1.查看kvm镜像的格式信息
[root@localhost kvm_a]# qemu-img info kvm_a.qcow2
image: kvm_a.qcow2
file format: qcow2
virtual size: 200G (214748364800 bytes)
disk size: 88G
cluster_size: 65536
2、给镜像增加100G空间
[root@localhost kvm_a]# qemu-img resize kvm_a.qcow2 +100G
Image resized.
[root@localhost kvm_a]# qemu-img info kvm_a.qcow2
image: kvm_a.qcow2
file format: qcow2
virtual size: 300G (322122547200 bytes)
disk size: 88G
cluster_size: 65536
3、给镜像减少100G空间 , qcow2格式降低空间
[root@localhost kvm_a]# qemu-img resize kvm_a.qcow2 -100G
This image format does not support resize
由于qcow2格式不支持空间减少，所以要使用raw格式。
[root@localhost kvm_a]# qemu-img convert -O raw kvm_a.qcow2 kvm_a.qcow2
查看镜像信息
[root@localhost kvm_a]# qemu-img info kvm_a.qcow2
image: kvm_a.qcow2
file format: raw
virtual size: 300G (429496729600 bytes)
disk size: 88G
[root@localhost kvm_a]# qemu-img resize kvm_a.qcow2 -100G
Image resized.
[root@localhost kvm_a]# qemu-img info kvm_a.qcow2
image: kvm_a.qcow2
file format: raw
virtual size: 200G (214748364800 bytes)
disk size: 88G
转换为qcow2
[root@localhost kvm_a# qemu-img convert -O qcow2 kvm_a.qcow2 kvm_a.qcow2
[root@localhost kvm_a]# qemu-img info kvm_a.qcow2
image: kvm_a.qcow2
file format: qcow2
virtual size: 200G (214748364800 bytes)
disk size: 88G
