[linux-lvm] Re: Resizing PV

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"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?

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?

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