[linux-lvm] Question on vgconvert

[linux-lvm] Question on vgconvert

[Steve Keller]

I want to convert from LVM1 to LVM2 using vgconvert on a server.  Is
vgconvert -M2 <vg-name> considered a risky operation?  Should I switch
the server into single-user mode and make a backup before running
vgconvert?

And will vgconvert take a long time?  May PEs be moved on the disk or
is only the meta-data rewritten?

Steve

Re: [linux-lvm] Question on vgconvert

[Zdenek Kabelac]

Dne 12. 06. 19 v 6:18 Steve Keller napsal(a):
> I want to convert from LVM1 to LVM2 using vgconvert on a server.  Is
> vgconvert -M2 <vg-name> considered a risky operation?  Should I switch
> the server into single-user mode and make a backup before running
> vgconvert?
> 
> And will vgconvert take a long time?  May PEs be moved on the disk or
> is only the meta-data rewritten?
> 
Wow :) where you've been hiding for last ~15 years when format V2 exists ;)
V1 is considered obsolete for very looong time and it's been even dropped
from support from version 2.03.

So you need version 2.02.X.

Operation should be instant (it's only metadata rewrite).

AFAIK no PE should be influenced.

Of course it's wise idea to backup header portion of your device
(unsure what sort of metadata you have there - and the test coverage
for this operation likely might need some 'extra care')
But if you will copy 1st. MiB - you can restore back
and report bug if you would find any problem.


Regards

Zdenek

Re: [linux-lvm] Question on vgconvert

[Steve Keller]

Zdenek Kabelac <zkabelac@redhat.com> wrote:

> Wow :) where you've been hiding for last ~15 years when format V2 exists ;)
> V1 is considered obsolete for very looong time and it's been even dropped
> from support from version 2.03.

That server has indeed been set up rougly 15 years ago. And until
now, we had no need to convert or resize the PVs. Now, the machine is
virtualized and we wanted to reduce the disk size to what's actually
needed.

> So you need version 2.02.X.

Fortunately, that is exactly the version Debian stretch still has...

> Operation should be instant (it's only metadata rewrite).
>
> AFAIK no PE should be influenced.

We have done the conversion and it worked like a charm. Also the following
massive reorganization using pvmove worked fine.

Steve