[linux-lvm] Solution? found backup hexdump of partition's first MB
Heinz J. Mauelshagen
Mauelshagen at sistina.com
Wed May 30 09:33:50 UTC 2001
On Tue, May 29, 2001 at 08:20:30PM +0200, Jens Benecke wrote:
> On Tue, May 29, 2001 at 09:34:36AM +0200, Jens Benecke wrote:
> > On Tue, May 29, 2001 at 01:06:28AM +0200, Jens Benecke wrote:
> > > Hello,
> > > I upgraded to 2.2.4 (0.9.1-beta2) from 2.2.18 (LVM 0.9) and this seems to
> > > have killed one of my PVs. I tried the 0.9 utilities and updated to
> > > 0.9.1-beta7 when I noticed the problems. No change. Booting back to 2.2.18
> > > didn't help, the PV was gone there as well.
> > follow-up:
> > vgcfgrestore doesn't work, because LVM thinks my hdc1 is no PV. Here's the
> > output: (...)
>
> I think I found a way: I have found a hex-dump backup of the first megabyte
> of the disk in - apparently - working order.
>
> So: hdc1 was the broken PV, it's the only partition on hdc, and I have a
> file called hdc-first-MB-hexdump.
>
> Does this help? ;)
Yes, in case it really contains the needed actual copy.
>
> The question is, does this already contain file system data or is this
> still all LVM structure data?
If it is just a MB -> unlikely, because LVM typically reserves more
than that for the VGDA.
*But* to be really sure, run "pvdata -PP" on the hex dump and look
for pe_on_disk.base + pe_on_disk.size. This will give you the
actual end (in 512 byte units) of the metadata in the file and should
be used to dd it back to disk.
> I'm quite sure that the LVM structure didn't
> change since this file was created, only (of course) the data changed on
> the filesystem contained in the one (single) LV on data=(hdc1,hda1).
See above: you *need* to be sure. Hopefully the pvcreate/vgcfgrestore pair
works for you.
>
>
> --
> Jens Benecke /* Nobody will ever see this error message :-) */
> panic("Cannot initialize video hardware\n");
> -- Linux 2.0.38, arch/m68k/atari/atafb.c
> http://www.hitchhikers.de/ - Die kostenlose Mitfahrzentrale für ganz Europa
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--
Regards,
Heinz -- The LVM Guy --
*** Software bugs are stupid.
Nevertheless it needs not so stupid people to solve them ***
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Heinz Mauelshagen Sistina Software Inc.
Senior Consultant/Developer Am Sonnenhang 11
56242 Marienrachdorf
Germany
Mauelshagen at Sistina.com +49 2626 141200
FAX 924446
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