kvm 学习（二）镜像

Linux下 如何通过命令行使用现有的镜像创建、启动kvm虚拟机

这里假定已经创建好了相应的镜像：

eg：我这里制作的镜像名称为zu1-centos7.img

# ls
 zu1-centos7.img  

1、拷贝这个镜像到某一个目录

cp zu1-centos7.img /data2/

2、编写镜像的配置文件，当然一般情况是从其他镜像的配置文件拷贝一份，重新命名在修改

# cd /etc/libvirt/qemu   进入到镜像配置文件目录
# cp test2.xml test3.xml   test2.xml是其他镜像存在的配置文件，test3.xml是当前准备启动的镜像的配置文件

test2.xml配置文件大体如下：

<!--
WARNING: THIS IS AN AUTO-GENERATED FILE. CHANGES TO IT ARE LIKELY TO BE
OVERWRITTEN AND LOST. Changes to this xml configuration should be made using:
  virsh edit test2
or other application using the libvirt API.
-->

<domain type='kvm'>
  <name>test2</name>                     ---虚拟机名字，记得修改，随便起什么名字都行，只要不跟其他虚拟机名字一样就行
  <uuid>92047c95-c5b8-4e4d-916c-fb2218ca055f</uuid>    --uuid  记得修改，一般来说，把最好的四位数字重新修改一下，例如我把最后四位改成0001，具体效果看下个test3.xml文件
  <memory unit='KiB'>10485760</memory>      ---当前虚拟机使用内存，看自己情况是否需要修改
  <currentMemory unit='KiB'>10485760</currentMemory>   ---当前虚拟机可以使用的最大内存，使用内存不得超过这个内存，当使用内存不足的时候，可以在虚拟机里面动态调整内存。
  <vcpu placement='static'>1</vcpu>
  <os>
    <type arch='x86_64' machine='rhel6.6.0'>hvm</type>   ---架构，一般不用修改
    <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'/>   ---driver类型，需要跟镜像的文件格式一致。以前老版本默认是raw类型，现在默认是qcow2类型。查看镜像的文件格式在该配置文件的下面：
      <source file='/data1/iso/zu1-centos7.img'/>        --- 镜像文件路径
      <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='qcow2'/>
      <target dev='hdc' bus='ide'/>
      <readonly/>
      <address type='drive' controller='0' bus='1' target='0' unit='0'/>
    </disk>
    <controller type='ide' index='0'>
      <address type='pci' domain='0x0000' bus='0x00' slot='0x01' function='0x1'/>
    </controller>
    <controller type='usb' index='0' model='piix3-uhci'>
      <address type='pci' domain='0x0000' bus='0x00' slot='0x01' function='0x2'/>
    </controller>
    <controller type='pci' index='0' model='pci-root'/>
    <interface type='bridge'>
      <mac address='52:54:00:5a:07:de'/>
      <source bridge='br0'/>
      <model type='virtio'/>
      <address type='pci' domain='0x0000' bus='0x00' slot='0x03' function='0x0'/>   ---这里的slot号记得修改  把最后两位改成其他的就行，但不要跟其他的虚拟机配置的值一样，同时，这个值不超过 0x0f
    </interface>
    <serial type='pty'>
      <target type='isa-serial' port='0'>
        <model name='isa-serial'/>
      </target>
    </serial>
    <console type='pty'>
      <target type='serial' port='0'/>
    </console>
    <input type='tablet' bus='usb'>
      <address type='usb' bus='0' port='1'/>
    </input>
    <input type='mouse' bus='ps2'/>
    <input type='keyboard' bus='ps2'/>
    <memballoon model='virtio'>
      <address type='pci' domain='0x0000' bus='0x00' slot='0x06' function='0x0'/>
    </memballoon>
  </devices>
</domain>

3、查看镜像的driver类型

# qemu-img info /data1/zu1-centos7.img
image: /data1/virtcentos/pool/zu1-centos7.img
file format: qcow2     ----这里就是镜像的文件格式
virtual size: 20G (21474836480 bytes)
disk size: 18G
cluster_size: 65536
Format specific information:
    compat: 1.1
    lazy refcounts: true

4、修改test3.xml文件，如下：

<!--
WARNING: THIS IS AN AUTO-GENERATED FILE. CHANGES TO IT ARE LIKELY TO BE
OVERWRITTEN AND LOST. Changes to this xml configuration should be made using:
  virsh edit test2
or other application using the libvirt API.
-->

<domain type='kvm'>
  <name>yjt</name>    ---这里改成了yjt
  <uuid>92047c95-c5b8-4e4d-916c-fb2218ca0001</uuid>
  <memory unit='KiB'>10485760</memory>
  <currentMemory unit='KiB'>10485760</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='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='/data2/zu1-centos7.img'/>    ---这里修改了镜像的路径
      <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='qcow2'/>
      <target dev='hdc' bus='ide'/>
      <readonly/>
      <address type='drive' controller='0' bus='1' target='0' unit='0'/>
    </disk>
    <controller type='ide' index='0'>
      <address type='pci' domain='0x0000' bus='0x00' slot='0x01' function='0x1'/>
    </controller>
    <controller type='usb' index='0' model='piix3-uhci'>
      <address type='pci' domain='0x0000' bus='0x00' slot='0x01' function='0x2'/>
    </controller>
    <controller type='pci' index='0' model='pci-root'/>
    <interface type='bridge'>
      <mac address='52:54:00:5a:07:de'/>
      <source bridge='br0'/>
      <model type='virtio'/>
      <address type='pci' domain='0x0000' bus='0x00' slot='0x10' function='0x0'/>   这里改成了0x10，注意,该值不得超过0x0f
    </interface>
    <serial type='pty'>
      <target type='isa-serial' port='0'>
        <model name='isa-serial'/>
      </target>
    </serial>
    <console type='pty'>
      <target type='serial' port='0'/>
    </console>
    <input type='tablet' bus='usb'>
      <address type='usb' bus='0' port='1'/>
    </input>
    <input type='mouse' bus='ps2'/>
    <input type='keyboard' bus='ps2'/>
    <memballoon model='virtio'>
      <address type='pci' domain='0x0000' bus='0x00' slot='0x06' function='0x0'/>
    </memballoon>
  </devices>
</domain>

5、定义虚拟机

# virsh define test3.xml  ---定义虚拟机跟上对应的文件即可

6、启动虚拟机

virsh start yjt   ---yjt这个名字在配置文件定义的，也就是虚拟机的名字。

到这里就ok了。

如果虚拟机不要用了，可以使用如下方法销毁

7、停止虚拟机

# virsh shutdown yjt   ---正常停止
# virsh destroy yjt    ---强制停止

8、取消虚拟机的定义，也就是删除

# virsh undefine yjt   ---默认会删除/etc/libvirt/qemu下的test3.xml文件

kvm安装：

https://blog.51cto.com/zero01/2083896