[linux-lvm] vgscan vs vgcfgrestore
mauelshagen at redhat.com
Mon Aug 23 13:42:53 UTC 2004
On Tue, Aug 17, 2004 at 10:53:48PM -0400, Rob Schwartz wrote:
> Hello Heinz,
> Forgive me for writing in English. As I come from the United States I am embarassingly uni-lingual. I have been working with LVM for several months now and finally have had the opportunity to get into the guts of the lvm configuration. I am preparing myself for the situation where my LVM environment gets corrupted in some manner. Actually, last week I encountered a problem with LVM and was unable to quickly recover so I ended up simply rebuilding the LVM PV's, VG's and LV's and restoring data. Fortunately, it was an easy restore. I have been comparing the vgscan utility with vgcfgrestore. In a test environment I have deleted the /etc/lvm* stuff and even deleted the /dev/lvm* stuff and successfully recovered the VG and LV by simply doing a vgscan.
Yes, vgscan's task is to discover any PVs, retrieve the LVM metadata, store
it in /etc/lvmtab* and created devnodes for access to the VGs/LVs.
> Whew... nice... I understand vgcfgbackup and vgcfgrestore but am not sure when I would need to use the configuration backup. The VGDA as I understand it is stored on the PV's. If I have the PV's intact I therefore have the VGDA and hence am able to recover using vgscan. When would I need to use vgcfgrestore?
You indirectly answered your onw question ;)
You need vgcfgrestor, when the metadata on the PVs is *not* intact (eg,
accidential overwrite or starnge crash). and vgscan fails to discover
> I have found much information on LVM on the web but nothing that really pinpoints my question. If there is something out there that I can refer to, please tell me.
Have you referenced the LVM-HOWTO yet (URL below) ?
> linux-lvm mailing list
> linux-lvm at redhat.com
> read the LVM HOW-TO at http://tldp.org/HOWTO/LVM-HOWTO/
Heinz -- The LVM Guy --
*** Software bugs are stupid.
Nevertheless it needs not so stupid people to solve them ***
Heinz Mauelshagen Red Hat GmbH
Consulting Development Engineer Am Sonnenhang 11
Mauelshagen at RedHat.com +49 2626 141200
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