Xen实战之基于CentOS6.5安装Xen4.2
声明
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Xen4CentOS项目介绍
Xen4CentOS 项目致力提供建基于 Xen-4.2 的 xen 堆栈、一个以 3.4 LTS 主流树为本的 Linux 内核、并在发行版本内以 libvirt 和 qemu 的相关工具来支持 Xen。它由 Xen 计划、Citrix Xen 开源小组、CentOS 开发者、GoDaddy 云端运作小组、Rackspace 网站讬管及 CentOS QA 小组共同参与，旨在为CentOS-5／Xen 的用户把他们的基本结构移植及升级至 CentOS-6，同一时间更引入较新的 Xen-4 工具链。
目前该项目有一些已知问题需要注意：
- SELinux 支持已停用，你或许会需要为某些操作在 dom0 上停用 SELinux，当中主要有 qemu-xen 及 blktap 的存储后台;
- 暂时，只在 CentOS-6／x86_64 上支持 Xen4CentOS;
- 假若有需要重新配置 dom0 的控制台，你必须以手动方式设置序列控制台
- 虽然 xenlight 及 xm 皆是获支持的 xen 命令行工具，而且都通过详尽测试，唯有 xm（需执行着 xend）能套用 libvirt 的所有功能。希望在将来的发行版本中为 Libvirt 提供原生的 xl 支持。
CentOS6.5的安装
首先明确对机器的要求：拥有至少1.5GB内存，10GB以上的磁盘空间供根目录/使用。
其次运行Xen的主机应该是一台 CentOS-6／x86_64 的最少安装；CentOS 的 Xen4 堆栈只在 CentOS-6.4 及往后版本上进行测试及检验。
最后在进行下一步之先，请确保 yum 只启用了 CentOS 的软件库，而且你已采用了最新的更新。
CentOS6.5的最小安装ISO文件CentOS-6.5-x86_64-minimal.iso可以从搜狐镜像服务器上获取: http://mirrors.sohu.com/centos/6/isos/x86_64
CentOS6.5系统安装以后，关闭SELinux的功能(缺省为enforcing状态)：
[root@centos ~]# getenforce Enforcing [root@centos ~]# vi /etc/sysconfig/selinux # This file controls the state of SELinux on the system. # SELINUX= can take one of these three values: # enforcing - SELinux security policy is enforced. # permissive - SELinux prints warnings instead of enforcing. # disabled - No SELinux policy is loaded. SELINUX=disabled # SELINUXTYPE= can take one of these two values: # targeted - Targeted processes are protected, # mls - Multi Level Security protection. SELINUXTYPE=targeted [root@centos ~]# reboot更新系统，安装perl工具包(Xen工具需要使用Perl工具包，CentOS最小安装不支持Perl):
[root@centos ~]# yum install perl [root@centos ~]# yum update [root@centos ~]# reboot
安装Xen4CentOS
安装Xen对象的软件包并修改grub配置文件：
[root@centos ~]# yum install centos-release-xen [root@centos ~]# yum install xen [root@centos ~]# /usr/bin/grub-bootxen.sh
Xen是在linux内核之上运行，所以我们必须告诉grub先引导Xen，然后顺序引导dom0的linux内核。要达至这个目的，centos-release-xen 的组件内已包含一个脚本grub-bootxen.sh，用来自动修改/boot/grub/grub.conf配置文件：
[root@centos ~]# more /usr/bin/grub-bootxen.sh #!/bin/bash # # (c) Simon Rowe, 2013 # (c) Karanbir Singh, 2013 default=$(grubby --default-kernel) kver=$(expr $default : '.*vmlinuz-\(.*\)') [ -n "$kver" ] || exit 0 initrd=$(grubby --info $default | sed -ne 's/^initrd=//p') new-kernel-pkg --install --package kernel --multiboot=/boot/xen.gz "--mbargs=dom0_mem=1024M,max:1024M loglvl=all guest_loglvl=all" - -initrdfile=$initrd $kver exit $?修改后的grub.conf文件：
[root@centos ~]# more /boot/grub/grub.conf
# grub.conf generated by anaconda
#
# Note that you do not have to rerun grub after making changes to this file
# NOTICE: You have a /boot partition. This means that
# all kernel and initrd paths are relative to /boot/, eg.
# root (hd0,0)
# kernel /vmlinuz-version ro root=/dev/mapper/vg_centos-LogVol01
# initrd /initrd-[generic-]version.img
#boot=/dev/sda
default=0
timeout=5
splashimage=(hd0,0)/grub/splash.xpm.gz
hiddenmenu
title CentOS (3.10.32-11.el6.centos.alt.x86_64)
root (hd0,0)
kernel /xen.gz dom0_mem=1024M,max:1024M loglvl=all guest_loglvl=all
module /vmlinuz-3.10.32-11.el6.centos.alt.x86_64 ro root=/dev/mapper/vg_centos-LogVol01 rd_NO_LUKS rd_LVM_LV=vg_centos/LogVo
l00 rd_LVM_LV=vg_centos/LogVol01 rd_NO_MD SYSFONT=latarcyrheb-sun16 crashkernel=auto KEYBOARDTYPE=pc KEYTABLE=us rd_NO_DM LANG=en_U
S.UTF-8 rhgb quiet
module /initramfs-3.10.32-11.el6.centos.alt.x86_64.img
.....系统重启以后可以检查运行版本是否与grub.conf中配置一致及Xen是否在运行中：
[root@centos ~]# uname -r 3.10.32-11.el6.centos.alt.x86_64 [root@centos ~]# xm list Name ID Mem VCPUs State Time(s) Domain-0 0 1024 4 r----- 20.6
网络配置
系统安装以后，需要对网络进行配置，这里介绍的是桥接方式进行网络配置。配置之前相关的网络配置：
[root@centos ~]# more /etc/sysconfig/network-scripts/ifcfg-eth0
DEVICE=eth0
HWADDR=00:0C:29:FA:F3:90
TYPE=Ethernet
UUID=c49a6cdc-44fc-4908-ad81-4df0d3984c65
ONBOOT=yes
NM_CONTROLLED=yes
BOOTPROTO=none
IPADDR=10.220.33.79
PREFIX=24
GATEWAY=10.220.33.1
DNS1=10.220.32.12
DEFROUTE=yes
NAME=eth0
[root@centos network-scripts]# ifconfig
eth0 Link encap:Ethernet HWaddr 00:0C:29:FA:F3:90
inet addr:10.220.33.79 Bcast:10.220.33.255 Mask:255.255.255.0
inet6 addr: fe80::20c:29ff:fefa:f390/64 Scope:Link
UP BROADCAST RUNNING MULTICAST MTU:1500 Metric:1
RX packets:1469 errors:0 dropped:0 overruns:0 frame:0
TX packets:486 errors:0 dropped:0 overruns:0 carrier:0
collisions:0 txqueuelen:1000
RX bytes:257573 (251.5 KiB) TX bytes:59515 (58.1 KiB)
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: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)
[root@centos ~]# brctl show
bridge name bridge id STP enabled interfaces
创建xenbr0网桥，eth0以太网物理网卡桥接到此网桥上，并创建xenbr0虚拟物理网卡，并配置相关的接口地址，桥接方式的逻辑示意图如下图所示
# To bridge network traffic, like this: # # dom0: ----------------- bridge -> real eth0 -> the network # | # domU: fake eth0 -> vifN.0 -+创建及修改过程log：
[root@centos ~]# brctl addbr xenbr0 [root@centos ~]# brctl show bridge name bridge id STP enabled interfaces xenbr0 8000.000000000000 no [root@centos ~]# cd /etc/sysconfig/network-scripts [root@centos network-scripts]# cp ifcfg-eth0 ifcfg-xenbr0 [root@centos network-scripts]# vi ifcfg-xenbr0 DEVICE=xenbr0 TYPE=Bridge ONBOOT=yes NM_CONTROLLED=yes BOOTPROTO=none IPADDR=10.220.33.79 PREFIX=24 GATEWAY=10.220.33.1 DNS1=10.220.32.12 DEFROUTE=yes NAME=xenbr0 [root@centos network-scripts]# vi ifcfg-eth DEVICE=eth0 HWADDR=00:0C:29:FA:F3:90 TYPE=Ethernet UUID=c49a6cdc-44fc-4908-ad81-4df0d3984c65 ONBOOT=yes NM_CONTROLLED=yes BOOTPROTO=none DEFROUTE=yes NAME=eth0 BRIDGE=xenbr0 [root@centos network-scripts]# service network restart查看实际生效的配置：
[root@centos ~]# brctl show
bridge name bridge id STP enabled interfaces
xenbr0 8000.000c29faf390 no eth0
[root@centos ~]# ifconfig
eth0 Link encap:Ethernet HWaddr 00:0C:29:FA:F3:90
inet6 addr: fe80::20c:29ff:fefa:f390/64 Scope:Link
UP BROADCAST RUNNING MULTICAST MTU:1500 Metric:1
RX packets:88988 errors:0 dropped:0 overruns:0 frame:0
TX packets:605 errors:0 dropped:0 overruns:0 carrier:0
collisions:0 txqueuelen:1000
RX bytes:8708966 (8.3 MiB) TX bytes:94984 (92.7 KiB)
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:10 errors:0 dropped:0 overruns:0 frame:0
TX packets:10 errors:0 dropped:0 overruns:0 carrier:0
collisions:0 txqueuelen:0
RX bytes:1056 (1.0 KiB) TX bytes:1056 (1.0 KiB)
xenbr0 Link encap:Ethernet HWaddr 00:0C:29:FA:F3:90
inet addr:10.220.33.79 Bcast:10.220.33.255 Mask:255.255.255.0
inet6 addr: fe80::20c:29ff:fefa:f390/64 Scope:Link
UP BROADCAST RUNNING MULTICAST MTU:1500 Metric:1
RX packets:18463 errors:0 dropped:0 overruns:0 frame:0
TX packets:330 errors:0 dropped:0 overruns:0 carrier:0
collisions:0 txqueuelen:0
RX bytes:1544430 (1.4 MiB) TX bytes:62200 (60.7 KiB)
安装GNOME桌面
安装Desktop，X Window System包，并修改启动级别。
[root@centos etc]# yum groupinstall Desktop [root@centos etc]# yum groupinstall "X Window System" [root@centos etc]# vi inittab # inittab is only used by upstart for the default runlevel. # # ADDING OTHER CONFIGURATION HERE WILL HAVE NO EFFECT ON YOUR SYSTEM. # # System initialization is started by /etc/init/rcS.conf # # Individual runlevels are started by /etc/init/rc.conf # # Ctrl-Alt-Delete is handled by /etc/init/control-alt-delete.conf # # Terminal gettys are handled by /etc/init/tty.conf and /etc/init/serial.conf, # with configuration in /etc/sysconfig/init. # # For information on how to write upstart event handlers, or how # upstart works, see init(5), init(8), and initctl(8). # # Default runlevel. The runlevels used are: # 0 - halt (Do NOT set initdefault to this) # 1 - Single user mode # 2 - Multiuser, without NFS (The same as 3, if you do not have networking) # 3 - Full multiuser mode # 4 - unused # 5 - X11 # 6 - reboot (Do NOT set initdefault to this) # id:5:initdefault:
参考资料
1. http://wiki.centos.org/zh/HowTos/Xen