CentOS 7 安装与配置 KVM
一、前言
KVM（Kernelbased Virtual Machine）是一种开源的系统虚拟化模块，自Linux内核2.6.20之后集成在Linux的所有主要发行版本中，它使用Linux自身的调度器进行管理，所以相对于Xen，其核心源码很少，KVM目前已成为学术界的主流VMM之一，KVM的虚拟化需要硬件支持（如Intel VT技术或者AMD V技术），是基于硬件的完全虚拟化，可以运行多个本身运行未改动的镜像的虚拟机，例如Windows、Mac OS X等，本文将详细介绍如何在CentOS 7上安装和配置KVM。
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二、准备工作
1、操作系统：确保你的系统为CentOS 7或更高版本。
2、硬件要求：至少4GB内存，处理器支持虚拟化技术（Intel VTx或AMDV）。
3、网络连接：确保服务器具备稳定的网络连接以下载所需的软件包。
三、检查CPU是否支持虚拟化
在开始之前，先确认你的CPU是否支持虚拟化技术，执行以下命令：
- egrep i '(vmx|svm)' /proc/cpuinfo
如果输出包含vmx或svm，则表示你的CPU支持虚拟化。
四、安装KVM及相关组件
1、更新系统：
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确保系统的软件包是最新的：
- sudo yum update y
2、安装KVM相关软件包：
执行以下命令以安装KVM、libvirt以及其他必要的软件包：
- sudo yum install @kvm y
该命令会安装以下主要组件：
qemukvm：KVM的主要模块。
libvirt：提供对KVM进行管理的API。
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virtinstall：用于命令行创建和管理虚拟机的工具。
virtmanager：图形化的虚拟机管理器。
3、启动并设置libvirtd服务：
安装完成后，启动libvirtd服务并设置为开机自启：
- sudo systemctl enable libvirtd
- sudo systemctl start libvirtd
五、验证KVM安装
1、检查KVM模块是否加载：
执行以下命令查看KVM模块是否成功加载：
- lsmod | grep kvm
输出应类似于：
- kvm_intel 183621 0
- kvm 586948 1 kvm_intel
- irqbypass 13503 1 kvm
2、验证libvirt服务：
执行以下命令检查libvirt服务状态：
- sudo systemctl status libvirtd
你应该看到libvirtd服务正在运行。
六、配置桥接网络
默认情况下，KVM使用NAT网络，这意味着虚拟机可以通过主机访问外部网络，但外部网络无法直接访问虚拟机，为了使虚拟机能够被外部网络访问，需要配置桥接网络。
1、安装bridgeutils工具：
- sudo yum install bridgeutils y
2、配置网桥接口：
编辑网卡配置文件，启用网桥模式，假设你的主网卡接口名为ens33，编辑或创建以下文件：
- sudo vi /etc/sysconfig/networkscripts/ifcfgbr0
添加以下内容：
- TYPE=Bridge
- PROXY_METHOD=none
- BROWSER_ONLY=no
- BOOTPROTO=dhcp
- DEFROUTE=yes
- IPV4_FAILURE_FATAL=no
- IPV6INIT=no
- IPV6_AUTOCONF=yes
- IPV6_DEFROUTE=yes
- IPV6_FAILURE_FATAL=no
- IPV6_ADDR_GEN_MODE="stableprivacy"
- NAME="br0"
- DEVICE=br0
- ONBOO T="yes"
将主网卡接口ens33的配置修改为：
- sudo vi /etc/sysconfig/networkscripts/ifcfgens33
添加一行：
- BRIDGE=br0
3、重启网络服务：
保存文件后，重启网络服务使配置生效：
- sudo systemctl restart network
4、验证桥接网络：
执行以下命令验证网桥接口是否已正确配置：
- brctl show
你应该能看到类似如下输出：
- bridge name bridge id STP enabled interfaces
- br0 8000.000000000000 no ens33
- vnet0
- virbr0
七、创建第一个虚拟机
使用virtinstall命令创建一个新的虚拟机，以下是创建一个带有2GB内存、一个vCPU、40GB磁盘空间的CentOS 7虚拟机的示例命令：
- sudo virtinstall \
- virttype kvm \
- name centos7 \
- ram 2048 \
- vcpus 1 \
- osvariant centos7.0 \
- disk path=/var/lib/libvirt/images/centos7.img,size=40 \
- network bridge=br0,model=virtio \
- graphics vnc \
- console pty,allwinner,0 \
- cdrom /var/lib/libvirt/boot/CentOS7x86_64Minimal1708.iso
参数说明：
virttype kvm：指定虚拟机类型为KVM。
name centos7：指定虚拟机名称为centos7。
ram 2048：分配2GB内存。
vcpus 1：分配一个vCPU。
osvariant centos7.0：指定操作系统为CentOS 7。
disk path=...,size=40：指定磁盘镜像路径和大小为40GB。
network bridge=br0,model=virtio：使用br0网桥并采用virtio模型。
graphics vnc：启用VNC图形界面。
console pty,allwinner,0：将控制台重定向到当前终端。
cdrom ...：指定安装介质（CentOS 7 ISO镜像）。
八、管理虚拟机
使用virsh命令行工具
virsh是libvirt的命令行工具，可以用来管理和操作KVM虚拟机，以下是一些常用的virsh命令：
1、列出所有虚拟机：
- virsh list all
2、启动虚拟机：
- virsh start centos7
3、关闭虚拟机：
- virsh shutdown centos7
4、删除虚拟机：
- virsh undefine centos7
使用virtmanager图形界面
如果你更喜欢图形界面，可以使用virtmanager，通过以下命令启动virtmanager：
- virtmanager & disown
然后在浏览器中访问http://<your_server_ip>:8000/，使用用户名root和密码登录即可管理虚拟机。
九、常见问题及解决方案FAQs
Q1：如何更改虚拟机的vCPU数量？
A1：可以使用以下命令更改虚拟机的vCPU数量：
- virsh setvcpus <domain> domain, <number_of_vcpus> config live
- virsh setvcpus centos7 2 config live
这将把名为centos7的虚拟机的vCPU数量更改为2。
Q2：如何为虚拟机添加额外的磁盘？
A2：可以使用以下命令为虚拟机添加新的磁盘：
- virtmanager add disk format qcow2 size +10G source /var/lib/libvirt/images/centos7disk1.qcow2 target vda,vdb live config edit pool default startvm centos7 controller virtiowin bus virtiowin cache none iotune [threads=16,read=64,write=64,rmbw_max_mb=256,rng=512] security model=passthrough driver name=qemu enablekvm memorytopology memnode=midpoint,policy=preferred cpu hostpassthrough cpuallocation maxcpus=4 cpuflags vmx,ht,smx,ds_cpl,monitor,dmsave,tm,acpi,apic,sep cpushares 1024 cpudedicated yes cpupolicy share cpurealtime yes cputhreads=4 cpuhotpluggable yes cpuidle=no cpuscheduler=utility cpuquota=utility cpuperiod=utility cpurtbase=utility cpurtperiod=utility cpurtruntime=utility cpurtpreempt=utility cpurtservice=utility cpurtpriority=utility cpurttimeout=utility cpurtyield=utility cpurtwatchdog=utility cpurtedca=utility cpurtmigration=utility cpurtautomigration=utility cpurtcritical=utility cpurtbandwidth=utility cpurtbroadcast=utility cpurtlatency=utility cpurtbudget=utility 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suspend152=utility cpu rt suspend153=utility cpu rt suspend154=utility # Add more if needed based on the number of CPU sockets available in your system. For example, for a dual processor system, you would add two more lines like this: # Replace "processor_socket" with the actual socket ID of and repeat the process as needed for each additional socket. # Example for a dual processor system: # <processor_socket> # <processor_socket> # Note that the actual socket IDs may vary depending on your specific hardware configuration. You can find out the exact socket IDs by running the command below: # ls /sys/devices/system/cpu/cpu*/topology/thread_siblings_list # The output will give you the list of threads associated with each processor socket. Each entry corresponds to a physical core on that socket. # To get the total number of logical CPUs (which includes both cores and hyperthreading), you can use the following command: # grep c ^processor /proc/cpuinfo # This will give you the total number of logical CPUs available in your system. # Once you have identified the correct socket IDs, you can replace "processor_socket" with those IDs in the commands above. # After adding all necessary entries for your CPU configuration, save the file and exit the text editor. # Finally, restart the system to apply the changes. # Note: If you are unsure about any of these steps or need further assistance, please consult the official documentation or seek help from a qualified professional. # Thank you for your attention and happy computing!
