Re: [linux-lvm] inactive PV associated to unknown VG

[Heinz Mauelshagen <Mauelshagen@redhat.com>]

On Thu, Feb 19, 2004 at 09:00:03PM -0800, Randy Rubins wrote:
> Thanks, Heinz!
> 
> I got impatient this morning and executed:
> dd if=/dev/zero of=/dev/sdb bs=1 count=1
> 
> hoping the result would be that /dev/sdb1 would
> contain the only valid VG descriptor, and it worked.
> 
> Just for confirmation,
> 
> 1) Does VG always get written at the beginning of PE
> (first 128 bytes), whether it's the whole disk
> (/dev/sdb) or a partition (/dev/sdb1)? 

The LVM1 metadata starts at the very beginning of the device used as a PV.
If you use the whole disk /dev/sdb (which you did before) it starts at
the frist sector of thw disk, with /dev/sdb1 at the first sector of
that partition.

> 
> 2) I was expecting kickstart to clear the disk label,
> but looking at my ks.cfg I only see
> clearpart --all
> It probably should have said:
> clearpart --all --initlabel
> to avoid the situation of having an "old" PV structure
> info on /dev/sdb...  I haven't tried it yet but would
> that have been the right approach?

Yes.

> 
> 3) AJ Lewis's LVM-HOWTO contains a statement:
> "The recommended method of partitioning a disk is to
> create a single partition that covers the whole disk.
> This avoids any nasty accidents with whole disk drive
> device nodes and prevents the kernel warning about
> unknown partition types at boot-up."
> 
> Is there a general agreement amongst lvm developers
> and users that the partition based PE (/dev/sdb1) is
> preferred over the "partitionless" PE (/dev/sdb) in a
> "normal" production environment when the intent is to
> use the entire physical disk as a PE?

It is the recommended approach to avoid the mentioned hassle.
Using one partition which covers the whole disk does only
waste a tiny amount of space vs. the whole disk PV _but_
makes the PV *visible* in the partitioning tools.

Regards,
Heinz    -- The LVM Guy --

> 
> Cheers,
> Randy
> 
> --------------------------------------------------------------------------------
> 
> From: Heinz Mauelshagen <mauelshagen redhat com> 
> To: linux-lvm redhat com 
> Subject: Re: [linux-lvm] inactive PV associated to
> unknown VG 
> Date: Thu Feb 19 10:38:31 2004 
> 
> --------------------------------------------------------------------------------
> 
> Randy,
> 
> the PV structure on /dev/sdb hasn't been removed.
> Overwrite the first 128 bytes of /dev/sdb and rerun
> vgscan.
> 
> 
> On Wed, Feb 18, 2004 at 03:56:56PM -0800, Randy Rubins
> wrote:
> > I'm having a problem importing a VG after
> > re-installing the server (original OS version RH
> 7.3,
> > new RHEL 3 AS).  LVM is picking up the /dev/sdb, as
> > well as the new /dev/sdb1 PV.  Any way to tell LVM
> to
> > ignore /dev/sdb and force it to use /dev/sdb1?  
> > BTW, the LVM version used on RH 7.3 was 0.9.1_beta7,
> > the new LVM version - whatever comes with RHEL 3 AS
> > update 1.
> 
> 1.0.3
> 
> > 
> > Thanks,
> > Randy
> > 
> > pvscan -- reading all physical volumes (this may
> take
> > a while...)
> > pvscan -- ACTIVE   PV "/dev/sda2" of VG "rootvg" 
> > [16.45 GB / 4.69 GB free]
> > pvscan -- inactive PV "/dev/sdb"   is associated to
> > unknown VG "localvg" (run vgscan)
> > pvscan -- inactive PV "/dev/sdb1"  is associated to
> > unknown VG "localvg" (run vgscan)
> > pvscan -- total: 3 [45.42 GB] / in use: 3 [45.42 GB]
> /
> > in no VG: 0 [0]
> > 
> > =====
> > Randy Rubins (eBay ID: lv_hockey)
> > mailto://lv_hockey yahoo com
> > 
> > __________________________________
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> > 
> > _______________________________________________
> > linux-lvm mailing list
> > linux-lvm redhat com
> > https://www.redhat.com/mailman/listinfo/linux-lvm
> > read the LVM HOW-TO at
> http://tldp.org/HOWTO/LVM-HOWTO/
> 
> -- 
> 
> Regards,
> Heinz    -- The LVM Guy --
> 
> *** Software bugs are stupid.
>     Nevertheless it needs not so stupid people to
> solve them ***
> =====
> Randy Rubins (eBay ID: lv_hockey)
> mailto://lv_hockey@yahoo.com
> 
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*** Software bugs are stupid.
    Nevertheless it needs not so stupid people to solve them ***

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Heinz Mauelshagen                                 Red Hat GmbH
Consulting Development Engineer                   Am Sonnenhang 11
                                                  56242 Marienrachdorf
                                                  Germany
Mauelshagen@RedHat.com                            +49 2626 141200
                                                       FAX 924446
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