[linux-lvm] Re: Resizing PV

[Heinz J . Mauelshagen]

On Mon, Sep 22, 2003 at 01:48:09PM +0200, Måns Rullgård wrote:
> "Heinz J . Mauelshagen" <mauelshagen at sistina.com> writes:
> 
> >> Is it possible to reduce the size of a PV, freeing some space at the
> >> end?  I can make sure that the end is unused, of course.
> >
> > No such command implemented yet.
> >
> > Hack:
> > you can use LVM2 and change the text format of the metadata by hand
> > before running vgcfgrestore to store it back onto the PVs.
> >
> > If you want to follow this non-supported path, you want to take a
> > copy of the original metadata file in /etc/lvm/backup/ to be able to
> > back out gain.
> 
> I'm already using lvm2.  I noticed the pvresize command, but it just
> says it's not implemented yet.  Any chance it will be some time soon?

We've got higher priority stuff in the works. Probably later this year.

> 
> As for editing the metadata, I'm a little confused about the meaning
> of some fields.  After running vgcfgbackup, I have this in the file:
> 
>         physical_volumes {
> 
>                 pv0 {
>                         id = "eZV4mb-jk4z-pyfm-tGbJ-mBSW-drRT-ZHtgmn"
>                         device = "/dev/discs/disc0/part2"       # Hint only
> 
>                         status = ["ALLOCATABLE"]
>                         pe_start = 65920
>                         pe_count = 1189 # 37.1562 Gigabytes
>                 }
>         }
> 
> What is the meaning of the pe_start field?  If I wanted to reduce the
> size by, say, 1 GB, would it be correct to reduce pe_count by 32, the
> PE size being 32 MB?

pe_start is the sector offset into the device.
Yes, you need to reduce pe_count by 32 making it 1157 and vgcfgrestore.
You need to have recent LVM2 code so that vgcfgrestore updates the pe_count
properly (and of course, the 32 PEs need to be empty).

> 
> -- 
> Måns Rullgård
> mru at users.sf.net
> 
> 
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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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