[linux-lvm] How to place LVM2 metadata to other disks which don't belong to any volume group?

[George Brian]

Hi£¬

thank for your reply.

I read about "lvm.conf" and "man pvcreate" and practice like your
instruction.
but it's hard to meet my expection.

I do as follows:
1, setting lvm.conf to dirs
2, pvcreate --pvmetadatacopies 0
3, vgcreate on pv
Aborting vg_write: No metadata areas to write to!

I indeed want to  store metadata in common disk such as /dev/sdb,
eventually to store all vg's metadata to one singe disk which specially
used to store metadata without data.

thanks




2013/12/11 Alasdair G Kergon <agk at redhat.com>

> On Wed, Dec 11, 2013 at 03:06:13PM +0800, George Brian wrote:
> > Instead of storing metadata on PV metadata areas, now I want to store it
> to
> > other disks which don't belong to any volume group, just common disk.
>
> This can indeed be done but because it is not a configuration that receives
> much testing you should check the things you want to do work for you in
> your particular circumstances.
>
> LVM needs to use one 512-byte sector on the device to label it as a PV
> and store its UUID.  By default the 2nd sector is used as this is normally
> free.  Read about --labelsector in 'man pvcreate' and use
> --pvmetadatacopies 0.
>
> Then read about the 'dirs' setting in the 'metadata' section in 'man
> lvm.conf':
>
>         dirs  ¡ª List of directories holding live copies of LVM2 metadata
>         as text files.  These directories must not be  on  logical  vol©\
>         umes.   It  is possible to use LVM2 with a couple of directories
>         here, preferably on different  (non-logical-volume)  filesystems
>         and  with  no  other  on-disk  metadata,  pvmetadatacopies  = 0.
>         Alternatively these directories can be in addition  to  the  on-
>         disk metadata areas.  This feature was created during the devel©\
>         opment of the LVM2 metadata  before  the  new  on-disk  metadata
>         areas  were  designed and no longer gets tested.  It is not sup©\
>         ported under low-memory conditions, and it is important never to
>         edit these metadata files unless you fully understand how things
>         work: to make changes you should always use the tools as normal,
>         or else vgcfgbackup, edit backup, vgcfgrestore.
>
> Alasdair
>
>
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