How to mount Oracle VM guest image and fsck it

Jephe Wu - http://linuxtechres.blogspot.com

Objective: modify and fix Oracle VM guest OS image file
Environment: Oracle VM server 3.1.1, Oracle Linux 5.8 64bit OS image


Steps:

1. mount system image as follows

[root@ovms03 db02]# file /OVS/Repositories/0004fb00000300009471703af52bc769/VirtualDisks/0004fb00001200006ff9f87b9279c6dd.img
/OVS/Repositories/0004fb00000300009471703af52bc760/VirtualDisks/0004fb00001200006ff9f87b9279c6dr.img: x86 boot sector; partition 1: ID=0x83, active, starthead 0, startsector 2048, 208896 sectors; partition 2: ID=0x83, starthead 0, startsector 210944, 24954880 sectors, code offset 0x48
Note: there are two partitions inside this image file.

[root@ovms03 db02]#  mount -o offset=$((512*210944)) /OVS/Repositories/0004fb00000300009471703af52bc760/VirtualDisks/0004fb00001200006ff9f87b9279c6dr.img /mnt/a
[root@ovms03 db02]#  mount -o offset=$((512*2048))
/OVS/Repositories/0004fb00000300009471703af52bc760/VirtualDisks/0004fb00001200006ff9f87b9279c6dr.img /mnt/a/boot/

2. chroot to it and modify accordingly
cd /mnt/a
chroot .
chkconfig --list
vi /etc/hosts
umount /mnt/a/boot
umount /mnt/a

3. fsck image file if required.

[root@ovms03 db02]# losetup /dev/loop0 /OVS/Repositories/0004fb00000300009471703af52bc769/VirtualDisks/0004fb00001200006ff9f87b9279c6dr.img -o $((512*210944))
[root@ovms03 goepsdb02]# fsck /dev/loop0
fsck 1.39 (29-May-2006)
e2fsck 1.39 (29-May-2006)
/: clean, 147679/2985984 files, 955713/3119360 blocks

[root@ovms03 goepsdb02]# losetup -d /dev/loop0

4. Other useful commands:

xm create vm.cfg

xm list

xm shutdown id

xm destroy id