copying lvm with the same name

[Rick Stevens]

Aldo Foot wrote:
> On Thu, Mar 19, 2009 at 10:17 AM, Rick Stevens <ricks at nerd.com> wrote:
>> Frank Cox wrote:
>>> On Wed, 18 Mar 2009 17:07:28 -0700
>>> Rick Stevens wrote:
>>>
>>>> We have a serious conflict here.  The df command shows you as on sda,
>>>> but LVM is reporting sdb.  My gut reaction is to have you do a:
>>>>
>>>>        vgreduce --test VolGroup00 /dev/sdb2
>>>>
>>>> and see if it would be successful.  If so, then remove the "--test" and
>>>> cross your fingers.
>>> [root at mutt temp]# vgreduce --test VolGroup00 /dev/sdb2
>>>  Test mode: Metadata will NOT be updated.
>>>  Physical Volume "/dev/sdb2" not found in Volume Group "VolGroup00"
>>>
>>> This is consistent with the fact that the "active" Volume Group that I'm
>>> using
>>> is not on /dev/sdb2.  It's just the "lvdisplay -vm" command that shows it
>>> as
>>> being in use.
>> This is truly screwey.  The pvscan shows sdb2 as part of VolGroup00,
>> lvdisplay shows the partition as in use, but vgreduce says sdb2 isn't
>> part of the VG.  Hoo, boy.
>>
>> Frank, this is potentially dangerous, but you can try
>>
>>        # pvremove /dev/sdb2
>>
>> to wipe out sdb2's PV status.  Since you seem to be running on /dev/sda
>> and vgreduce claims that /dev/sdb2 isn't part of the active VG, you
>> should be able to do this without blowing things up.
>>
>> Damn this makes me nervous!
> 
> The pvremove man page does say whether the UUID can be used to remove
> a PV. Using the UUID would've come very handy in this kind of situation.

True, Aldo, but the interesting thing is that we're seeing very
inconsistent data.  The LV is running on /dev/sda2, but the status info
show stuff as being on /dev/sdb2.  For example, vgreduce says that 
/dev/sdb2 isn't part of the VG, while vgdisplay says it is.  lvdisplay
shows extents on /dev/sdb2 as being in use when, in fact, they aren't.

My brain is starting to hurt.
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