1、qcow2格式镜像文件大小问题

正常情况下，通过ls命令看到的qcow2文件大小应该等于disk size

# qemu-img info centos7.7.qcow2
image: centos7.7.qcow2
file format: qcow2
virtual size: 50G (53687091200 bytes)
disk size: 1.5G
cluster_size: 65536
Format specific information:
    compat: 1.1
    lazy refcounts: false

# ls -l -h
total 1.6G
-rw-r--r-- 1 root root 1.6G Jan  3 13:45 centos7.7.qcow2

但是通过Centos 的Virtual Manager创建的虚拟机qcow2镜像大小似乎有点问题
通过ls看到的文件大小和qcow2镜像的virtual size大小差不多

# qemu-img info centos7.7.qcow2
image: centos7.7.qcow2
file format: qcow2
virtual size: 50G (53687091200 bytes)
disk size: 1.6G
cluster_size: 65536
Format specific information:
    compat: 1.1
    lazy refcounts: true

# ls -l
total 1626572
-rw------- 1 root root 53695545344 Jan  3 11:38 centos7.7.qcow2

2、通过qemu-img命令可将qcow2格式镜像文件大小压缩至disk size

# qemu-img convert -O qcow2 centos7.7.qcow2 new.qcow2