[linux-lvm] Disk partition required for LVM?

[linux-lvm] Disk partition required for LVM?

[lvm]

We have been experiencing strange LVM behaviour on multiple
machines. The situation:

 - Debian 3.1 (Sarge)
 - 2.6.8.1 Kernel
 - LVM2
 - 3 IDE disks (2x80GB, 1x120GB) (All Maxtors)

Creating physical volumes is no problem for two disks, but with the
third disk (it is actually on hdb and already a different disk then
the one originally used) problems begin. pvcreate does not give any
errors, but with pvdisplay the disk is not shown while pvscan gives
"Couldn't find device with uuid
'xAMOJ3-xIGd-AJQK-HN5Q-Q9Yg-Mu2D-UYxn0Y'"

It is possible to create volume groups and logical volumes, but
pvscan, vgscan and lvscan keeping failing with the above error.

Neither of the 3 disks has a partition when starting. When on hdb a
partition is created and then hdb1 is used as physical volume
everything works fine.

Why does the partition need to be created on that disk for LVM to work
(and not on the other two)? Is this a problem with LVM2, the 2.6
kernel? Or could it be hardware not functioning as it should,
e.g. disk or controller?

I would like to know why the creation of a partition is necessary. Has
anyone experienced the same problem/behaviour with LVM? If so, is
there a solution so no partition is needed?

Thanks in advance for the help.

Re: [linux-lvm] Disk partition required for LVM?

[Patrick Caulfield]

On Tue, Sep 21, 2004 at 02:32:06PM +0200, lvm@perkamentus.com wrote:
> 
> Why does the partition need to be created on that disk for LVM to work
> (and not on the other two)? Is this a problem with LVM2, the 2.6
> kernel? Or could it be hardware not functioning as it should,
> e.g. disk or controller?
> 
> I would like to know why the creation of a partition is necessary. Has
> anyone experienced the same problem/behaviour with LVM? If so, is
> there a solution so no partition is needed?
> 

Check that you don't have a symlink from /dev/hdb to /dev/cdrom. The debian
lvm.conf file excludes /dev/cdrom from LVM searches.

-- 

patrick

Re: [linux-lvm] Disk partition required for LVM?

[lvm]

On Tue, Sep 21, 2004 at 02:09:26PM +0100, Patrick Caulfield wrote:
> Check that you don't have a symlink from /dev/hdb to /dev/cdrom. The debian
> lvm.conf file excludes /dev/cdrom from LVM searches.

It was indeed the symlink, although not from hdb to cdrom, but from
cdrom to hdb. Removing this symlink (or commenting out the filter
option in lvm.conf) solved the problem.

CDRom has only been present for installation, and afterwards swapped
for extra disk. Symlink however isn't updated.

Another remark: although cdrom are filtered (and thus not allowed for
LVM), no warning/error messages appear. Wouldn't it be useful if LVM
checks this and shows warning/error messages or even exits during
creation?

Re: [linux-lvm] Disk partition required for LVM?

[David Johnston]

On Tue, 2004-09-21 at 09:30, lvm@perkamentus.com wrote:
> On Tue, Sep 21, 2004 at 02:09:26PM +0100, Patrick Caulfield wrote:
> > Check that you don't have a symlink from /dev/hdb to /dev/cdrom. The debian
> > lvm.conf file excludes /dev/cdrom from LVM searches.
> 
> It was indeed the symlink, although not from hdb to cdrom, but from
> cdrom to hdb. Removing this symlink (or commenting out the filter
> option in lvm.conf) solved the problem.
> 
> CDRom has only been present for installation, and afterwards swapped
> for extra disk. Symlink however isn't updated.
> 
> Another remark: although cdrom are filtered (and thus not allowed for
> LVM), no warning/error messages appear. Wouldn't it be useful if LVM
> checks this and shows warning/error messages or even exits during
> creation?

Not really.  Consider users who use multipath; they have to filter or
they'll see the same PV over and over and over again.  A reference in
the docs *would* help, as would a debug message in syslog (debug so it
only shows if we're looking for problems).
-- 
David Johnston <david@littlebald.com>
Little Bald Consulting, LLC