如何挂载一个镜像文件(how to mount an image file)
如何挂载一个镜像文件(how to mount an image file)08/16/2012master4 Comments 在使用KVM或Xen虚拟化的情况下，经常需要使用镜像文件（image file），我们可以将Guest系统启动起来，然后对镜像文件进行修改，不过这样有时也是比较麻烦，其实也是可以将镜像文件直接进行mount的，可以用如下两种办法。
（本文写的RAW格式镜像文件的挂载；我的另一篇文章写了“如何挂载qcow2格式的镜像文件”）
方法一：找出分区开始的开始位置，使用mount命令的offset参数偏移掉前面不需要的，即可得到真正的分区。其具体步骤如下：
1. 用“fdisk -lu my.img”查询image信息；
2. 计算image内分区开始的地方（计算offset），用从N号sector（扇区）开始，则offset=N*M （M为一个sector的大小，一般为512）
3. 使用mount命令挂载为loop设备即可。（如LVM分区，则会较复杂，请见本文最后的介绍）
在Linux系统上具体操作演示如下：
# fdisk -lu rhel6u2.imgYou must set cylinders.You can do this from the extra functions menu.Disk rhel6u2.img: 0 MB, 0 bytes255 heads, 63 sectors/track, 0 cylinders, total 0 sectorsUnits = sectors of 1 * 512 = 512 bytesSector size (logical/physical): 512 bytes / 512 bytesI/O size (minimum/optimal): 512 bytes / 512 bytesDisk identifier: 0x00048b34Device Boot Start End Blocks IdSystemrhel6u2.img1 * 2048 1026047 512000 83LinuxPartition 1 does not end on cylinder boundary.rhel6u2.img2 1026048 104857599 51915776 8eLinux LVMPartition 2 has different physical/logical endings:phys=(1023, 254, 63) logical=(6527, 21, 22)# echo $((2048*512))1048576# mount -o loop,offset=1048576 rhel6u2.img /media/# cd /media/# lsconfig-2.6.32-220.el6.x86_64 initramfs-3.5.0.img System.map-2.6.32-279.el6.x86_64config-2.6.32-279.el6.x86_64 lost+found System.map-3.5.0efi symvers-2.6.32-220.el6.x86_64.gzvmlinuzgrub symvers-2.6.32-279.el6.x86_64.gzvmlinuz-2.6.32-220.el6.x86_64initramfs-2.6.32-220.el6.x86_64.imgSystem.map vmlinuz-2.6.32-279.el6.x86_64initramfs-2.6.32-279.el6.x86_64.imgSystem.map-2.6.32-220.el6.x86_64vmlinuz-3.5.0# echo $((1026048*512))525336576# umount /media# cd /home/image/# umount /media# mount -o loop,offset=525336576 rhel6u2.img /media/mount: unknown filesystem type 'LVM2_member'（镜像文件中的LVM分区mount的问题，本文最后单独说明）# fdisk -lu sles11sp2-i386.imgYou must set cylinders.You can do this from the extra functions menu.Disk sles11sp2-i386.img: 0 MB, 0 bytes255 heads, 63 sectors/track, 0 cylinders, total 0 sectorsUnits = sectors of 1 * 512 = 512 bytesSector size (logical/physical): 512 bytes / 512 bytesI/O size (minimum/optimal): 512 bytes / 512 bytesDisk identifier: 0x0002d3beDevice Boot Start End Blocks IdSystemsles11sp2-i386.img1 2048 4208639 2103296 82Linux swap / SolarisPartition 1 does not end on cylinder boundary.sles11sp2-i386.img2 * 4208640 41943039 18867200 83LinuxPartition 2 has different physical/logical endings:phys=(1023, 254, 63) logical=(2610, 212, 34)# echo $((4208640*512))2154823680# mount -o loop,offset=2154823680 sles11sp2-i386.img /media# cd /media/# lsbin devhomelost+foundmntprocsbin srv sysusrbootetclib media optrootselinuxsuccesstmpvar# umount /media/
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# fdisk -lu rhel6u2.img
You must set cylinders.
You can do this from the extra functions menu.
Disk rhel6u2.img: 0 MB, 0 bytes
255 heads, 63 sectors/track, 0 cylinders, total 0 sectors
Units = sectors of 1 * 512 = 512 bytes
Sector size (logical/physical): 512 bytes / 512 bytes
I/O size (minimum/optimal): 512 bytes / 512 bytes
Disk identifier: 0x00048b34
Device Boot Start End Blocks IdSystem
rhel6u2.img1 * 2048 1026047 512000 83Linux
Partition 1 does not end on cylinder boundary.
rhel6u2.img2 1026048 104857599 51915776 8eLinux LVM
Partition 2 has different physical/logical endings:
phys=(1023, 254, 63) logical=(6527, 21, 22)
# echo $((2048*512))
1048576
# mount -o loop,offset=1048576 rhel6u2.img /media/
# cd /media/
# ls
config-2.6.32-220.el6.x86_64 initramfs-3.5.0.img System.map-2.6.32-279.el6.x86_64
config-2.6.32-279.el6.x86_64 lost+found System.map-3.5.0
efi symvers-2.6.32-220.el6.x86_64.gzvmlinuz
grub symvers-2.6.32-279.el6.x86_64.gzvmlinuz-2.6.32-220.el6.x86_64
initramfs-2.6.32-220.el6.x86_64.imgSystem.map vmlinuz-2.6.32-279.el6.x86_64
initramfs-2.6.32-279.el6.x86_64.imgSystem.map-2.6.32-220.el6.x86_64vmlinuz-3.5.0
# echo $((1026048*512))
525336576
# umount /media
# cd /home/image/
# umount /media
# mount -o loop,offset=525336576 rhel6u2.img /media/
mount: unknown filesystem type 'LVM2_member'
（镜像文件中的LVM分区mount的问题，本文最后单独说明）
# fdisk -lu sles11sp2-i386.img
You must set cylinders.
You can do this from the extra functions menu.
Disk sles11sp2-i386.img: 0 MB, 0 bytes
255 heads, 63 sectors/track, 0 cylinders, total 0 sectors
Units = sectors of 1 * 512 = 512 bytes
Sector size (logical/physical): 512 bytes / 512 bytes
I/O size (minimum/optimal): 512 bytes / 512 bytes
Disk identifier: 0x0002d3be
Device Boot Start End Blocks IdSystem
sles11sp2-i386.img1 2048 4208639 2103296 82Linux swap / Solaris
Partition 1 does not end on cylinder boundary.
sles11sp2-i386.img2 * 4208640 41943039 18867200 83Linux
Partition 2 has different physical/logical endings:
phys=(1023, 254, 63) logical=(2610, 212, 34)
# echo $((4208640*512))
2154823680
# mount -o loop,offset=2154823680 sles11sp2-i386.img /media
# cd /media/
# ls
bin devhomelost+foundmntprocsbin srv sysusr
bootetclib media optrootselinuxsuccesstmpvar
# umount /media/ 方法二：用kpartx建立分区映射后，再mount映射后的设备即可，操作实例如下：
# kpartx -av sles11sp2-i386.imgadd map loop3p1 (253:2): 0 4206592 linear /dev/loop3 2048add map loop3p2 (253:3): 0 37734400 linear /dev/loop3 4208640# mount /dev/mapper/loop3p2 /media/# ls /media/bin devhomelost+foundmntprocsbin srv sysusrbootetclib media optrootselinuxsuccesstmpvar# umount /media/# mount /dev/mapper/loop3p1 /media//dev/mapper/loop3p1 looks like swapspace - not mountedmount: you must specify the filesystem type（其中的交换分区，我也还不知道是否可以mount；其实mount交换分区也没意义）（使用完成后，卸载挂载点、删除映射关系即可）# umount /media/# kpartx -d sles11sp2-i386.imgloop deleted : /dev/loop3
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# kpartx -av sles11sp2-i386.img
add map loop3p1 (253:2): 0 4206592 linear /dev/loop3 2048
add map loop3p2 (253:3): 0 37734400 linear /dev/loop3 4208640
# mount /dev/mapper/loop3p2 /media/
# ls /media/
bin devhomelost+foundmntprocsbin srv sysusr
bootetclib media optrootselinuxsuccesstmpvar
# umount /media/
# mount /dev/mapper/loop3p1 /media/
/dev/mapper/loop3p1 looks like swapspace - not mounted
mount: you must specify the filesystem type
（其中的交换分区，我也还不知道是否可以mount；其实mount交换分区也没意义）
（使用完成后，卸载挂载点、删除映射关系即可）
# umount /media/
# kpartx -d sles11sp2-i386.img
loop deleted : /dev/loop3 关于LVM的mount，可以参考文末参考资料中的vpsee的文章（我也是试多次没做成功，才偶然看到这篇文章的），我对镜像文件中LVM分区的mount操作如下供参考。
# fdisk -lu rhel6u2.imgYou must set cylinders.You can do this from the extra functions menu.Disk rhel6u2.img: 0 MB, 0 bytes255 heads, 63 sectors/track, 0 cylinders, total 0 sectorsUnits = sectors of 1 * 512 = 512 bytesSector size (logical/physical): 512 bytes / 512 bytesI/O size (minimum/optimal): 512 bytes / 512 bytesDisk identifier: 0x00048b34Device Boot Start End Blocks IdSystemrhel6u2.img1 * 2048 1026047 512000 83LinuxPartition 1 does not end on cylinder boundary.rhel6u2.img2 1026048 104857599 51915776 8eLinux LVMPartition 2 has different physical/logical endings:phys=(1023, 254, 63) logical=(6527, 21, 22)# echo $((1026048*512))525336576# losetup /dev/loop0 rhel6u2.img -o 525336576# pvscanPV /dev/loop0 VG VolGroup lvm2 Total: 1 / in use: 1 / in no VG: 0 # vgchange -ay VolGroup2 logical volume(s) in volume group "VolGroup" now active# lvsLV VG Attr LSizePool Origin Data%Move Log Copy%Convertlv_root VolGroup -wi-a--- 45.57glv_swap VolGroup -wi-a---3.94g# mount /dev/VolGroup/lv_root /media/# ls /media/bin cgroupetc lib lost+foundmiscnetprocsbin srvtmpvarbootdev homelib64media mnt optrootselinuxsysusr（使用完后的卸载操作，如下）# umount /media/# vgchange -an VolGroup0 logical volume(s) in volume group "VolGroup" now active# losetup -d /dev/loop0
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# fdisk -lu rhel6u2.img
You must set cylinders.
You can do this from the extra functions menu.
Disk rhel6u2.img: 0 MB, 0 bytes
255 heads, 63 sectors/track, 0 cylinders, total 0 sectors
Units = sectors of 1 * 512 = 512 bytes
Sector size (logical/physical): 512 bytes / 512 bytes
I/O size (minimum/optimal): 512 bytes / 512 bytes
Disk identifier: 0x00048b34
Device Boot Start End Blocks IdSystem
rhel6u2.img1 * 2048 1026047 512000 83Linux
Partition 1 does not end on cylinder boundary.
rhel6u2.img2 1026048 104857599 51915776 8eLinux LVM
Partition 2 has different physical/logical endings:
phys=(1023, 254, 63) logical=(6527, 21, 22)
# echo $((1026048*512))
525336576
# losetup /dev/loop0 rhel6u2.img -o 525336576
# pvscan
PV /dev/loop0 VG VolGroup lvm2
Total: 1 / in use: 1 / in no VG: 0
# vgchange -ay VolGroup
2 logical volume(s) in volume group "VolGroup" now active
# lvs
LV VG Attr LSizePool Origin Data%Move Log Copy%Convert
lv_root VolGroup -wi-a--- 45.57g
lv_swap VolGroup -wi-a---3.94g
# mount /dev/VolGroup/lv_root /media/
# ls /media/
bin cgroupetc lib lost+foundmiscnetprocsbin srvtmpvar
bootdev homelib64media mnt optrootselinuxsysusr
（使用完后的卸载操作，如下）
# umount /media/
# vgchange -an VolGroup
0 logical volume(s) in volume group "VolGroup" now active
# losetup -d /dev/loop0 mount LVM 分区的 参考资料：
Related posts:
[*]如何挂载qcow2格式的镜像文件（how to mount a qcow2 image)
[*]Linux挂载NTFS分区：mount unknown filesystem type ‘ntfs’
[*]Ubuntu上的android sdk: ./emulator: No such file or directory
[*]“mount: could not find any free loop device”解决方案
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