[CentOS] Moving LVM from one machine to another

Robert Heller heller at deepsoft.com
Sat Jan 9 04:02:12 UTC 2010

At Fri, 8 Jan 2010 22:40:21 -0500 CentOS mailing list <centos at centos.org> wrote:

> My CentOS4 machine died (CPU cooler failure, causing CPU to die).
> In this machine I had 5 Tbyte disks in a RAID5, and LVM structures
> on that.
> Now I've moved those 5 disks onto a CentOS5 machine and the RAID array
> is being rebuilt.  However the LVM structures weren't detected at boot
> time.  I was able to "vgscan" and 'vgchange -a y' to bring the volume
> online and then fsck the logical volumes.
> But I was concerned this didn't happen at boot time.  Do I need to do
> anything else, or have the commands I've run done sufficient?
> FWIW, this machine has no other LVM (nor RAID) disks on it.

This is why.  Unless the machine 'knows' to look for LVM (eg has the
mumble mumble in /etc/lvm/), it wouldn't look for it during start up.  And
unless it's root file system is on LVM its initrd won't have the
"vgscan" and 'vgchange -a y' commands in the init script.

RAID itself is seen by the kernel if the disks are partitioned with
'Linux RAID Autodetect' partition types.

> (only 5 more hours for the rebuild to complete!)

And hopefully, you won't get a disk error in the those errors and lose
the whole array.

Robert Heller             -- 978-544-6933
Deepwoods Software        -- Download the Model Railroad System
http://www.deepsoft.com/  -- Binaries for Linux and MS-Windows
heller at deepsoft.com       -- http://www.deepsoft.com/ModelRailroadSystem/

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