stuart at bmsi.com>
    Business Management Systems Inc.  Phone: 703 591-0911 Fax: 703 591-6154
"Confutatis maledictis, flammis acribus addictis" - background song for
a Microsoft sponsored "Where do you want to go from here?" commercial.

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