如果是非lvm格式的，则非常方便，给mount命令传递offset参数即可，例如：
[root@jcwkyl xen-images]# fdisk -lu centos_vm1
last_lba(): I don't know how to handle files with mode 81ed
You must set cylinders.
You can do this from the extra functions menu.
Disk centos_vm1: 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
centos_vm1p1 * 63 208844 104391 83 Linux
centos_vm1p2 208845 4192964 1992060 8e Linux LVM
看到第一个磁盘分区是Linux分区，起始于63扇区，直接mount：
[root@jcwkyl xen-images]# mkdir -p /mnt/disk
[root@jcwkyl xen-images]# mount -o loop,offset=$[63*512] centos_vm1 /mnt/disk/
[root@jcwkyl xen-images]# ls /mnt/disk/
config-2.6.18-92.el5xen lost+found System.map-2.6.18-92.el5xen xen-syms-2.6.18-92.el5
grub message vmlinuz-2.6.18-92.el5xen
initrd-2.6.18-92.el5xen.img symvers-2.6.18-92.el5xen.gz xen.gz-2.6.18-92.el5
显示，这个linux分区是/boot，root文件系统在centos_vm1p2的这块lvm区中，要设法把它mount上来，使用以下方法：
首先找到它的起始偏移，使用fdisk的-u参数在列出磁盘分区的时候以扇区(sector)为单位，否则是以柱面(cylinder)为单位的：
[root@jcwkyl xen-images]# fdisk -lu centos_vm1
last_lba(): I don't know how to handle files with mode 81ed
You must set cylinders.
You can do this from the extra functions menu.
Disk centos_vm1: 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
centos_vm1p1 * 63 208844 104391 83 Linux
centos_vm1p2 208845 4192964 1992060 8e Linux LVM
从上看出lvm分区起始于208845扇区，把这个地址处的分区mount为loop设备：
-f参数表示自动寻找可用的loop设备文件，-o指定偏移量。
[root@jcwkyl xen-images]# losetup -f -o $[208845*512] centos_vm1
[root@jcwkyl xen-images]# losetup -a
/dev/loop0: [0806]:1097730 (centos_vm1), offset 106928640
扫描lvm volumns:
[root@jcwkyl xen-images]# lvm pvscan
PV /dev/loop0 VG VolGroup00 lvm2 [1.88 GB / 0 free]
Total: 1 [1.88 GB] / in use: 1 [1.88 GB] / in no VG: 0 [0 ]
激活lvm volumn:
[root@jcwkyl xen-images]# lvm vgchange -ay
2 logical volume(s) in volume group "VolGroup00" now active
[root@jcwkyl xen-images]# ls /dev/mapper/
control VolGroup00-LogVol00 VolGroup00-LogVol01
[root@jcwkyl xen-images]# lvm lvs
LV VG Attr LSize Origin Snap% Move Log Copy% Convert
LogVol00 VolGroup00 -wi-a- 1.50G
LogVol01 VolGroup00 -wi-a-384.00M
使用：
[root@jcwkyl xen-images]# mount /dev/mapper/VolGroup00-LogVol00 /mnt/usb
[root@jcwkyl xen-images]# ls /mnt/usb
bin dev home lost+found misc opt proc sbin srv tmp var
boot etc lib media mnt poweroff root selinux sys usr
最后，在操作完以后，umount这个设备，然后设置这个lvm volumn为非活动状态：
[root@jcwkyl xen-images]# umount /mnt/usb
[root@jcwkyl xen-images]# lvm vgchange -an
0 logical volume(s) in volume group "VolGroup00" now active
[root@jcwkyl xen-images]# losetup -a
/dev/loop0: [0806]:1097730 (centos_vm1), offset 106928640
[root@jcwkyl xen-images]# losetup -d /dev/loop0
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