KVM虛擬機快照
下面說說KVM虛擬化的快照功能：
1.快照實際上做的是虛擬機的XML配置文件，默認快照XML文件在/var/lib/libvirt/qemu/snapshot/[vmachine_name]/下
2.快照只支持qcow2磁盤格式的系統
KVM虛擬化快照的實現方式：
kvm快照有兩種方式創建，分別是：
virsh snapshot 相關命令進行生成快照
qemu-img snapshot 命令進行生成快照
使用virsh進行KVM虛擬機快照相關命令：
iface-begin 創建一個當前網卡的快照，它可以用來稍後提交或者恢復
snapshot-create 創建一個快照
snapshot-create-as 使用一組參數創建一個快照
snapshot-current 取得當前快照的集合
snapshot-delete 刪除一個快照
snapshot-dumpxml 從一個虛擬機的快照導出xml文件
snapshot-edit 編輯一個快照的xml文件
snapshot-info 快照信息
snapshot-list 列出虛擬機的快照列表
snapshot-parent 獲取一個快照的父快照名稱
snapshot-revert 將虛擬機恢復到一個快照
使用virsh管理虛擬機快照：
kvm虛擬機默認使用raw格式的鏡像格式，性能最好，速度最快，它的缺點就是不支持一些新的功能，如支持鏡像,zlib磁盤壓縮,AES加密等。要使用鏡像功能，磁盤格式必須為qcow2。
1、磁盤格式轉換
查看磁盤映像格式：
[root@kvm-node1 ~]# qemu-img info /images/kvm/centos6.img image: /images/kvm/centos6.img file format: raw virtual size: 10G (10737418240 bytes) disk size: 1.5G
關閉虛擬機：
[root@kvm-node1 ~]# virsh list Id Name State ---------------------------------------------------- 1 centos6.5 running [root@kvm-node1 ~]# virsh destroy centos6.5 Domain centos6.5 destroyed [root@kvm-node1 ~]# virsh list Id Name State ----------------------------------------------------
將虛擬機磁盤映像轉換為qcow2格式：
[root@kvm-node1 ~]# qemu-img convert -f raw -O qcow2 /images/kvm/centos6.img /images/kvm/centos6.qcow2 [root@kvm-node1 ~]# qemu-img info /images/kvm/centos6.qcow2 image: /images/kvm/centos6.qcow2 file format: qcow2 virtual size: 10G (10737418240 bytes) disk size: 1.3G cluster_size: 65536 [root@kvm-node1 ~]# ll /images/kvm/centos6* -rwxr-xr-x 1 root root 10737418240 Jul 1 20:13 /images/kvm/centos6.img -rw-r--r-- 1 root root 1394081792 Jul 1 20:17 /images/kvm/centos6.qcow2
使用qemu-img轉換鏡像只是對原有的鏡像做了備份，原有的磁盤映像文件還在。
2、修改虛擬機xml配置文件
修改虛擬機的xml配置文件，主要是把虛擬機的磁盤映像文件修改為我們轉換後的qcow2格式，然後啟動虛擬機，才能執行快照操作。
[root@kvm-node1 ~]# virsh edit centos6.5
Domain centos6.5 XML configuration not changed.
[root@kvm-node1 ~]# awk -F"'" '/<driver name(.*)cache=/{print $4}' /etc/libvirt/qemu/centos6.5.xml #獲取磁盤映像的類型，原來是raw，已經修改為qcow2
qcow2
[root@kvm-node1 ~]# awk -F"'" '/<source file/{print $2}' /etc/libvirt/qemu/centos6.5.xml #獲取磁盤映像文件路徑，原來是centos6.img，這裏已經修改為centos6.qcow2
/images/kvm/centos6.qcow23、啟動虛擬機
[root@kvm-node1 ~]# virsh start centos6.5 Domain centos6.5 started
4、使用virsh命令創建快照
[root@kvm-node1 ~]# virsh snapshot-create centos6.5 Domain snapshot 1530448868 created
5、查看快照
[root@kvm-node1 ~]# virsh snapshot-list centos6.5 Name Creation Time State ------------------------------------------------------------ 1530448868 2018-07-01 20:41:08 +0800 running [root@kvm-node1 ~]# virsh snapshot-info --current centos6.5 Name: 1530448868 Domain: centos6.5 Current: yes State: running Location: internal Parent: - Children: 0 Descendants: 0 Metadata: yes
6、查看當前虛擬機快照的版本
[root@kvm-node1 ~]# virsh snapshot-current centos6.5
<domainsnapshot>
<name>1530448868</name>
<state>running</state>
<creationTime>1530448868</creationTime>
<memory snapshot='internal'/>
<disks>
<disk name='vda' snapshot='internal'/>
<disk name='hdc' snapshot='no'/>
</disks>
<domain type='kvm'>
<name>centos6.5</name>
<uuid>be73fe50-fb80-d468-9e8a-e542f413d735</uuid>
<memory unit='KiB'>1024000</memory>
<currentMemory unit='KiB'>524288</currentMemory>
<vcpu placement='static' current='1'>4</vcpu>
<os>
<type arch='x86_64' machine='rhel6.6.0'>hvm</type>
<boot dev='hd'/>
</os>
<features>
<acpi/>
<apic/>
<pae/>
</features>
<clock offset='utc'/>
<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='/images/kvm/centos6.qcow2'/>
<target dev='vda' bus='virtio'/>
<address type='pci' domain='0x0000' bus='0x00' slot='0x05' function='0x0'/>
</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='bridge'>
<mac address='52:54:00:26:5a:8d'/>
<source bridge='virbr0'/>
<model type='virtio'/>
<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='tablet' bus='usb'/>
<input type='mouse' bus='ps2'/>
<graphics type='vnc' port='5900' 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='0x06' function='0x0'/>
</memballoon>
</devices>
</domain>
</domainsnapshot>7、查看快照配置文件所在目錄
[root@kvm-node1 ~]# ll /var/lib/libvirt/qemu/snapshot/ total 4 drwxr-xr-x 2 root root 4096 Jul 1 20:41 centos6.5 [root@kvm-node1 ~]# ll /var/lib/libvirt/qemu/snapshot/centos6.5/ total 4 -rw------- 1 root root 3492 Jul 1 20:41 1530448868.xml
8、刪除一個快照
[root@kvm-node1 ~]# virsh snapshot-list centos6.5 Name Creation Time State ------------------------------------------------------------ 1530448868 2018-07-01 20:41:08 +0800 running [root@kvm-node1 ~]# virsh snapshot-delete centos6.5 1530448868 Domain snapshot 1530448868 deleted [root@kvm-node1 ~]# virsh snapshot-list centos6.5 Name Creation Time State ------------------------------------------------------------
9、恢復一個快照
1)首先，我們在centos6.5上創建一個文件，例如：
echo "This is a SNAPSHOT test." > /root/testfile
2)使用virsh snapshot-create-as創建一個快照
[root@kvm-node1 ~]# virsh snapshot-create-as --domain centos6.5 --name "centos6.5_snapshot_01" --description "snapshot with testfile saved." Domain snapshot centos6.5_snapshot_01 created
3）查看當前虛擬機的快照列表
[root@kvm-node1 ~]# virsh snapshot-list centos6.5 Name Creation Time State ------------------------------------------------------------ centos6.5_snapshot_01 2018-07-01 21:43:54 +0800 running
4）查看當前虛擬機的快照信息
[root@kvm-node1 ~]# virsh snapshot-info centos6.5 --current Name: centos6.5_snapshot_01 Domain: centos6.5 Current: yes State: running Location: internal Parent: - Children: 0 Descendants: 0 Metadata: yes
5）在虛擬機上刪除testfile
6）使用virsh snapshot-revert恢復虛擬機快照
[root@kvm-node1 ~]# virsh snapshot-revert centos6.5 centos6.5_snapshot_01 --running
snapshot-revert用法：snapshot-revert <domain> [<snapshotname>] [--current] [--running] [--paused] [--force]
選項：
[--domain] <string> ：指定domain名稱，id或者uuid
[--snapshotname] <string> ： 指定快照名稱
--current ：恢復到當前快照
--running ：在恢復快照後自動運行虛擬機
--paused ：在恢復快照後自動暫停虛擬機
--force ：強制執行快照，有風險的恢復選項
[root@kvm-node1 ~]# virsh list Id Name State ---------------------------------------------------- 2 centos6.5 running
7）到虛擬機中查看testfile的內容
使用qemu-img管理虛擬機快照：
qemu-img snapshot選項：
-a：應用一個快照，即使用該快照還原（還原磁盤文件快照時的狀態）-c：創建一個快照
-d：刪除一個快照
-l：列出給定磁盤映像的快照列表
1、為虛擬機創建快照
[root@kvm-node1 ~]# qemu-img snapshot -c centos6.5_snapshot_02 /images/kvm/centos6.qcow2
2、查看虛擬機快照
[root@kvm-node1 ~]# qemu-img snapshot -l /images/kvm/centos6.qcow2 Snapshot list: ID TAG VM SIZE DATE VM CLOCK 1 centos6.5_snapshot_01 166M 2018-07-01 21:43:54 01:08:54.228 2 centos6.5_snapshot_02 0 2018-07-01 22:01:34 00:00:00.000
上面的兩個快照，第一個是使用vrish創建，第二個是使用qemu-img創建
3、恢復快照
[root@kvm-node1 ~]# qemu-img snapshot -a centos6.5_snapshot_02 /images/kvm/centos6.qcow2
4、刪除快照
[root@kvm-node1 ~]# qemu-img snapshot -d centos6.5_snapshot_02 /images/kvm/centos6.qcow2
KVM虛擬機快照