实例一 使用qemu-img命令使用快照
kvm环境下qcow2的镜像支持快照
1 确认镜像的格式
[root@nc1 boss]# qemu-img info test.qcow2
image: test.qcow2
file format: qcow2
virtual size: 10G (10737418240 bytes)
disk size: 1.6G
cluster_size: 65536
2 为镜像test.qcow2创建快照，创建快照并没有产生新的镜像，虚拟机镜像大小增加，快照应属于镜像。
[root@nc1 boss]#qemu-img snapshot -c snapshot01 test.qcow2
[root@nc1 boss]#qemu-img snapshot -c snapshot02 test.qcow2
快照名 镜像名
3 列出某个镜像的所有快照
[root@nc1 boss]#qemu-img snapshot -l test.qcow2
Snapshot list:
ID TAG VM SIZE DATE VM CLOCK
1 snapshot01 0 2011-09-07 15:39:25 00:00:00.000
2 snapshot02 0 2011-09-07 15:39:29 00:00:00.000
4 使用快照
[root@nc1 boss]#qemu-img snapshot -a snapshot01 test.qcow2
5 删除快照
[root@nc1 boss]#qemu-img snapshot -d snapshot01 test.qcow2
附：
'snapshot' is the name of the snapshot to create, apply or delete
'-a' applies a snapshot (revert disk to saved state)
'-c' creates a snapshot
'-d' deletes a snapshot
'-l' lists all snapshots in the given image
实例二 利用libvirt使用快照
1 同样先确认镜像的格式为qcow2
[root@nc1 boss]#qemu-img info test.qcow2
image: test.qcow2
file format: qcow2
virtual size: 10G (10737418240 bytes)
disk size: 1.1G
cluster_size: 65536
2 创建并启动以test.qcow2作为镜像的虚拟机,假设虚拟机名称为testsnp，如果虚拟机没有启动，也可创建快照，但是意义不大，快照size为0
开始使用配置文件来创建指定虚拟机的快照
<domainsnapshot>
<name>snapshot02</name> //快照名
<description>Snapshot of OS install and updates</description>//描述
<disks>
<disk name='/home/guodd/boss/test.qcow2'> //虚拟机镜像的绝对路径
</disk>
<disk name='vdb' snapshot='no'/>
</disks>
</domainsnapshot>
保存为snp.xml,开始创建
[root@nc1 boss]#virsh snapshot-create testsnp snp.xml //即以snp.xml作为快照的配置文件为虚拟机testsnp创建快照
Domain snapshot snapshot02 created from 'snp.xml'
3 查看虚拟机testsnp已有的快照
[root@nc1 boss]# virsh snapshot-list testsnp
Name Creation Time State
---------------------------------------------------
1315385065 2011-09-07 16:44:25 +0800 running //1315385065创建时间比snapshot02早
snapshot02 2011-09-07 17:32:38 +0800 running
同样地，也可以通过qemu-img命令来查看快照
[root@nc1 boss]# qemu-img info test.qcow2
image: test.qcow2
file format: qcow2
virtual size: 10G (10737418240 bytes)
disk size: 1.2G
cluster_size: 65536
Snapshot list:
ID TAG VM SIZE DATE VM CLOCK
1 1315385065 149M 2011-09-07 16:44:25 00:00:48.575
2 snapshot02 149M 2011-09-07 17:32:38 00:48:01.341
4 可以通过snapshot-dumpxml命令查询该虚拟机某个快照的详细配置
[root@nc1 boss]# virsh snapshot-dumpxml testsnp 1315385065
<domainsnapshot>
<name>1315385065</name>
<description>Snapshot of OS install and updates</description>
<state>running</state> //虚拟机状态 虚拟机关机状态时创建的快照状态为shutoff（虚拟机运行时创建的快照，即使虚拟机状态为shutoff，快照状态依然为running）
<creationTime>1315385065</creationTime> //虚拟机的创建时间 Readonly 由此可以看出没有给快照指定名称的话，默认以时间值来命名快照
<domain>
<uuid>afbe5fb7-5533-d154-09b6-33c869a05adf</uuid> //此快照所属的虚拟机(uuid)
</domain>
</domainsnapshot>
查看第二个snapshot
[root@nc1 boss]# virsh snapshot-dumpxml testsnp snapshot02
<domainsnapshot>
<name>snapshot02</name>
<description>Snapshot of OS install and updates</description>
<state>running</state>
<parent>
<name>1315385065</name> //当前快照把前一个快照作为parent
</parent>
<creationTime>1315387958</creationTime>
<domain>
<uuid>afbe5fb7-5533-d154-09b6-33c869a05adf</uuid>
</domain>
</domainsnapshot>
5 查看最新的快照信息
[root@nc1 boss]# virsh snapshot-current testsnp
<domainsnapshot>
<name>1315385065</name>
<description>Snapshot of OS install and updates</description>
<state>running</state>
<creationTime>1315385065</creationTime>
<domain>
<uuid>afbe5fb7-5533-d154-09b6-33c869a05adf</uuid>
</domain>
</domainsnapshot>
6 使用快照，指定使用哪一个快照恢复虚拟机
[root@nc1 boss]# virsh snapshot-revert testsnp snapshot02
7 删除指定快照
[root@nc1 boss]# virsh snapshot-delete testsnp snapshot02
Domain snapshot snapshot02 deleted
附：
Snapshot (help keyword 'snapshot')
snapshot-create Create a snapshot from XML
snapshot-create-as Create a snapshot from a set of args
snapshot-current Get the current snapshot
snapshot-delete Delete a domain snapshot
snapshot-dumpxml Dump XML for a domain snapshot
snapshot-list List snapshots for a domain
snapshot-revert Revert a domain to a snapshot
更多详细内容可查看 http://libvirt.org/formatsnapshot.html#SnapshotAttributes