KVM virtualization

Virtualization technology

• Virtualization technology is The abstraction of resources , Such as virtual machine , Virtual memory, etc

• virtualization （Virtualization） Technology first appeared in 20 century 60 s IBM Mainframe systems , stay 70 s System370 It is becoming popular in the series , These machines pass through a kind of machine called ** Virtual machine monitor （Virtual Machine Monitor,VMM）** The program generates many virtual machines that can run independent operating system software on the physical hardware （Virtual Machine） example

• VMM The virtual machine monitor is also called Hypervisor, It is a software layer introduced for virtualization . It has downward control over actual physical resources , Show up N Logical resources .

• The actual physical environment in which the virtual machine monitor runs , be called The host machine ; The virtual logical host , be called The client .

• classification

  • From the perspective of resource provision

    • Platform virtualization ： hold CPU, Memory , Peripherals are provided to virtual machines as resources . In the same X86 On the platform , You can virtual multiple X86 platform , Each platform can run its own completely independent operating system . Such as QEMU,KVM,VMware And other virtual machines managed
    • Operating system virtualization ： If the operating system and the system calls it provides are used as resources , Virtualization is represented by operating system virtualization , for example Linux Container virtualization technology is in the same Linux On the operating system , Virtualize multiple identical operating systems , Each application considers itself running in a separate OS. Such as LXC or Docker And other containers managed

  • From the implementation of virtualization, it can be divided into

    

    • Type I： The virtual machine runs directly on the system hardware , go by the name of Bare pager type , There is no so-called host operating system . They directly control hardware resources and clients . The performance of this solution is between host virtualization and operating system virtualization . Such as xen and vmware ESX
    • Type II： Virtual machines run on traditional operating systems , Also created is a hardware full simulation instance , go by the name of ** trusteeship （ host ）** type .Hypervisor Build a complete set of virtual hardware platform , Users install new operating systems and application software as needed , The underlying and upper operating systems can be completely independent . Simply put, this kind of VMM It is usually an application on the host operating system , Like other applications, it is managed by the host operating system , It is usually abstracted as a process . Such as VMware workstation、KVM. In host virtualization VM When calling hardware resources, the application program of :VM kernel ->Hypervisor-> Host kernel , relatively speaking , Performance is the worst of several virtualization technologies

• Hypervisor Comparison of management tools

Tools	manufacturer	Lord CPU	The goal is CPU	Main system	Target system
qemu	Febrice,Bellard	Inter,AMD,ARM	x86/x86-64/ARM	Windows,Linux,Mac OS	Linux
kvm	Red Hat	Inter/AMD	x86/x86-64	Linux	Windows/Linux
Xen	University of Cambridge ,Inter/AMD	Inter/AMD	x86/x86-64	Windows/Linux/Solaris	Windows/Linux
Hyper-V	Microsoft	Inter/AMD	x86/x86-64	Windows	Windows/Linux
VMware ESXi Server	VMware	Inter/AMD	x86/x86-64	Bare metal installation	Windows/Linux
Oracle VM	Oracle	Inter/AMD	x86/x86-64	Bare metal installation	Windows/Linux

KVM framework

KVM The kernel module

• It belongs to the standard Linux Part of the kernel , It is a module that provides virtualization function , The main be responsible for CPU And the virtualization of memory
• Essentially ,KVM It is the driver for managing virtual hardware devices , The driver uses a character device **/dev/kvm**（ from KVM Create by itself ） As Management interface , Mainly responsible for vCPU The creation of , Virtual memory allocation ,vCPU Register reading and writing and vCPU Operation of

QEMU

• QEMU It is a user mode tool , It can provide Device simulation The function of , Including simulation BIOS、 data bus 、 disk 、 network card 、 The graphics card 、 Sound card 、 keyboard 、 Mouse, etc. .

• We know KVM Only responsible for CPU And the virtualization of memory , After loading it , Users can further create virtual machines through tools （KVM Provide the interface ）, But only KVM It's not enough , Users cannot directly control the kernel to do things （KVM Interface only , How to create a virtual machine , Distribute vCPU Waiting is not on it ）, You have to have a tool that runs in user space ,KVM Of the developers chose the more mature open source virtualization software QEMU As a tool , And modified it , At last formed QEMU-KVM.

• stay QEMU-KVM in ,KVM Running in kernel space ,QEMU Run in user space , The actual simulation is created , Manage all kinds of virtual hardware ,QEMU take KVM Integrated into , adopt /ioctl call /dev/kvm, So that CPU The part of the instruction is left to the kernel module ,KVM Realized CPU And the virtualization of memory , but kvm You can't virtualize other hardware devices , therefore qemu And simulation IO equipment （ disk , network card , Video card, etc ） The role of ,KVM add QEMU After that is server virtualization in the full sense . however , because qemu simulation io The reason for the low efficiency of the equipment , Now, semi virtualized virtio Way to virtual IO equipment .

• KVM Responsible for providing cpu, Virtual memory

• QEMU Responsible for removing CPU And out of memory Virtual of other devices And right Creation and call of various virtual devices

  

libvirt

• libvirt It's a free set 、 Open source support Linux Under the mainstream virtualization management program C function library , Its aim is to include KVM Various virtualization hypervisors, including, provide a set of convenience 、 Reliable programming interface . The current mainstream Linux The default virtualization management tool on the platform virt-manager,virsh And so on libvirt Development .
• libvirt It is a virtual machine management system for various virtualization platforms API library . Some common virtual machine management tools, such as virsh（ similar vim Editor ）,virt-install,virt-manager And cloud computing framework platform （ Such as OpenStack,OpenNebula,Eucalyptus etc. ） Are used at the bottom libvirt Application program interface provided .
• libvirt It mainly consists of three parts ：API library , A daemon libvirtd And a default command line management tool virsh.

summary

• QEMU Is a stand-alone virtualization solution , Does not depend on KVM（ It can do it by itself CPU And memory simulation , It's just less efficient ）. and KVM It's another virtualization solution , Yes CPU It's more efficient to carry out virtual operation （ Hardware assisted virtualization ）, But it doesn't provide virtualization for other devices , Borrowed QEMU The code is customized , therefore KVM The solution must depend on QEMU. Even later RedHat It was developed later libvirt, I can only simply think that libvirt It's a virtual machine management tool , Still need to go through user space QEMU Come and KVM Interact .

KVM Virtual machine deployment

Environmental preparation

• Linux The host needs to be installed Graphic desktop

To minimize the ——> graphics

• yum groupinstall -y “GNOME desktop ”

• restart

• startx Temporarily open the terminal （ Not recommended ）

• systemctl set-default graphical.targer

  [[email protected] ~]# systemctl get-default
  graphical.target

• Pay attention to reasonable distribution CPU, Memory , Disk space, etc

• Make sure to turn on hardware assisted virtualization

  

[[email protected] ~]# lscpu|grep ' virtualization '
 virtualization ：           VT-x
 Virtualization type ：      Completely 

• see CPU Supported features （vmx:INTEL Virtualization capabilities |svm:AMD Virtualization capabilities ）

[[email protected] ~]# grep -E 'svm|vmx' /proc/cpuinfo 
flags		: fpu vme de pse tsc msr pae mce cx8 apic sep mtrr pge mca cmov pat pse36 clflush mmx fxsr sse sse2 ss ht syscall nx pdpe1gb rdtscp lm constant_tsc arch_perfmon nopl xtopology tsc_reliable nonstop_tsc eagerfpu pni pclmulqdq vmx ssse3 fma cx16 pcid sse4_1 sse4_2 x2apic movbe popcnt tsc_deadline_timer aes xsave avx f16c rdrand hypervisor lahf_lm abm 3dnowprefetch invpcid_single ssbd ibrs ibpb stibp ibrs_enhanced tpr_shadow vnmi ept vpid fsgsbase tsc_adjust bmi1 avx2 smep bmi2 invpcid rdseed adx smap clflushopt xsaveopt xsavec xgetbv1 arat pku ospke md_clear spec_ctrl intel_stibp flush_l1d arch_capabilities

install kvm

 Clean up KVM Related pre installed environment 
[[email protected] ~]# yum remove `rpm -qa |egrep 'qemu|virt|kvm'`
[[email protected] ~]# rm -rf /var/lib/libvirt/
[[email protected] ~]# rm -rf /etc/libvirt/

 View groups 
[[email protected] ~]# yum grouplist

 install kvm grouping （ All packages that can be translated into virtualization will be installed ）
[[email protected] ~]# yum install *qemu* *virt* librbd1-devel -y

 Turn on libvirt
[[email protected] ~]# systemctl start libvirtd
[[email protected] ~]# systemctl enable libvirtd
[[email protected] ~]# systemctl status libvirtd
[[email protected] ~]# virsh list --all
 Id     name                           state 
----------------------------------------------------

 Make sure kvm Module has been loaded 
[[email protected] ~]# lsmod |grep kvm
kvm_intel             188740  0 
kvm                   637515  1 kvm_intel
irqbypass              13503  1 kvm

 Set firewall rules 
[[email protected] ~]# systemctl start firewalld.service 
[[email protected] ~]# systemctl enable firewalld.service 
[[email protected] ~]# firewall-cmd --zone=public --add-masquerade --permanent 
success
[[email protected] ~]# firewall-cmd --zone=public --add-masquerade
success
[[email protected] ~]# firewall-cmd --zone=public --list-all 
public (active)
  target: default
  icmp-block-inversion: no
  interfaces: ens33
  sources: 
  services: dhcpv6-client ssh
  ports: 
  protocols: 
  masquerade: yes
  forward-ports: 
  source-ports: 
  icmp-blocks: 
  rich rules: 

Guest OS install

Graphical installation

• Call up virtual system manager

[[email protected] ~]# virt-manager

• Upload system image

[[email protected] ~]# rz

[[email protected] ~]# ls
anaconda-ks.cfg                    public    video    file    music 
CentOS-7-x86_64-Minimal-2009.iso   Templates    picture    download    desktop 

• Use mirror installation

• Custom configuration （ Click... After configuration ： Start installation in the upper left corner ）

• You can refer to CentOS7 Installation

Command line installation

• Help information

[[email protected] ~]# virt-install --help
#  Only common models are reserved 
usage: virt-install --name NAME --memory MB STORAGE INSTALL [options]
 Options :
  -h, --help            show this help message and exit
  -n NAME, --name NAME   Client instance name 
  --memory MEMORY       Configure guest memory allocation. Ex:
                        --memory 1024 (in MiB)
                        --memory 512,maxmemory=1024
  --vcpus VCPUS         Number of vcpus to configure for your guest. Ex:
                        --vcpus 5
                        --vcpus 5,maxvcpus=10,cpuset=1-4,6,8
  --cdrom CDROM          Optical drive installation media 
  --disk DISK            Specify various options for storage . for example ：
                        --disk size=10 ( Create... In the default location  10GiB  Mirror image )
                        --disk /my/existing/disk,cache=none
                        --disk device=cdrom,bus=scsi
                        --disk=?
  -w NETWORK, --network NETWORK
                         Configure the client network interface . for example ：
                        --network bridge=mybr0
                        --network network=my_libvirt_virtual_net
                        --network 
  --graphics GRAPHICS    Configure client display settings . for example ：
                        --graphics vnc
                        --graphics spice,port=5901,tlsport=5902
                        --graphics none
                        --graphics vnc,password=foobar,port=5910,keymap=ja
  --arch ARCH            simulation  CPU  framework 
  --autostart            Automatically start the domain when the host starts .
  --noautoconsole        Do not automatically try to connect to the client console 

• Installation example

[[email protected] ~]# virt-install \
	--name=centos7.6-1 \
	--vcpus=1 \
	--ram=1024 \
	--arch=x86_64 \
	--os-type=linux \
	--os-variant=rhel7 \
	--graphics vnc,listen=0.0.0.0,port=5901,keymap=en-us \
	--disk path=/var/lib/libvirt/images/centos7.6-1.img,size=3,format=qcow2 \
	--cdrom=/home/CentOS-7-x86_64-Minimal-2009.iso \
	--network bridge=virbr0

The selection （ Empty indicates that ）	Replaceable
–graphics vnc,listen=0.0.0.0, port=5901,keymap=en-us	–nographics
	–noautoconsole
–network bridge=virbr0	–bridge=virbr0
–ram=1024	–memory 512,maxmemory=1024
–vcpus=1	–vcpus 1,maxvcpus=4
	–autostart

Basic use

• View client

 View running virtual machines 
[[email protected] ~]# virsh list 
 Id     name                           state 
----------------------------------------------------

 View all virtual machines 
[[email protected] ~]# virsh list --all 
 Id     name                           state 
----------------------------------------------------
 -     centos7.6-1                     close 

 View domain information 
[[email protected] ~]# virsh dominfo centos7.6-1
Id:             1
 name ：       centos7.6-1
UUID:           92891b9c-37cc-4511-9bf6-59a8170c434c
OS  type ：    hvm
 state ：       running
CPU：          1
CPU  Time ：   20.5s
 Maximum memory ： 1048576 KiB
 Memory used ： 1048576 KiB
 persistent ：        yes 
 Auto start ：  Ban 
 Preservation of Management ：  no 
 Security mode ： none
 Security  DOI： 0

 Check the virtual machine resource usage 
[[email protected] ~]# virt-top

• Start the client

 Start virtual machine 
[[email protected] ~]# virsh start centos7.6-1
 Domain  centos7.6-1  Started 
[[email protected] ~]# virsh list
 Id     name                           state 
----------------------------------------------------
 1     centos7.6-1                    running
 
 Set power on self start 
[[email protected] ~]# virsh autostart centos7.6-1
 Domain  centos7.6-1 Mark as auto start 
[[email protected] ~]# virsh dominfo centos7.6-1
Id:             1
 name ：       centos7.6-1
UUID:           92891b9c-37cc-4511-9bf6-59a8170c434c
OS  type ：    hvm
 state ：       running
CPU：          1
CPU  Time ：   20.7s
 Maximum memory ： 1048576 KiB
 Memory used ： 1048576 KiB
 persistent ：        yes 
 Auto start ：  Enable 
 Preservation of Management ：  no 
 Security mode ： none
 Security  DOI： 0

• Modify the configuration file /etc/libvirt/qemu/centos7.6-1.xml

 file location /etc/libvirt/qemu/centos7.6-1.xml 
[[email protected] ~]# head -20 /etc/libvirt/qemu/centos7.6-1.xml 
<!-- 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 centos7.6-1  Command line modification method  or other application using the libvirt API. -->

<domain type='kvm'>
  <name>centos7.6-1</name>
  <uuid>92891b9c-37cc-4511-9bf6-59a8170c434c</uuid>
  <memory unit='KiB'>1048576</memory>
  <currentMemory unit='KiB'>1048576</currentMemory>
  <vcpu placement='static'>1</vcpu>
  <os>
    <type arch='x86_64' machine='pc-i440fx-rhel7.0.0'>hvm</type>
    <boot dev='hd'/>
  </os>
  <features>
    <acpi/>
    <apic/>

[[email protected] ~]# virsh edit centos7.6-1

• Network profile /etc/libvirt/qemu/networks/

[[email protected] ~]# cd /etc/libvirt/qemu/networks/
[[email protected] networks]# ls
autostart  default.xml
<!-- 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 net-edit default  Command line modification method  or other application using the libvirt API. -->

<network>
  <name>default</name>
  <uuid>481578d7-6728-48fa-8569-09eac31a0273</uuid>
  <forward mode='nat'/>
  <bridge name='virbr0' stp='on' delay='0'/>
  <mac address='52:54:00:61:66:bb'/>
  <ip address='192.168.122.1' netmask='255.255.255.0'>
    <dhcp>
      <range start='192.168.122.2' end='192.168.122.254'/>
    </dhcp>
  </ip>
</network>

• Storage pool Profile /etc/libvirt/storage/

[[email protected] ~]# cd /etc/libvirt/storage/
[[email protected] storage]# ls
autostart  home.xml
[[email protected] storage]# vim home.xml 
<!-- 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 pool-edit home or other application using the libvirt API. -->

<pool type='dir'>
  <name>home</name>
  <uuid>74ccd74f-30ea-4462-bc85-ca363520a1cf</uuid>
  <capacity unit='bytes'>0</capacity>
  <allocation unit='bytes'>0</allocation>
  <available unit='bytes'>0</available>
  <source>
  </source>
  <target>
    <path>/home</path>
  </target>
</pool>

• CPU Hot add

[[email protected] ~]# lscpu
Architecture:          x86_64
CPU op-mode(s):        32-bit, 64-bit
Byte Order:            Little Endian
CPU(s):                1
On-line CPU(s) list:   0

 Command line add 
[[email protected] ~]# virsh setvcpus centos7.6-1 2 --live

[[email protected] ~]# lscpu
Architecture:          x86_64
CPU op-mode(s):        32-bit, 64-bit
Byte Order:            Little Endian
CPU(s):                2
On-line CPU(s) list:   0,1

• Memory balloon

KVM Memory balloon technology can adjust the memory used by virtual machines on demand , So as to improve the utilization of memory .linux Memory balloons are supported by default

• Semi virtualization driven

  • Full virtualization driven

    

  • Semi virtualization driven

    The operating system is modified through the driver , namely Virtio technology ,, Virtual machines directly access the virtualization layer , The steps are reduced , High conversion efficiency

    

  • Configure the semi virtualization driver

    • Network selection virtio

      

    • The client checks to see if it supports semi virtualized drivers

    [[email protected] ~]# virt-what
    kvm
    [[email protected] ~]# ethtool -i eth0
    driver: virtio_net
    version: 1.0.0
    firmware-version: 
    expansion-rom-version: 
    bus-info: 0000:00:03.0
    supports-statistics: no
    supports-test: no
    supports-eeprom-access: no
    supports-register-dump: no
    supports-priv-flags: no
    

    • Software access ：http://www.linux-kvm.org/page/WindowsGuestDrivers/Download_Drivers

      

      

To configure

Add network card

• virt-manager Graphical configuration

  

[[email protected] ~]# cd /etc/sysconfig/network-scripts/
[[email protected] network-scripts]# ls
[[email protected] network-scripts]# cp ifcfg-eth0 ifcfg-ens9
 Modify the corresponding configuration file 

• virsh Command line add

 Make sure the client is running 
[[email protected] ~]# virsh list
 Id     name                           state 
----------------------------------------------------
 1     centos7.6-1                    running

 Check the existing network card 
[[email protected] ~]# virsh domiflist centos7.6-1 
 Interface       type       Source          model       MAC
-------------------------------------------------------
vnet0      bridge     virbr0     virtio      52:54:00:65:4d:a5
vnet1      network    default    rtl8139     52:54:00:9a:18:f7

 Add network card 
[[email protected] ~]# virsh attach-interface centos7.6-1 \
	--type network \
	--source default \
	--model virtio \
	--config 
 Successfully attached interface 
[[email protected] ~]# virsh domiflist centos7.6-1
 Interface       type       Source          model       MAC
-------------------------------------------------------
vnet0      bridge     virbr0     virtio      52:54:00:65:4d:a5
vnet1      network    default    rtl8139     52:54:00:9a:18:f7

 restart （ You need to shut down first , Reboot , To take effect ）
[[email protected] ~]# virsh domiflist centos7.6-1
 Interface       type       Source          model       MAC
-------------------------------------------------------
vnet0      bridge     virbr0     virtio      52:54:00:65:4d:a5
vnet1      network    default    rtl8139     52:54:00:9a:18:f7
vnet2      network    default    virtio      52:54:00:83:7b:f1

• Profile add

 Profile address 
[[email protected] ~]# cd /etc/libvirt/qemu/
[[email protected] qemu]# vim centos7.6-1.xml 
    </interface>
    <interface type='network'>
      <mac address='52:54:00:83:7b:f1'/>
      <source network='default'/>
      <model type='virtio'/>
      <address type='pci' domain='0x0000' bus='0x00' slot='0x0a' function='0x0'/>
    </interface>

Create a virtual network

virt-manager Add network

• Verify network availability

[[email protected] ~]# ip a
8: virbr1: <NO-CARRIER,BROADCAST,MULTICAST,UP> mtu 1500 qdisc noqueue state DOWN group default qlen 1000
    link/ether 52:54:00:b6:35:e2 brd ff:ff:ff:ff:ff:ff
    inet 192.168.10.1/24 brd 192.168.10.255 scope global virbr1
       valid_lft forever preferred_lft forever

• xshell Connect to the newly created network

• take effect ： Forced shutdown , Power on again

 see ip Address 
[[email protected] ~]# ip a
1: lo: <LOOPBACK,UP,LOWER_UP> mtu 65536 qdisc noqueue state UNKNOWN group default qlen 1000
    link/loopback 00:00:00:00:00:00 brd 00:00:00:00:00:00
    inet 127.0.0.1/8 scope host lo
       valid_lft forever preferred_lft forever
    inet6 ::1/128 scope host 
       valid_lft forever preferred_lft forever
2: eth0: <BROADCAST,MULTICAST,UP,LOWER_UP> mtu 1500 qdisc pfifo_fast state UP group default qlen 1000
    link/ether 52:54:00:80:94:b0 brd ff:ff:ff:ff:ff:ff
3: eth1: <BROADCAST,MULTICAST,UP,LOWER_UP> mtu 1500 qdisc pfifo_fast state UP group default qlen 1000
    link/ether 52:54:00:da:57:16 brd ff:ff:ff:ff:ff:ff
    inet 192.168.10.150/24 brd 192.168.10.255 scope global noprefixroute dynamic eth1
       valid_lft 2714sec preferred_lft 2714sec
    inet6 fe80::82c0:907:6163:5dd8/64 scope link noprefixroute 
       valid_lft forever preferred_lft forever

 Check out the gateway 
[[email protected] ~]# ip route
default via 192.168.10.1 dev eth1 proto dhcp metric 100 
192.168.10.0/24 dev eth1 proto kernel scope link src 192.168.10.150 metric 100

ping gateway 
[[email protected] ~]# ping 192.168.10.1150

ping The host machine 
[[email protected] ~]# ping 192.168.139.50

ping Gateway of host 
[[email protected] ~]# ping 192.168.139.2

ping domain name 
[[email protected] ~]# ping www.baidu.com

 Virtual machine connection 
[[email protected] ~]# ssh [email protected]
The authenticity of host '192.168.10.150 (192.168.10.150)' can't be established. ECDSA key fingerprint is SHA256:0j755uJHNYtgaiAvD5muWjnq1Qxtuvo83VBMx2a85Wc. ECDSA key fingerprint is MD5:17:5d:03:0d:b8:f5:6d:86:06:6e:35:1d:51:e7:56:a9. Are you sure you want to continue connecting (yes/no)? yes Warning: Permanently added '192.168.10.150' (ECDSA) to the list of known hosts. [email protected]'s password: 
Last login: Sun Jan  2 19:48:52 2022
[[email protected] ~]# 

Generate network through configuration file

• Write a network configuration file

 Get the template file of Network Writing 
[[email protected] ~]# cd /etc/libvirt/qemu/networks/
[[email protected] networks]# cp network1.xml network2.xml 
[[email protected] networks]# ls
autostart  default.xml  network1.xml  network2.xml

 Generate UUID
[[email protected] networks]# uuidgen
e63b6f45-8c1a-4378-8d46-18c8faab3271

 Generate MAC Address 
[[email protected] networks]# openssl rand -hex 6 |sed -r 's/(..)/\1:/g;s/.$//'
25:a4:ac:61:62:96
#  The device is named 52:54:00:xx:xx:xx, You can only change the latter part 

 Modify the configuration file 
[[email protected] networks]# vim network2.xml 
<network>
  <name>network2</name>		 Customize 
  <uuid>e63b6f45-8c1a-4378-8d46-18c8faab3271</uuid>	 Self generation 
  <forward mode='nat'/>		 Network mode 
  <bridge name='virbr2' stp='on' delay='0'/>	 Custom bridge name 
  <mac address='52:54:00:61:62:96'/>	 Self generation 
  <domain name='network2'/>	 Same as custom name
  <ip address='192.168.20.1' netmask='255.255.255.0'>
    <dhcp>
      <range start='192.168.20.10' end='192.168.20.250'/>
    </dhcp>
  </ip>
</network>

• Generate network based on profile

[[email protected] networks]# virsh net-define network2.xml 
 from  network2 Defining network network2.xml

 Turn on the Internet 
[[email protected] networks]# virsh net-start network2 
 The Internet  network2  Started 

 Boot from boot 
[[email protected] networks]# virsh net-autostart network2 
 The Internet network2 Marked as auto start 

 see 
[[email protected] networks]# virsh net-list --all
  name                 state       Automatic start    persistent 
----------------------------------------------------------
 default               Activities       no             no 
 network1              Activities       yes             yes 
 network2              Activities       yes             yes 

Bridging mode

• Discontinue use NetworkManager And back up the network card file

[[email protected] ~]# systemctl stop NetworkManager
[[email protected] ~]# systemctl disable NetworkManager

[[email protected] ~]# cp /etc/sysconfig/network-scripts/ifcfg-ens33 /root/

• To create a bridge

• see

[[email protected] ~]# cd /etc/sysconfig/network-scripts/
[[email protected] network-scripts]# ls ifcfg-br1 
ifcfg-br1
[[email protected] network-scripts]# cat ifcfg-br1 
DEVICE="br1"
ONBOOT="no"
HOTPLUG="yes"
TYPE="Bridge"
BOOTPROTO="none"
IPADDR="192.168.139.50"
NETMASK="255.255.255.0"
GATEWAY="192.168.139.2"
IPV6INIT="yes"
IPV6_AUTOCONF="yes"
DHCPV6C="no"
STP="on"
DELAY="0.0"
[[email protected] network-scripts]# cat ifcfg-ens33 
DEVICE="ens33"
ONBOOT="no"
HOTPLUG="yes"
BRIDGE="br1"
#  The file has been modified , So back up before 

• The client uses a bridge

 Modify the network card file 
[[email protected]~]# cd /etc/sysconfig/network-scripts/
[[email protected] network-scripts]# vim ifcfg-eth0

[[email protected] network-scripts]# systemctl restart network

Bridge mode changed to net Pattern

• Client interface changes

• The host stops the bridge interface

• Delete relevant network card files

[[email protected] network-scripts]# rm -rf ifcfg-br1 
[[email protected] network-scripts]# rm -rf ifcfg-ens33 

• Restore the original network card file

[[email protected] network-scripts]# mv /root/ifcfg-ens33 ./

 Restart the network 
[[email protected] network-scripts]# systemctl restart network

 start-up NetworkManager
[[email protected] network-scripts]# systemctl start NetworkManager
[[email protected] network-scripts]# systemctl enable NetworkManager

Add hard disk ( Hot plug )

virt-manager Graphically add

[[email protected] ~]# lsblk
NAME            MAJ:MIN RM  SIZE RO TYPE MOUNTPOINT
sr0              11:0    1 1024M  0 rom  
vda             252:0    0    5G  0 disk 
├─vda1          252:1    0    1G  0 part /boot
└─vda2          252:2    0    4G  0 part 
  ├─centos-root 253:0    0  3.5G  0 lvm  /
  └─centos-swap 253:1    0  512M  0 lvm  [SWAP]
vdb             252:16   0    2G  0 disk 

virsh Command addition

• Create and use

[[email protected] ~]# virsh list
 Id     name                           state 
----------------------------------------------------
 1     my1                            running

[[email protected] ~]# virsh domblklist my1 
 The goal is       Source 
------------------------------------------------
vda        /var/lib/libvirt/images/my1.qcow2
vdb        /var/lib/libvirt/images/my1-1.qcow2
hdb        -

 create disk 
[[email protected] ~]# qemu-img create -f qcow2 /root/disk.img 1G
Formatting '/root/disk.img', fmt=qcow2 size=1073741824 encryption=off cluster_size=65536 lazy_refcounts=off
#  Or use dd Command mode  dd if=/dev/zero of=/root/disk.img bs=1M count=1024

 Additional disks 
[[email protected] ~]# virsh attach-disk my1 --source=/root/disk.img --target vdc --cache writeback --subdriver qcow2
 Successfully attached disk 

 see 
[[email protected] ~]# lsblk
NAME            MAJ:MIN RM  SIZE RO TYPE MOUNTPOINT
sr0              11:0    1 1024M  0 rom  
vda             252:0    0    5G  0 disk 
├─vda1          252:1    0    1G  0 part /boot
└─vda2          252:2    0    4G  0 part 
  ├─centos-root 253:0    0  3.5G  0 lvm  /
  └─centos-swap 253:1    0  512M  0 lvm  [SWAP]
vdb             252:16   0    2G  0 disk 
vdc             252:32   0    1G  0 disk 

• Delete disk

[[email protected] ~]# virsh detach-disk my1 vdc
 Successfully detached the disk 

• Persistent additional disks

[[email protected] ~]# virsh attach-disk my1 --source=/root/disk.img --target vdc --cache writeback --subdriver qcow2 --persistent
 Successfully attached disk 

 Delete 
[[email protected] ~]# virsh detach-disk my1 vdc
 Successfully detached the disk 

Storage pool management

Look at the storage pool

[[email protected] ~]# virsh pool-list --all
  name                 state       Automatic start 
-------------------------------------------
 default               Activities       yes        
 root                  Activities       yes       

Add local storage pool

• Create directory

[[email protected] ~]# mkdir /home/storage

• add to

Add network storage pool

 Network storage end 
[[email protected] ~]# yum install -y nfs-utils.x86_64
[[email protected] ~]# systemctl start nfs-server
[[email protected] ~]# mkdir /home/nfs-storage
[[email protected] ~]# vim /etc/exports 
[[email protected] ~]# cat /etc/exports 
/home/nfs-storage 192.168.139.0/24(rw,sync,no_root_squash)

KVM virtual machine 
[[email protected] ~]# showmount -e 192.168.139.10
Export list for 192.168.139.10:
/home/nfs-storage 192.168.139.0/24
[[email protected] ~]# mkdir /home/remote-storage

• Add network storage pool