[Reprint] how to mount an image file in qcow2 format (how to mount a qcow2 image)

Two months ago, I wrote an article "how to mount an image file". At that time, I didn't write the qcow2 mounting method into it. I just wrote a blog post about qcow2, let's talk about the client image in the Mount qcow2 format. Qcow2 is currently the recommended guest image file format for qemu (qemu-KVM). It is widely used in KVM and xen virtualization.
You can use the tool qemu-NBD that comes with qemu to mount a client. The procedure is as follows:
(Qemu-NBD will also get the qemu-NBD tool after the normal qemu is compiled and installed. It seems to be in the "qemu-common" RPM package in fedora .)

1. Check the system's kernel support for the NBD module (NBD: network block device) and load the module NBD., As follows:

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[[email protected] kvm_demo]# grep NBD /boot/config-3.5.0CONFIG_BLK_DEV_NBD=m[[email protected] kvm_demo]# modinfo nbdfilename: /lib/modules/3.5.0/kernel/drivers/block/nbd.kolicense: GPLdescription: Network Block Devicesrcversion: 56F31584CC2EB73E6F1DA69depends:intree: Yvermagic: 3.5.0 SMP mod_unload modversionsparm: nbds_max:number of network block devices to initialize (default: 16) (int)parm: max_part:number of partitions per device (default: 0) (int)parm: debugflags:flags for controlling debug output (int)[[email protected] kvm_demo]# modprobe nbd max_part=16[[email protected] kvm_demo]# lsmod | grep nbdnbd 7593 0

If the current kernel has not compiled the NBD module, you need to re-compile the module (or compile the entire kernel). When compiling the kernel, select "Device Drivers-> Block devices-> network block Device Support" when "make menuconfig" is used to configure the kernel ".

2. Map the qcow2 image to a network block device (NBD)The command is as follows:

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[[Email protected] kvm_demo] # qemu-NBD-C/dev/nbd0 rhel6u3. qcow2 [[email protected] kvm_demo] # ll/dev/nbd0 * # Check BRW-RW ---- 1 root disk 43, 0 Nov 1/dev/nbd0brw-rw ---- 1 root disk 43, 1 Nov 1/dev/nbd0p1brw-rw ---- 1 root disk 43, 2 Nov 1/dev/nbd0p2

The qemu-NBD tool is qemu disk Network block device server. You can run the "qemu-NBD-help" command to view the help information.

3. Just use the partition of the network block device that you just mapped as that of a common block device. The command line is as follows:

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[[Email protected] kvm_demo] # Mount/dev/nbd0p1/mnt/[[email protected] kvm_demo] # cd/mnt/[[email protected] MNT] # lsbin cgroup etc lib lost + found MISC net proc sbin srv tmp varboot Dev home lib64 media MNT opt root SELinux sys USR [[email protected] MNT] # cd root/[[email protected] root] # Touch nbd-test.txt # create a file here to test it, if you use this qcow2 image as the guest, you can also see the modified file.

4. After using the qcow2 image, uninstall the mounted NBD device and remove the association between the qcow2 image and the NBD device.

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123	[[email protected] kvm_demo]# umount /mnt/[[email protected] kvm_demo]# qemu-nbd -d /dev/nbd0/dev/nbd0 disconnected

If your qcow2 file contains LVM partitions, refer to the second half of my blog article below (about LVM partition mounting ):

Http://smilejay.com/2012/08/mount-an-image-file/

For more information about NBD in Linux, see the following webpage:

Http://nbd.sourceforge.net/

 

Source: http://zhumeng8337797.blog.163.com/blog/static/100768914201341755913109/

[Reprint] how to mount an image file in qcow2 format (how to mount a qcow2 image)