[linux-lvm] LVM configuration question....

[linux-lvm] LVM configuration question....

[Mark J. Bobak]

Hi,

I just installed SuSE 7.2, I have the LVM configured, all storage is on
LVM except for '/'.  It's working great.  All storage is SCSI.  I have one
9GB drive that I did not configure, that I left data I wanted to save.
So, I've copied everything I want from there back on to the new running
system.  Now I want to add this disk to the Volume Group.  So, I deleted
the partitions on it w/ fdisk.  As I could read in the LVM whitepaper,
that's not good enough.  So, I did:

dd if=/dev/zero of=/dev/sdc bs=1k count=1

And that didn't work.  I noticed an (apparent) typo in the the whitepaper,
in that the comment made after the above command is "This command
overwrites the first 10k Bytes of a disk with zeros, deleting any
partition table."  Well, since the command specifies bs=1k and count=1, I
suspect it only overwrites 1k.  So, I tried w/ 'bs=10k count=1', 'bs=1k
count=10', and even 'bs=100k count=1'.  All with the same results.  When I
try to run 'pvcreate', I get:

# pvcreate /dev/sdc
pvcreate -- device "/dev/sdc" has a partition table

pvcreate [-d|--debug] [-f[f]|--force [--force]] [-h|--help] [-y|--yes]
        [-v|--verbose] [-V|--version] PhysicalVolume [PhysicalVolume...]


So, can anyone offer me a clue as to the problem?

Thanks,

-Mark

Re: [linux-lvm] LVM configuration question....

[Goetz Bock]

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On Sun, Jun 24 '01 at 17:30, Mark J. Bobak wrote:
> # pvcreate /dev/sdc
> pvcreate -- device "/dev/sdc" has a partition table
> 
> So, can anyone offer me a clue as to the problem?
Well, you can force pvcreate to use /dev/sdc, but you should not.
use fdisk to make one partition (/dev/sdc1) with the full capacity of
/dev/sdc and make it as LVM (type: 8e). Than use pvcreate /dev/sdc1
(this marks sdc1 as a PV) and add it to the VG as described in the
whitepaper/faq.

    Goetz.

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Re: [linux-lvm] LVM configuration question....

[Mark J. Bobak]

Thanks Goetz.  I'll give it a try!

-Mark

On Sun, 24 Jun 2001, Goetz Bock wrote:

>
> On Sun, Jun 24 '01 at 17:30, Mark J. Bobak wrote:
> > # pvcreate /dev/sdc
> > pvcreate -- device "/dev/sdc" has a partition table
> >
> > So, can anyone offer me a clue as to the problem?
> Well, you can force pvcreate to use /dev/sdc, but you should not.
> use fdisk to make one partition (/dev/sdc1) with the full capacity of
> /dev/sdc and make it as LVM (type: 8e). Than use pvcreate /dev/sdc1
> (this marks sdc1 as a PV) and add it to the VG as described in the
> whitepaper/faq.
>
>     Goetz.
>

Re: [linux-lvm] LVM configuration question....

[Brian J. Murrell]

On Sun, Jun 24, 2001 at 11:48:00PM +0200, Goetz Bock wrote:
> 
> On Sun, Jun 24 '01 at 17:30, Mark J. Bobak wrote:
> > # pvcreate /dev/sdc
> > pvcreate -- device "/dev/sdc" has a partition table
> > 
> > So, can anyone offer me a clue as to the problem?
> Well, you can force pvcreate to use /dev/sdc, but you should not.

Why not?  I thought for non-system (i.e. boot) disks this was
perfectly acceptable.

b.

Re: [linux-lvm] LVM configuration question....

[Goetz Bock]

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On Sun, Jun 24 '01 at 15:32, Brian J. Murrell wrote:
> > Well, you can force pvcreate to use /dev/sdc, but you should not.
> 
> Why not?  I thought for non-system (i.e. boot) disks this was
> perfectly acceptable.
It will gain you about a meg (one cylinder), but will cause all kind of
trouble when you're not very carefyll. lilo, other OSes installers,
user errors can easily cause the rewriting of a MBR. This will kill your
PV, and the VG it belongs to.
Some readers already had this happen, and it was QUITE a pain to recover
the data on the affected VG (I'm not sure if everyone was able to
recover their data, for sure some were (with the help of Heinz IIRC))

    Goetz.

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