openstack image virsual size 10G太大

处理方法如下：

1. You need to convert the qcow2 image to raw
   qemu-img convert -O raw guest.img guest.raw
2. Then resize the raw file
   qemu-img resize guest.raw 3G
3. Then convert it back to qcow2
   qemu-img convert -O qcow2 -o compat=0.10 guest.raw guest.img
4. Then run the guest and resize your file system

原文地址：https://www.cnblogs.com/longchang/p/11557896.html