kvm虚拟机默认使用raw格式的镜像格式，性能最好，速度最快，它的缺点就是不支持一些新的功能，如支持镜像,zlib磁盘压缩,AES加密等。 要使用镜像功能，磁盘格式必须为qcow2。下面开始kvm虚拟机快照备份的过程
1，查看现有磁盘镜像格式与转换
（1）查看现有磁盘的格式
[root@KVM test]# qemu-img info hadoop3.img p_w_picpath: hadoop3.img file format: raw virtual size: 10G (10737418240 bytes) disk size: 877M
把raw格式转换成qcow2格式
（2）关闭需要转换磁盘的虚拟机
[root@KVM test]# virsh destroy hadoop3 Domain hadoop3 destroyed [root@KVM test]# virsh list --all Id Name State ---------------------------------------------------- 1 win7 running 6 hadoop2 running - hadoop1 shut off - hadoop3 shut off - hadoop4 shut off
（3）转换磁盘的格式
[root@KVM test]# qemu-img convert -f raw -O qcow2 hadoop3.img hadoop3.qcow2
-f 源镜像的格式
-o 目标镜像的格式
查看转换后的格式，已经转换成了qcow2, 这里是拷贝一份，并将格式转成qcow2
[root@KVM test]# qemu-img convert -f raw -O qcow2 hadoop3.img hadoop3.qcow2 [root@KVM test]# ll total 14975352 -rwxr-xr-x 1 root root 10737418240 Feb 4 14:38 hadoop1.img -rwxr-xr-x 1 qemu qemu 10737418240 Feb 4 16:51 hadoop2.img -rwxr-xr-x 1 root root 10737418240 Feb 4 16:48 hadoop3.img -rw-r--r-- 1 root root 923926528 Feb 4 16:51 hadoop3.qcow2 -rwxr-xr-x 1 root root 10737418240 Feb 4 15:11 hadoop4.img -rwxr-xr-x 1 qemu qemu 8589934592 Feb 2 15:03 win7.img [root@KVM test]# qemu-img info hadoop3.qcow2 p_w_picpath: hadoop3.qcow2 file format: qcow2 virtual size: 10G (10737418240 bytes) disk size: 881M cluster_size: 65536
2，修改虚拟机配置文件
[root@KVM qemu]# virsh edit hadoop3
<domain type='qemu'>
<name>hadoop3</name>
<uuid>586b3cae-943f-e283-d8e7-ed72b01bfa34</uuid>
<memory unit='KiB'>1048576</memory>
<currentMemory unit='KiB'>1048576</currentMemory>
<vcpu placement='static'>1</vcpu>
<os>
<type arch='x86_64' machine='rhel6.6.0'>hvm</type>
<boot dev='hd'/>
</os>
<features>
<acpi/>
<apic/>
<pae/>
</features>
<clock offset='localtime'/>
<on_poweroff>destroy</on_poweroff>
<on_reboot>restart</on_reboot>
<on_crash>restart</on_crash>
<devices>
<emulator>/usr/libexec/qemu-kvm</emulator>
<disk type='file' device='disk'>
<driver name='qemu' type='qcow2' cache='none'/>
<source file='/p_w_picpaths/test/hadoop3.qcow2'/>
<target dev='hda' bus='ide'/>
3，对虚拟机进行快照管理
(1)对hadoop3虚拟机创建快照
[root@KVM qemu]# virsh snapshot-create hadoop3 Domain snapshot 1454577228 created
（2）查看虚拟机快照的版本
[root@KVM qemu]# virsh snapshot-list hadoop3 Name Creation Time State ------------------------------------------------------------ 1454577228 2016-02-04 17:13:48 +0800 shutoff
（3）查看当前虚拟机镜像快照的版本
[root@KVM qemu]# virsh snapshot-current hadoop3 <domainsnapshot> <name>1454577442</name> <state>shutoff</state> <parent> <name>1454577228</name> </parent> <creationTime>1454577442</creationTime> <memory snapshot='no'/> <disks> <disk name='hda' snapshot='internal'/> <disk name='hdc' snapshot='no'/> </disks> <domain type='qemu'> <name>hadoop3</name> <uuid>586b3cae-943f-e283-d8e7-ed72b01bfa34</uuid> <memory unit='KiB'>1048576</memory> <currentMemory unit='KiB'>1048576</currentMemory> <vcpu placement='static'>1</vcpu> <os> <type arch='x86_64' machine='rhel6.6.0'>hvm</type> <boot dev='hd'/> </os> <features> <acpi/> <apic/> <pae/> </features> <clock offset='localtime'/> <on_poweroff>destroy</on_poweroff> <on_reboot>restart</on_reboot> <on_crash>restart</on_crash> <devices> <emulator>/usr/libexec/qemu-kvm</emulator> <disk type='file' device='disk'> <driver name='qemu' type='qcow2' cache='none'/> <source file='/p_w_picpaths/test/hadoop3.qcow2'/> <target dev='hda' bus='ide'/> <address type='drive' controller='0' bus='0' target='0' unit='0'/> </disk> <disk type='block' device='cdrom'> <driver name='qemu' type='raw'/> <target dev='hdc' bus='ide'/> <readonly/> <address type='drive' controller='0' bus='1' target='0' unit='0'/> </disk> <controller type='usb' index='0' model='ich9-ehci1'> <address type='pci' domain='0x0000' bus='0x00' slot='0x04' function='0x7'/> </controller> <controller type='usb' index='0' model='ich9-uhci1'> <master startport='0'/> <address type='pci' domain='0x0000' bus='0x00' slot='0x04' function='0x0' multifunction='on'/> </controller> <controller type='usb' index='0' model='ich9-uhci2'> <master startport='2'/> <address type='pci' domain='0x0000' bus='0x00' slot='0x04' function='0x1'/> </controller> <controller type='usb' index='0' model='ich9-uhci3'> <master startport='4'/> <address type='pci' domain='0x0000' bus='0x00' slot='0x04' function='0x2'/> </controller> <controller type='ide' index='0'> <address type='pci' domain='0x0000' bus='0x00' slot='0x01' function='0x1'/> </controller> <interface type='network'> <mac address='52:54:00:fe:f5:a3'/> <source network='default'/> <address type='pci' domain='0x0000' bus='0x00' slot='0x03' function='0x0'/> </interface> <serial type='pty'> <target port='0'/> </serial> <console type='pty'> <target type='serial' port='0'/> </console> <input type='mouse' bus='ps2'/> <graphics type='vnc' port='5913' autoport='no' listen='0.0.0.0'> <listen type='address' address='0.0.0.0'/> </graphics> <video> <model type='cirrus' vram='9216' heads='1'/> <address type='pci' domain='0x0000' bus='0x00' slot='0x02' function='0x0'/> </video> <memballoon model='virtio'> <address type='pci' domain='0x0000' bus='0x00' slot='0x05' function='0x0'/> </memballoon> </devices> </domain> </domainsnapshot>
（4)查看当前虚拟机镜像文件，快照文件的路径在/var/lib/libvirt/qemu/snapshot/ 下
[root@KVM qemu]# ll /var/lib/libvirt/qemu/snapshot/hadoop3/ total 8 -rw------- 1 root root 3402 Feb 4 17:17 1454577228.xml -rw------- 1 root root 3453 Feb 4 17:17 1454577442.xml
4，恢复虚拟机快照
（1）恢复虚拟机快照必须关闭虚拟机
[root@KVM qemu]# virsh list --all Id Name State ---------------------------------------------------- 1 win7 running 6 hadoop2 running - hadoop1 shut off - hadoop3 shut off - hadoop4 shut off
（2）确认恢复快照的时间，这里是恢复到1454577442
[root@KVM qemu]# virsh snapshot-list hadoop3 Name Creation Time State ------------------------------------------------------------ 1454577228 2016-02-04 17:13:48 +0800 shutoff 1454577442 2016-02-04 17:17:22 +0800 shutoff
（3）执行恢复，并确认恢复版本
[root@KVM qemu]# virsh snapshot-revert hadoop3 1454577442 [root@KVM qemu]# virsh snapshot-current hadoop3
5，删除虚拟机快照
（1）查看虚拟机快照
[root@KVM test]# qemu-img info hadoop3.qcow2 p_w_picpath: hadoop3.qcow2 file format: qcow2 virtual size: 10G (10737418240 bytes) disk size: 881M cluster_size: 65536 Snapshot list: ID TAG VM SIZE DATE VM CLOCK 1 1454577228 0 2016-02-04 17:13:48 00:00:00.000 2 1454577442 0 2016-02-04 17:17:22 00:00:00.000
(2)删除快照
[root@KVM test]# virsh snapshot-delete hadoop3 1454577228 Domain snapshot 1454577228 deleted [root@KVM test]# qemu-img info hadoop3.qcow2 p_w_picpath: hadoop3.qcow2 file format: qcow2 virtual size: 10G (10737418240 bytes) disk size: 881M cluster_size: 65536 Snapshot list: ID TAG VM SIZE DATE VM CLOCK 2 1454577442 0 2016-02-04 17:17:22 00:00:00.000
至此虚拟机快照从创建，查看，删除。如果有报错，再一一的进行拍错。
