Accessing a LVM partion inside a Guest OS Raw Image

Sometimes its handy to be able to access the contents of a Guest OS image before/without booting it up.

It can be a pain as the kernel doesn't recognize the devices without a few extra commands.

For quick refence here they are:

To mount an LVM partition:

• kpartx -a /var/lib/libvirt/images/CentOSGuest.img
• pvscan
• vgchange -ay vg_centguest
• mount /dev/mapper/vg_centguest-lv_root /mnt

Note: The pvscan is optional, it's useful to allow you to check the group name.

Then to un-mount:

• umount /mnt
• vgchange -an vg_centguest
• kpartx -d /var/lib/libvirt/images/CentGuesst.img

Behind the scenes, this will create a loop device /dev/loop0 so you may want to increase the number of available devices by editing /etc/modules.conf and add the following line:

options loop max_loop=64