Kvm快照：
1、基于lvm的快照
2、kvm自带的快照功能（需要qcow2 磁盘文件才支持快照）
关闭kvm虚拟机：
查看磁盘文件信息：
[root@super67 ~]# qemu-img info /var/lib/libvirt/images/ubuntu16-1.img
image: /var/lib/libvirt/images/ubuntu16-1.img
file format: raw
virtual size: 0 (0 bytes)
disk size: 0
磁盘格式转换：
[root@super67 ~]# qemu-img convert -f raw -O qcow2 /var/lib/libvirt/images/ubuntu16-1.img /var/lib/libvirt/images/ubuntu16-1.qcow2
查看：
[root@super67 ~]# ll /var/lib/libvirt/images
-rw-r--r-- 1 qemu qemu 1485881344 Sep 4 12:47 ubuntu-16.04-desktop-amd64.iso
-rwxr-xr-x 1 root root 107 Sep 4 13:58 ubuntu16-1.img
-rw-r--r-- 1 root root 196608 Sep 4 14:11 ubuntu16-1.qcow2
-rw------- 1 root root 8589934592 Sep 4 10:50 www.linux1.cn.img
[root@super67 ~]# qemu-img info /var/lib/libvirt/images/ubuntu16-1.qcow2
image: /var/lib/libvirt/images/ubuntu16-1.qcow2
file format: qcow2
virtual size: 0 (0 bytes)
disk size: 132K
cluster_size: 65536
编辑ubuntu16-1配置文件：
[root@super67 ~]# virsh edit ubuntu16-1
现在ubuntu16-1虚拟机已经是支持快照的虚拟机了。
接下来进行快照：
[root@super67 ~]# cd /var/lib/libvirt/images
创建快照（名字为ubuntu16-1-copy）
[root@super67 images]# virsh snapshot-create ubuntu16-1
Domain snapshot 1472969993 created
[root@super67 images]# virsh snapshot-create-as ubuntu16-1 ubuntu16-1-copy
Domain snapshot ubuntu16-1-copy created
查看快照版本：
[root@super67 images]# virsh snapshot-list ubuntu16-1
Name Creation Time State
------------------------------------------------------------
1472969993 2016-09-04 14:19:53 +0800 shutoff
ubuntu16-1-copy 2016-09-04 14:20:53 +0800 shutoff
查看当前快照版本：
[root@super67 images]# virsh snapshot-current ubuntu16-1 |grep "<name>"
<name>ubuntu16-1-copy</name>
<name>1472969993</name>
<name>ubuntu16-1</name>
再次创建快照：
[root@super67 images]# virsh snapshot-create-as ubuntu16-1 ubuntu16-1-copy1
Domain snapshot ubuntu16-1-copy1 created
查看当前版本：
[root@super67 images]# virsh snapshot-current ubuntu16-1 |grep "<name>"
<name>ubuntu16-1-copy1</name>
<name>ubuntu16-1-copy</name>
<name>ubuntu16-1</name>
恢复快照（kvm虚拟机要先关机）
[root@super67 images]# virsh snapshot-revert ubuntu16-1 ubuntu16-1-copy
查看版本：
[root@super67 images]# virsh snapshot-current ubuntu16-1 |grep "<name>"
<name>ubuntu16-1-copy</name>
<name>1472969993</name>
<name>ubuntu16-1</name>
查看快照：
[root@super67 ~]# qemu-img info /var/lib/libvirt/images/ubuntu16-1.qcow2
image: /var/lib/libvirt/images/ubuntu16-1.qcow2
file format: qcow2
virtual size: 0 (0 bytes)
disk size: 144K
cluster_size: 65536
Snapshot list:
ID TAG VM SIZE DATE VM CLOCK
1 1472969993 0 2016-09-04 14:19:53 00:00:00.000
2 ubuntu16-1-copy 0 2016-09-04 14:20:53 00:00:00.000
3 ubuntu16-1-copy1 0 2016-09-04 14:25:28 00:00:00.000
删除快照：（用TAG号删）
[root@super67 ~]# virsh snapshot-delete ubuntu16-1 ubuntu16-1-copy1
Domain snapshot ubuntu16-1-copy1 deleted
查看快照：
[root@super67 ~]# qemu-img info /var/lib/libvirt/images/ubuntu16-1.qcow2
image: /var/lib/libvirt/images/ubuntu16-1.qcow2
file format: qcow2
virtual size: 0 (0 bytes)
disk size: 144K
cluster_size: 65536
Snapshot list:
ID TAG VM SIZE DATE VM CLOCK
1 1472969993 0 2016-09-04 14:19:53 00:00:00.000
2 ubuntu16-1-copy 0 2016-09-04 14:20:53 00:00:00.000