DomU filesystem

If you created your DomU guest by exporting the whole disk and not partitions, here is how you access it's file system from Dom0:

# fdisk -luC 1 /dev/vg0/xenmike

Disk /dev/vg0/xenmike: 10.7 GB, 10737418240 bytes
255 heads, 63 sectors/track, 1305 cylinders, total 20971520 sectors
Units = sectors of 1 * 512 = 512 bytes

           Device Boot      Start         End      Blocks   Id  System
/dev/vg0/xenmike1   *          63      208844      104391   83  Linux
/dev/vg0/xenmike2          208845    19904534     9847845   83  Linux
/dev/vg0/xenmike3        19904535    20948759      522112+  82  Linux swap / Solaris

We want to mount second partition. First calculate offset, we take start value for this partition and multiply it by sector size: 512 * 208845 = 106928640

Now we mount it:

# mount -o loop,offset=106928640 /dev/vg0/xenmike -t ext3 /v
# ls -l /v
total 100
drwxr-xr-x  2 root root  4096 Jun 26 04:04 bin
drwxr-xr-x  2 root root  4096 Jun 25 09:53 boot
drwxr-xr-x  2 root root  4096 Jun 25 09:53 dev
drwxr-xr-x 67 root root  4096 Jul 11 13:48 etc
....