Linux – Mount partition on KVM guest and host at the same time

Seems that I finally figured out how to do things I needed. Here is what I did:

# kpartx -av /dev/VolGroup00/kvm101_img
# vgscan

if VolGroup names identical in guest and host systems, then you have to rename guest VolGroup

# vgrename <uuid> VolGroupXX

uuid of VolGroups you can check in vgdisplay. So, the trick is in activating guest VolGroup:

# lvscan
# vgchange -ay VolGroupXX
# lvscan

After that it's easily mounted:

# mount /dev/VolGroupXX/LogVol00 /mnt

Finally, the backward process is:

# umount /mnt
# vgchange -an VolGroupXX
# kpartx -dv /dev/VolGroup00/kvm101_img
# pvscan

The last command cleans the LVM cache and removes the physical volume created by kpartx from LVM.

You need to resize the partition /dev/vda2 as well, as your physical volume resides in a partition. You can use parted to resize the partition online. When you have resized the partition you can resize the pv with pvresize and afterwards the LV with lvextend.

Best,

Falk