How to mount a xen image ?

1. First you need to find out the partitions and the startsector of partitions:

[root@xen rruban]# file rheltest.img
rheltest.img: x86 boot sector, GRand Unified Bootloader (0.94); 
partition 1: ID=0x83, active, starthead 1, startsector 63, 208782 sectors; 
partition 2: ID=0x8e, starthead 0, startsector 208845, 3871665 sectors, code offset 0x48

There are 3 partitions inside the image file. The startsector of each partition is also listed. Boot partition will have start sector 63.

2. Now you need to get the sector size:

[root@xen]fdisk -lu rheltest.img

Disk rheltest.img: 0 MB, 0 bytes 255 heads, 63 sectors/track, 0 cylinders, total 0 sectors 
Units = sectors of 1 * 512 = 512 bytes        
Device Boot             Start         End      Blocks   Id  System 
rheltest.img1   *          63      208844      104391   83  Linux 
rheltest.img2          208845     4080509     1935832+  8e  Linux LVM

The above shows the sector byte size is 512 byte.

3. To calculating the offset: offset = start_sector x sector_byte_size.

The startsector is 63 for the first partition, therefore the first partition offset is: 63x512=32256

4. Finally, to mount the xen image, use:

mount -o loop,offset=32256  test.img /foldername