Qemu-img

External

• RHEL7 Virtualization Administration - Using qemu-img

Internal

• Linux Virtualization Configuration
• Linux Virtualization Operations

Overview

qemu-img is a command-line tool used to create, format, convert, modify and verify virtual machine images offline. It can handle all image formats supported by QEMU.

qemu-img must not be used to modify images in use by a running virtual machine or any other process - this may destroy the image. If an image is queried while it is modified by another process may result in an inconsistent state.

Sub-Commands

info

qemu info <filename>

qemu-img  info /main-storage-pool/testvm-01.img

image: /main-storage-pool/testvm-01.img
file format: qcow2
virtual size: 4.0G (4294967296 bytes)
disk size: 1.3G
cluster_size: 65536
Format specific information:
    compat: 1.1
    lazy refcounts: true

check

Performs a consistency check of the virtual machine image file, if the format is "qcow2", "qed" or "vdi". The command output can be in either "human" or "json" format.

qemu-img check <filename>

snapshot

List the Existent Snapshots

All snapshots present in a disk image can be listed with:

qemu-img snapshot -l <volume-name>

Snapshot list:
ID        TAG                 VM SIZE                DATE       VM CLOCK 
1         appproxy-test-snapshot.qcow2      0 2017-07-04 10:20:45   00:00:00.000

Revert the Disk to a Saved State

The following command applies the snapshot specified by the tag, which means the disk will be reverted to the state specified by the snapshot.

qemu-img snapshot -a <snapshot-tag> <volume-name>

Example:

qemu-img snapshot -a before_the_installation /main-storage-pool/appproxy.qcow2

Delete the Snapshot=

qemu-img snapshot -d <snapshot-tag> <volume-name>