How to mount Xen Tap Disk in XEN Server
Assume that the tap disk is using xvda
1) losetup /dev/loop0 /vm/xen_xxx/data
where /vm/xen_xxx/data is your xen image
2) Once this is mounted, You can do a fdisk to check the partition inside /dev/loop0
3) kpartx -a /dev/loop0 to reload the partition layout
4) mount /dev/mapper/loop0p1 /mnt to mount the partition into /mnt
Cheers.