how to mount a kvm image file

hrmb · 02-07-2010, 07:37 AM

Hi

I am trying to mount a kvm image file (qcow format), I am using this method (http://equivocation.org/node/107), but it doesn't work for me!

please help me, it's urgent

neonsignal · 02-07-2010, 08:06 AM

Can you provide details about where the steps are failing, and what is the error output? Also, what distro are you running?

An alternative method would be to use qemu-img to convert it to a raw image, and then loop mount it (assuming you have the disk space).

hrmb · 02-08-2010, 02:22 AM

Hi,

I am using CentOS 5.4 and the third step dosen't work!!!

Quote:

[root@localhost mnt]# losetup -f
/dev/loop0
[root@localhost mnt]# losetup /dev/loop0 /root/Desktop/kvm-img/win7.img
[root@localhost mnt]# kpartx -av /dev/loop0

the kpartx dosen't show any thing, and furthur steps cause no result.

dev_dks · 02-08-2010, 07:12 AM

Hi,

Instead of using losetup command, Just directly map the image file by using Kpartx command.

Skip losetup step.

Code:

kpartx -av "Path of image file"
 
To Unmap image

kpartx -dv "Path of image file"

Try it, May it will help you.

Dev

dyasny · 02-10-2010, 11:41 AM

This might work with the raw format. For qcow2, if you need to edit the disk, you need to use libguestfs.

Chuck56 · 02-11-2010, 11:06 AM

To the best of my knowledge there is no way to loop mount a qcow or qcow2 disk image. There is a workaround with a raw disk image:

1) Convert your qcow2 to raw

Code:

root@name:/home# qemu-img convert -f qcow2 /home/your_current_image.qcow2 -O raw /home/your_new_image.raw

2) Find your physical hard disk block size:

Code:

root@name:/home# sfdisk -l

Disk /dev/sda: 19457 cylinders, 255 heads, 63 sectors/track
Warning: extended partition does not start at a cylinder boundary.
DOS and Linux will interpret the contents differently.
Units = cylinders of 8225280 bytes, blocks of 1024 bytes, counting from 0

   Device Boot Start     End   #cyls    #blocks   Id  System
/dev/sda1          0+  19456   19457- 156288321    5  Extended
/dev/sda2          0       -       0          0    0  Empty
/dev/sda3          0       -       0          0    0  Empty
/dev/sda4          0       -       0          0    0  Empty
/dev/sda5          0+    243     244-   1959867   82  Linux swap
/dev/sda6   *    244+   1217     974-   7823623+  83  Linux
/dev/sda7       1218+  19456   18239- 146504736   83  Linux

NOTE: This disk shows ", blocks of 1024 bytes,"

3) Issue the mount command with calculated offset:

Code:

root@name:/home# mount -o loop,offset=$((63*1024)) /home/your_new_image.raw /mnt/your_mount_point

or do the math manually: 63 * 1024 = 64512

Code:

root@name:/home# mount -o loop,offset=64512 /home/your_new_image.raw /mnt/your_mount_point

YMMV!