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Data recovered successfully... RE: [linux-lvm] Volume group not found on restart [resent]



Heinz, thanks for the help recovering the data -- running a 1.1rc2 kernel
and tools, and vgchange -qn -ay "db_vol" I was able to mount the (fs on the)
lv and recover the data.

Having done that, I was, however unable to remove the lv or the vg (the
volume is set as "static" and so lvremove refuses to do its thing, and on
from there ...). So, I fdisked the partition to a linux partition and did a
vgscan and pvscan, which gives me 'pvscan -- ERROR "pv_read(): PV identifier
invalid" reading physical volumes'. But apparently this is just LVM's way of
saying, I've scanned for PVs and found none with a valid identifier: if I
pvcreate a physical volume the message goes away ;) Is there a better way?

I could not replicate the other problem mentioned in my e-mail below; I find
this hard to believe, but since it was early enough, I must have done an
lvremove correctly, but did not properly do the vgreduce before removing the
hdd on which I was putting the snapshots, to create the problem I had.

Thanks again for helping me recover these data, and I look forward to LVM2.
In the meanwhile, I will be patching the XFS cvs kernel to LVM 1.0.4 for
production use.
	Murthy

PS: All three linux boxes here run LVM - one on Mylex raid, one on 3ware
raid, and the third on single scsi and ide disks. Except for system volumes,
LVM allows me to forego partitioning physical volumes; I just put them whole
into a given volumen group and create lvs as necessary. It may not be
superior to the alternative, but it sure sounds cutting-edge compared to
having a "DOS partition table" floating around - how OLD is that :-)
	SMK



> -----Original Message-----
> From: Heinz J . Mauelshagen [mailto:mauelshagen sistina com]
> Sent: Friday, May 24, 2002 04:33
> To: linux-lvm sistina com
> Subject: Re: [linux-lvm] Volume group not found on restart [resent]
> 
> 
> On Thu, May 23, 2002 at 03:09:12PM -0400, Murthy Kambhampaty wrote:
> > Heinz, thanks for the response.
> > 
> > > Strange.
> > > If you were able to "lvremove /dev/db_vol/snap_db" it 
> shouldn't be 
> > > visible in the metadata I got from you.
> > > 
> > > But it still is in there and has extents allocated on the 
> > > physical volume
> > > you wanted to remove from the volumegroup "db_vol". Unless 
> > > there was no
> > > extents allocated on physical volume /dev/sda, running 
> > > "vgreduce db_vol /dev/sda" was impossible.
> > > 
> > > The steps needed would have been:
> > > 
> > > - close /dev/db_vol/db_snap by unmounting it
> > > - successfully removing the LV with "lvremove /dev/db_vol_snap"
> > > - reducing the volume group successfully with "vgreduce 
> > > db_vol /dev/sda"
> > > 
> > > To check it:
> > > - vgdisplay -v db_vol # just showing 1 PV in VG "db_vol"
> > > - pvscan              # showing /dev/sda to be an unused PV
> > > 
> > I'm pretty sure I went throught the sequence you describe 
> above, and the
> > pvscan at the end said /dev/sda was in "db_vol. I'll 
> replicate the setup (I
> > have two volumes that are now tmp volumes with filesystems 
> on disk, which
> > I'll convert to two different PVs and go through building 
> up and tearing
> > down the setup I had before) and let you know if I get the 
> same behavior.
> 
> Ok.
> In case you are able to replicate it, I'ld be very interested 
> to find out
> why it happens in order to come up with a fix.
> 
> > 
> > > 
> > > > 
> > > > > > 
> > > > > > So, the preferred course here is to "to change the metadata 
> > > > > in order to get
> > > > > > rid of the gone physical volume", and all will be well. 
> > > > > 
> > > > > So there's cons vs. (temporarly) trying 1.1-rc to quorum 
> > > > > activate db_vol
> > > > > in order to retrieve the data?
> > > > > 
> > > > Only to the extent that your message indicated that LVM 
> > > 1.1-rc2 was unstable
> > > > (BTW, do I only install the userspace tools and retain my 
> > > LVM 1.0.1rc4
> > > > kernel code (or do I have to patch the XFS cvs kernel with 
> > > the LVM 1.1-rc2
> > > > kernel code to implement this alternative?)
> > > 
> > > You can go with just the tools in a temporary location.
> > I tried it (download 1.1-rc2, built the kernel and tools, 
> installed the
> > tools (about which time I got your message), then ran 
> "vgscan; vgchange -qn
> > -ay "db_vol") and got the error message "vgchange -- driver 
> doesn't support
> > volume group quorum!"
> 
> Sorry, my fault :(
> Forgot to mention.
> 
> > 
> > I'll install the patched kernel, and try it. Once I recover 
> the data, I can
> > go back to the stock 2.4.18-xfs kernel, installing the lvm-tools rpm
> > supplied with RH 7.2.
> > 
> > I'll let you know how it goes ... ;)
> 
> Thanks.
> 
> > 	Murthy
> > 
> > 
> > 
> > _______________________________________________
> > 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
> =-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-
> =-=-=-=-=-=-=-=-
> 
> _______________________________________________
> linux-lvm mailing list
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> 



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