背景
当需要批量部署虚拟机时，通常有几种做法，使用模板重新安装。
或者使用已有的虚拟机克隆。
使用模板安装可以参考kickstart脚本的编写方法。
《install kvm hosts use kickstart in CentOS 6 in text mode》
本文介绍一下在已经安装好的虚拟机上，克隆虚拟机的方法。
从0开始安装一个虚拟机
在服务器安装必要的包, 不再需要图形相关的包.
# yum install -y qemu-img qemu-kvm virt-manager libvirt libvirt-python python-virtinst libvirt-client libvirt libvirt-client virt-what
创建一个虚拟磁盘目录
# mkdir /data03/kvmdisk
创建虚拟磁盘, 用于虚拟机的系统盘
# qemu-img create -f qcow2 -o encryption=off,cluster_size=2M,preallocation=full /data03/kvmdisk/disk01.img 32G
or
# qemu-img create -f raw /data03/kvmdisk/disk01.img 32G
下载安装镜像
# mkdir /data03/iso
# cd iso
# wget http://mirrors.aliyun.com/centos/6.6/isos/x86_64/CentOS-6.6-x86_64-bin-DVD1.iso
配置
vi /etc/libvirt/libvirtd.conf
listen_tls = 0
启动libvirtd
# service libvirtd start
# /etc/init.d/messagebus start
# /etc/init.d/avahi-daemon start
# /etc/init.d/libvirtd start
# chkconfig libvirtd on
# chkconfig libvirt-guests off
# chkconfig avahi-daemon on
# chkconfig messagebus on
查看当前启动的网桥
# brctl show
bridge name bridge id STP enabled interfaces
virbr0 8000.5254001263b0 yes virbr0-nic
# ifconfig
em1 Link encap:Ethernet HWaddr 00:22:19:60:77:8F
inet addr:172.16.3.150 Bcast:172.16.3.255 Mask:255.255.255.0
inet6 addr: fe80::222:19ff:fe60:778f/64 Scope:Link
UP BROADCAST RUNNING MULTICAST MTU:1500 Metric:1
RX packets:5469716 errors:0 dropped:0 overruns:0 frame:0
TX packets:2830916 errors:0 dropped:0 overruns:0 carrier:0
collisions:0 txqueuelen:1000
RX bytes:5147311077 (4.7 GiB) TX bytes:198552462 (189.3 MiB)
lo Link encap:Local Loopback
inet addr:127.0.0.1 Mask:255.0.0.0
inet6 addr: ::1/128 Scope:Host
UP LOOPBACK RUNNING MTU:65536 Metric:1
RX packets:79073 errors:0 dropped:0 overruns:0 frame:0
TX packets:79073 errors:0 dropped:0 overruns:0 carrier:0
collisions:0 txqueuelen:0
RX bytes:24506711 (23.3 MiB) TX bytes:24506711 (23.3 MiB)
virbr0 Link encap:Ethernet HWaddr 52:54:00:12:63:B0
inet addr:192.168.122.1 Bcast:192.168.122.255 Mask:255.255.255.0
UP BROADCAST RUNNING MULTICAST MTU:1500 Metric:1
RX packets:0 errors:0 dropped:0 overruns:0 frame:0
TX packets:0 errors:0 dropped:0 overruns:0 carrier:0
collisions:0 txqueuelen:0
RX bytes:0 (0.0 b) TX bytes:0 (0.0 b)
或者你也可以手工添加网桥
brctl addbr br0
ip link set br0 up
ip addr add 192.168.122.1/24 dev br0
查看虚拟机用到的virbr0网桥地址配置
# grep -r 192.168.122 /etc/libvirt
/etc/libvirt/qemu/networks/default.xml: <ip address="192.168.122.1" netmask="255.255.255.0">
/etc/libvirt/qemu/networks/default.xml: <range start="192.168.122.2" end="192.168.122.254" />
/etc/libvirt/qemu/networks/autostart/default.xml: <ip address="192.168.122.1" netmask="255.255.255.0">
/etc/libvirt/qemu/networks/autostart/default.xml: <range start="192.168.122.2" end="192.168.122.254" />
text 交互式安装虚拟机操作系统
在没有图形环境时, 可以使用text模式安装操作系统.
virt-install --name=centos6_6_x64 --disk path=/data03/kvmdisk/disk01.img,device=disk,bus=virtio,perms=rw,cache=writethrough --graphics none --vcpus=4 --ram=4096 --location=/data03/iso/CentOS-6.6-x86_64-bin-DVD1.iso --network bridge=virbr0 --os-type=linux --os-variant=rhel6 --extra-args="console=tty0 console=ttyS0,115200n8"
安装完后，连接到虚拟机的console的方法
# virsh
> console $domainID
> 退出console 按下 ctrl+]
例如 :
[root@db-172-16-3-150 ~]# virsh
Welcome to virsh, the virtualization interactive terminal.
Type: ‘help‘ for help with commands
‘quit‘ to quit
virsh # list
Id Name State
----------------------------------------------------
2 centos6_6_x64 running
virsh # console 2 # 使用Id或者Name都可以连接
Connected to domain centos6_6_x64
Escape character is ^]
CentOS release 6.6 (Final)
Kernel 2.6.32-504.el6.x86_64 on an x86_64
digoal.sky-mobi.com login: root
Password:
Last login: Thu Apr 2 00:12:27 on ttyS0
[root@digoal ~]#
[root@digoal ~]#
[root@digoal ~]# exit
logout
CentOS release 6.6 (Final)
Kernel 2.6.32-504.el6.x86_64 on an x86_64
digoal.sky-mobi.com login: # 这里按下ctrl+]返回本地控制台
virsh #
virsh #
设置开机自动启动虚拟机
# vi /etc/rc.local
/usr/bin/virsh start centos6_6_x64
优化虚拟机配置
1. 主要是删掉一些不必要的控制器(如USB), 然后添加CPU模块, 使用本地CPU的flag.
#virsh
Welcome to virsh, the virtualization interactive terminal.
Type: ‘help‘ for help with commands
‘quit‘ to quit
virsh #
virsh # list
Id Name State
----------------------------------
6 kvm101 running
8 kvm103 running
9 kvm104 running
10 kvm105 running
11 kvm106 running
12 kvm102 running
优化例子
virsh # edit kvm101
<domain type=‘kvm‘>
<name>kvm101</name>
<uuid>366072c0-2ee0-027a-e887-e60d50bad5a7</uuid>
<memory>83886080</memory>
<currentMemory>83886080</currentMemory>
<vcpu>10</vcpu>
<cpu mode=‘host-passthrough‘> # 注意这里可能要指定CPU，而不是host-passthrough，否则可能保存会失败，或者自动抹除。 /usr/libexec/qemu-kvm -cpu ? 可以得到支持的CPU
<model fallback=‘allow‘/>
</cpu>
--------- 例如 /usr/share/libvirt/cpu_map.xml
<cpu match=‘exact‘>
<model fallback=‘forbid‘>Nehalem</model>
<vendor>Intel</vendor>
<feature policy=‘require‘ name=‘fma‘/> # 这里可以指定CPU flag
<feature policy=‘require‘ name=‘pse‘/> # 这里可以指定CPU flag
</cpu>
---------
<os>
<type arch=‘x86_64‘ machine=‘rhel6.2.0‘>hvm</type>
<boot dev=‘hd‘/>
</os>
<clock offset=‘utc‘/>
<on_poweroff>destroy</on_poweroff>
<on_reboot>restart</on_reboot>
<