[linux-lvm] Resizing PV

[linux-lvm] Resizing PV

[Måns Rullgård]

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.

-- 
M�ns Rullg�rd
mru@users.sf.net

Re: [linux-lvm] Resizing PV

[Heinz J . Mauelshagen]

On Mon, Sep 22, 2003 at 12:21:59PM +0200, Måns Rullgård wrote:
> 
> 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.

> 
> -- 
> Måns Rullgård
> mru@users.sf.net
> 
> 
> _______________________________________________
> linux-lvm mailing list
> linux-lvm@sistina.com
> http://lists.sistina.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 ***

=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-

Heinz Mauelshagen                                 Sistina Software Inc.
Senior Consultant/Developer                       Am Sonnenhang 11
                                                  56242 Marienrachdorf
                                                  Germany
Mauelshagen@Sistina.com                           +49 2626 141200
                                                       FAX 924446
=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-

[linux-lvm] Re: Resizing PV

[Måns Rullgård]

"Heinz J . Mauelshagen" <mauelshagen@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?

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?

-- 
M�ns Rullg�rd
mru@users.sf.net

Re: [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@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@users.sf.net
> 
> 
> _______________________________________________
> linux-lvm mailing list
> linux-lvm@sistina.com
> http://lists.sistina.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 ***

=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-

Heinz Mauelshagen                                 Sistina Software Inc.
Senior Consultant/Developer                       Am Sonnenhang 11
                                                  56242 Marienrachdorf
                                                  Germany
Mauelshagen@Sistina.com                           +49 2626 141200
                                                       FAX 924446
=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-

[linux-lvm] Re: Resizing PV

[Måns Rullgård]

"Heinz J . Mauelshagen" <mauelshagen@sistina.com> writes:

> pe_start is the sector offset into the device.

OK, I thought it might be, but I wasn't sure.

> 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

How recent?  Is this new enough?

  LVM version:     2.00.03 (2003-07-13)
  Library version: 1.00.02-ioctl (2003-07-12)
  Driver version:  4.0.0

I'm using whatever device-mapper is in Linux 2.6.0-test5.

> properly (and of course, the 32 PEs need to be empty).

-- 
M�ns Rullg�rd
mru@users.sf.net

Re: [linux-lvm] Re: Resizing PV

[Heinz J . Mauelshagen]

On Mon, Sep 22, 2003 at 03:12:55PM +0200, Måns Rullgård wrote:
> "Heinz J . Mauelshagen" <mauelshagen@sistina.com> writes:
> 
> > pe_start is the sector offset into the device.
> 
> OK, I thought it might be, but I wasn't sure.
> 
> > 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
> 
> How recent?  Is this new enough?
> 
>   LVM version:     2.00.03 (2003-07-13)
>   Library version: 1.00.02-ioctl (2003-07-12)
>   Driver version:  4.0.0

Should do it.

> 
> I'm using whatever device-mapper is in Linux 2.6.0-test5.

That's ok. device-mapper isn't involved in such
userspace metadata updates to the PVs.

> 
> > properly (and of course, the 32 PEs need to be empty).
> 
> -- 
> Måns Rullgård
> mru@users.sf.net
> 
> 
> _______________________________________________
> linux-lvm mailing list
> linux-lvm@sistina.com
> http://lists.sistina.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 ***

=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-

Heinz Mauelshagen                                 Sistina Software Inc.
Senior Consultant/Developer                       Am Sonnenhang 11
                                                  56242 Marienrachdorf
                                                  Germany
Mauelshagen@Sistina.com                           +49 2626 141200
                                                       FAX 924446
=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-

[linux-lvm] Re: Resizing PV

[Måns Rullgård]

"Heinz J . Mauelshagen" <mauelshagen@sistina.com> writes:

>> > pe_start is the sector offset into the device.
>> 
>> OK, I thought it might be, but I wasn't sure.
>> 
>> > 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
>> 
>> How recent?  Is this new enough?
>> 
>>   LVM version:     2.00.03 (2003-07-13)
>>   Library version: 1.00.02-ioctl (2003-07-12)
>>   Driver version:  4.0.0
>
> Should do it.

It seemed to work.  Thanks for the help.

-- 
M�ns Rullg�rd
mru@users.sf.net