一、使用DomU自有kernel来启动运行DomU
上篇博文中创建的pv格式的vm，内核和引导文件都是放在DomU中，
1、准备磁盘映像文件
losetup
losetup -a: 显示所有已用的loop设备相关信息
losetup -f: 显示第一个空闲的loop设备文件
losetup -d：拆除loop设备
[root@BAIYU_175 xen]# qemu-img create -f raw -o size=5G busybox3.img
Formatting 'busybox3.img', fmt=raw size=5368709120
[root@BAIYU_175 xen]# mount -o loop /p_w_picpaths/xen/busybox.img /mnt
#这个命令会自动调用losetup，把磁盘镜像文件和回环设备建立关联关系
[root@BAIYU_175 xen]# losetup -a
/dev/loop0: [0802]:538231 (/p_w_picpaths/xen/busybox.img)
[root@BAIYU_175 xen]# losetup -f
/dev/loop1
[root@BAIYU_175 xen]# umount /mnt
[root@BAIYU_175 xen]# losetup /dev/loop0 /p_w_picpaths/xen/busybox3.img #挂载后可以进行分区
[root@BAIYU_175 xen]# losetup -a
/dev/loop0: [0802]:524756 (/p_w_picpaths/xen/busybox3.img)
[root@BAIYU_175 xen]# losetup -f
/dev/loop1
[root@BAIYU_175 xen]# fdisk /dev/loop1
Unable to read /dev/loop1
[root@BAIYU_175 xen]# fdisk /dev/loop0
Device contains neither a valid DOS partition table, nor Sun, SGI or OSF disklabel
Building a new DOS disklabel with disk identifier 0x4778379d.
Changes will remain in memory only, until you decide to write them.
After that, of course, the previous content won't be recoverable.
Warning: invalid flag 0x0000 of partition table 4 will be corrected by w(rite)
WARNING: DOS-compatible mode is deprecated. It's strongly recommended to
switch off the mode (command 'c') and change display units to
sectors (command 'u').
Command (m for help): p
Disk /dev/loop0: 5368 MB, 5368709120 bytes
255 heads, 63 sectors/track, 652 cylinders
Units = cylinders of 16065 * 512 = 8225280 bytes
Sector size (logical/physical): 512 bytes / 512 bytes
I/O size (minimum/optimal): 512 bytes / 512 bytes
Disk identifier: 0x4778379d
Device Boot Start End Blocks Id System
Command (m for help): m
Command action
a toggle a bootable flag
b edit bsd disklabel
c toggle the dos compatibility flag
d delete a partition
l list known partition types
m print this menu
n add a new partition
o create a new empty DOS partition table
p print the partition table
q quit without saving changes
s create a new empty Sun disklabel
t change a partition's system id
u change display/entry units
v verify the partition table
w write table to disk and exit
x extra functionality (experts only)
Command (m for help): n
Command action
e extended
p primary partition (1-4)
p
Partition number (1-4):
Value out of range.
Partition number (1-4): 2
First cylinder (67-652, default 67):
Using default value 67
Last cylinder, +cylinders or +size{K,M,G} (67-652, default 652): +2G
Command (m for help): p
Disk /dev/loop0: 5368 MB, 5368709120 bytes
255 heads, 63 sectors/track, 652 cylinders
Units = cylinders of 16065 * 512 = 8225280 bytes
Sector size (logical/physical): 512 bytes / 512 bytes
I/O size (minimum/optimal): 512 bytes / 512 bytes
Disk identifier: 0xbb6d135d
Device Boot Start End Blocks Id System
/dev/loop0p1 1 66 530113+ 83 Linux
/dev/loop0p2 67 328 2104515 83 Linux
Command (m for help): w
[root@BAIYU_175 xen]# kpartx /dev/loop0
loop0p1 : 0 1060227 /dev/loop0 63
loop0p2 : 0 4209030 /dev/loop0 1060290
[root@BAIYU_175 xen]# kpartx -av /dev/loop0
add map loop0p1 (253:0): 0 1060227 linear /dev/loop0 63
add map loop0p2 (253:1): 0 4209030 linear /dev/loop0 1060290
[root@BAIYU_175 xen]# ls /dev/mapper/
control loop0p1 loop0p2
[root@BAIYU_175 xen]# mke2fs -t ext4 /dev/mapper/loop0p1
[root@BAIYU_175 xen]# mke2fs -t ext4 /dev/mapper/loop0p2
[root@BAIYU_175 xen]# mkdir /mnt/{boot,sysroot}
[root@BAIYU_175 xen]# mount /dev/mapper/loop0p1 /mnt/boot/
[root@BAIYU_175 xen]# mount /dev/mapper/loop0p2 /mnt/sysroot/
[root@BAIYU_175 xen]# cp /boot/vmlinuz-2.6.32-573.el6.x86_64 /mnt/boot/vmlinuz
[root@BAIYU_175 xen]# cp /boot/initramfs-2.6.32-573.el6.x86_64.img /mnt/boot/initramfs.img
[root@BAIYU_175 xen]# grub-install --root-directory=/mnt /dev/loop0
#创建grub文件，
Probing devices to guess BIOS drives. This may take a long time.
/dev/loop0 does not have any corresponding BIOS drive.
[root@BAIYU_175 xen]# ls /mnt/boot/grub/
device.map ffs_stage1_5 minix_stage1_5 stage2 xfs_stage1_5
e2fs_stage1_5 iso9660_stage1_5 reiserfs_stage1_5 ufs2_stage1_5
fat_stage1_5 jfs_stage1_5 stage1 vstafs_stage1_5
[root@BAIYU_175 xen]# vi /mnt/boot/grub/grub.conf
[root@BAIYU_175 xen]# cat /mnt/boot/grub/grub.conf
default=0
timeout=5
title BusyBox(kernel-2.6.32)
root (hd0,0)
kernel /vmlinuz root=/dev/xvda1 ro selinux=0 init=/bin/sh
initrd /initramfs.img
[root@BAIYU_175 ~]# cp -a busybox-1.22.1/_install/* /mnt/sysroot
[root@BAIYU_175 ~]# cd /mnt/sysroot/
[root@BAIYU_175 sysroot]# ls
bin linuxrc lost+found sbin usr
[root@BAIYU_175 sysroot]# mkdir lib/modules dev proc sysc etc var tmp -pv
mkdir: 已创建目录 "lib"
mkdir: 已创建目录 "lib/modules"
mkdir: 已创建目录 "dev"
mkdir: 已创建目录 "proc"
mkdir: 已创建目录 "sysc"
mkdir: 已创建目录 "etc"
mkdir: 已创建目录 "var"
mkdir: 已创建目录 "tmp"
[root@BAIYU_175 sysroot]# cp /lib/modules/2.6.32-573.el6.x86_64/kernel/drivers/net/xen-netfront.ko lib/modules
[root@BAIYU_175 ~]# losetup -a
/dev/loop0: [0802]:524756 (/p_w_picpaths/xen/busybox3.img)
[root@BAIYU_175 ~]# kpartx -d /dev/loop0
[root@BAIYU_175 ~]# losetup -a
[root@BAIYU_175 ~]# cd /etc/xen/
[root@BAIYU_175 xen]# ls
auto busybox2 busybox.orig scripts vm2.orig xlexample.hvm
busybox busybox2.orig cpupool vm2 xl.conf xlexample.pvlinux
[root@BAIYU_175 xen]# cp busybox busybox3
[root@BAIYU_175 xen]# vi busybox3
[root@BAIYU_175 xen]# grep -v '^#\|^$' busybox3
name = "anyfish-003"
memory = 256
vcpus = 2
vif = [ 'bridge=xenbr0' ]
disk = [ '/p_w_picpaths/xen/busybox3.img,raw,xvda,rw' ]
bootloader='/usr/bin/pygrub'
[root@BAIYU_175 xen]# xl create busybox3 -c
二、创建虚拟机并完成Centos6.5系统安装
1、创建磁盘映像文件；
2、获取安装指定版本的系统所需要kernel及initrd文件；
3、创建DomU配置文件，示例如下：
name = "centos-001" kernel = "/p_w_picpaths/kernel/vmlinuz" ramdisk = "/p_w_picpaths/kernel/initrd.img" extra = "ks=http://172.16.0.1/centos6.x86_64.cfg" memory = 512 vcpus = 2 vif = [ 'bridge=xenbr0' ] disk = [ '/p_w_picpaths/xen/centos6.6.img,qcow2,xvda,rw' ] on_reboot = "shutdown"
4、安装完成后，创建虚拟机的配置文件需要做出修改；
name = "centos-001" bootloader = "pygrub" memory = 512 vcpus = 2 vif = [ 'bridge=xenbr0' ] disk = [ '/p_w_picpaths/xen/centos6.6.img,qcow2,xvda,rw' ]
启动图形窗口：
在创建虚拟机的配置文件中定义vfb
(1) vfb = [ 'sdl=1' ]
(2) vnc
(a) yum install tigervnc
(b) vfb = [ 'vnc=1' ]
vnc监听的端口为5900, 相应的DISPLAYNUM为0
使用Dom0中物理磁盘分区为DomU提供存储空间：
三、使用libvirt实现xen虚拟机管理
yum install libvirt libvirt-deamon-xen virt-manager python-virtinst libvirt-client
service libvirtd start
virt-manager, virsh, virt-install
四、总结一下前面学的内容
1、xen:是Type-I的虚拟化技术解决方案
2、三个组件
Xen Hypervisor：分配cpu、内存、interrupt（中断）
Dom0：特权域，驱动I/O，并为DomU提供模拟的IO设备，
Xen管理工具栈
xm:
xl：
libvirt/virsh：
DomU：非特权域
Guest OS
3、工作模式
PV
FV（HVM）
PV on HVM：I/O半虚拟化但cpu完全虚拟化
4、安装Xen Hyperversionz的过程
安装CentOS-->安装Xen及能运行于Dom0中的内核-->修改/etc/grub.conf以xen.gz为内核，而原来的内核及ramdisk做为xen的模块使用，
5、创建虚拟机的过程
两种方式：
由Dom0提供内核：
kernel= 路径
ramdisk= 路径
根文件系统，
由DomU提供内核：
在配置文件中添加bootloader=“pygrub”
五、xen虚拟机实时迁移
前言：
xen虚拟机提供了一种类似于heartbeat高可用方案，在保证也不中断的业务情况下实现虚拟机迁移技术。在保证虚拟机上的服务正常的情况下将运行中的Domain迁移到其他机器上，实现xen虚拟机的高可用。
1、实验准备
(1)各个测试机之间时间要同步
(2)node3提供iscsi网络共享存储
(4)node4与node5做为xen虚拟机
(5)本人使用的都是CentOS6.5操作系统
(6)关闭所有节点的iptables和SELinux
对busybox小系统进行实施迁移
修改node4节点与node5节点的xen配置文件，开启以下选项
[root@node4 ~]# vim /etc/xen/xend-config.sxp (xend-relocation-server yes) (xend-relocation-port 8002) (xend-address '172.16.2.16') (xend-relocation-hosts-allow '') [root@node5 ~]# vim /etc/xen/xend-config.sxp (xend-relocation-server yes) (xend-relocation-port 8002) (xend-address '172.16.2.15') (xend-relocation-hosts-allow '') [root@node4 ~]# service xend restart;ssh node5 'service xend restart' Stopping xend daemon: [ OK ] Starting xend daemon: [ OK ] Stopping xend daemon: [ OK ] Starting xend daemon: [ OK ]
将运行在node5节点的busybox小系统迁移到node4节点
[root@node5 ~]# xm migrate -l busybox 172.16.2.15 \\将busybox系统迁移到node4节点 [root@node4 ~]# xm list \\在node4节点查看，busybox已经成功移植到node4节点 Name ID Mem VCPUs State Time(s) Domain-0 0 1024 1 r----- 427.8 busybox 3 512 2 -b---- 0.1 [root@node5 ~]# xm list \\node5节点已经没由DomU在运行 Name ID Mem VCPUs State Time(s) Domain-0 0 1024 1 r----- 64.7
实际生产环境中可对Xen平台做高可用，当物理机故障可移动检测并进行实时迁移，保证业务不受影响。