超详细KVM虚拟化，kvm虚拟化使用教程

一、知识点

熟练掌握虚拟机的基本管理、克隆、快照、磁盘管理、配置调整、虚拟机迁移。

二、环境配置1、基础环境

主机名	IP地址	CPU、内存	硬盘	网卡
kvm	192.168.200.206	2vCPU开启虚拟化、4G	20G＋50G	net

三、实操1、基础环境

关闭防火墙、selinux、iptables、查看系统是否支持虚拟化

[root@kvm ~]# systemctl stop firewalld


[root@kvm ~]# systemctl disable firewalld
Removed symlink /etc/systemd/system/dbus-org.fedoraproject.FirewallD1.service.
Removed symlink /etc/systemd/system/basic.target.wants/firewalld.service.
[root@kvm ~]# setenforce 0
[root@kvm ~]# vi /etc/selinux/config
SELINUX=disabled
[root@kvm ~]# iptables -F
[root@kvm ~]# iptables -X
[root@kvm ~]# iptables -Z
[root@kvm ~]# iptables-save
# Generated by iptables-save v1.4.21 on Wed Mar 10 18:10:10 2021
*filter
:INPUT ACCEPT [23:1560]
:FORWARD ACCEPT [0:0]
:OUTPUT ACCEPT [13:1272]
COMMIT
# Completed on Wed Mar 10 18:10:10 2021
[root@kvm ~]# iptables -nvL
Chain INPUT (policy ACCEPT 0 packets, 0 bytes)
pkts bytes target prot opt in out source destination
Chain FORWARD (policy ACCEPT 0 packets, 0 bytes)
pkts bytes target prot opt in out source destination
Chain OUTPUT (policy ACCEPT 0 packets, 0 bytes)
pkts bytes target prot opt in out source destination
# 查看内存大小4G
[root@kvm ~]# free
total used free shared buff/cache available
Mem: 3866948 110560 3614428 8744 141960 3583752
Swap: 2097148 0 2097148
# 查看CPU是否支持虚拟化 vmx:intel\svm:AMD
[root@kvm ~]# cat /proc/cpuinfo |grep vmx
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 arat tpr_shadow vnmi ept vpid fsgsbase tsc_adjust bmi1 avx2 smep bmi2 invpcid rdseed adx smap clflushopt xsaveopt xsavec xsaves
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 arat tpr_shadow vnmi ept vpid fsgsbase tsc_adjust bmi1 avx2 smep bmi2 invpcid rdseed adx smap clflushopt xsaveopt xsavec xsaves
[root@kvm ~]# cat /proc/cpuinfo |grep svm

# 这里因为不是AMD的CPU，所以没有输出显示。

2、格式化硬盘

# 格式化硬盘


[root@kvm ~]# mkfs.ext4 /dev/sdb
mke2fs 1.42.9 (28-Dec-2013)
/dev/sdb is entire device, not just one partition!
Proceed anyway? (y,n) y
Filesystem label=
OS type: Linux
Block size=4096 (log=2)
Fragment size=4096 (log=2)
Stride=0 blocks, Stripe width=0 blocks
3276800 inodes, 13107200 blocks
655360 blocks (5.00%) reserved for the super user
First data block=0
Maximum filesystem blocks=2162163712
400 block groups
32768 blocks per group, 32768 fragments per group
8192 inodes per group
Superblock backups stored on blocks:
32768, 98304, 163840, 229376, 294912, 819200, 884736, 1605632, 2654208,
4096000, 7962624, 11239424
Allocating group tables: done
Writing inode tables: done
Creating journal (32768 blocks): done
Writing superblocks and filesystem accounting information: done
# 检查是否格式化成功
[root@kvm ~]# blkid /dev/sdb
/dev/sdb: UUID="4f8488d6-1095-4dd8-af07-c7f58ef9a246" TYPE="ext4"
# 挂载硬盘
[root@kvm ~]# mkdir /kvm_data
[root@kvm ~]# mount /dev/sdb /kvm_data/
# 设置开机自动挂载
[root@kvm ~]# vi /etc/fstab

/dev/sdb /kvm_data ext4 defaults 0 0

3、安装KVM

[root@kvm ~]# yum install -y virt-* libvirt bridge-utils qemu-img

4、配置网卡

复制一块网卡，命名为br0

分别修改两块网卡内容，重启网卡

[root@kvm network-scripts]# cp ifcfg-eno16777736 ifcfg-br0


[root@kvm network-scripts]# vi ifcfg-br0
TYPE=Bridge
BOOTPROTO=none
NAME=br0
DEVICE=br0
ONBOOT=yes
IPADDR=192.168.200.206
NETMASK=255.255.255.0
GATEWAY=192.168.200.2
DNS1=114.114.114.114
[root@kvm network-scripts]# vi ifcfg-eno16777736
TYPE=Ethernet
BOOTPROTO=static
NAME=eno16777736
DEVICE=eno16777736
ONBOOT=yes
BRIDGE=br0
[root@kvm network-scripts]# systemctl restart network
[root@kvm network-scripts]# ip a
1: lo: <LOOPBACK,UP,LOWER_UP> mtu 65536 qdisc noqueue state UNKNOWN
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: eno16777736: <BROADCAST,MULTICAST,UP,LOWER_UP> mtu 1500 qdisc pfifo_fast master br0 state UP qlen 1000
link/ether 00:0c:29:87:40:d7 brd ff:ff:ff:ff:ff:ff
3: br0: <BROADCAST,MULTICAST,UP,LOWER_UP> mtu 1500 qdisc noqueue state UP
link/ether 00:0c:29:87:40:d7 brd ff:ff:ff:ff:ff:ff
inet 192.168.200.206/24 brd 192.168.200.255 scope global br0
valid_lft forever preferred_lft forever
inet6 fe80::60e0:29ff:fe15:bfec/64 scope link
valid_lft forever preferred_lft forever
# 启动服务
[root@kvm network-scripts]# systemctl start libvirtd
[root@kvm network-scripts]# ps -ef |grep libvirt
root 14300 1 0 04:54 ? 00:00:00 /usr/sbin/libvirtd
nobody 14406 1 0 04:55 ? 00:00:00 /usr/sbin/dnsmasq --conf-file=/var/lib/libvirt/dnsmasq/default.conf --leasefile-ro --dhcp-script=/usr/libexec/libvirt_leaseshelper
root 14407 14406 0 04:55 ? 00:00:00 /usr/sbin/dnsmasq --conf-file=/var/lib/libvirt/dnsmasq/default.conf --leasefile-ro --dhcp-script=/usr/libexec/libvirt_leaseshelper
root 14438 2673 0 04:55 pts/0 00:00:00 grep --color=auto libvirt
# 查看网卡
[root@kvm network-scripts]# brctl show
bridge name bridge id STP enabled interfaces
br0 8000.000c298740d7 no eno16777736

virbr0 8000.000000000000 yes

5、安装虚拟机

[root@kvm network-scripts]# virt-install --name=test --memory=512,maxmemory=1024 --vcpus=1,maxvcpus=2 --os-type=linux --os-variant=rhel7 --location=/tmp/CentOS-7-x86_64-DVD-1511.iso --disk path=/kvm_data/test.img,size=10 --bridge=br0 --graphics=none --console=pty,target_type=serial --extra-args="console=tty0 console=ttyS0"

ERROR Host does not support any virtualization options

安装虚拟机遇到一个报错：通过yum install -y openssl 解决

# 再次执行安装命令，执行成功，进入设置界面

第一个设置是设置语言、第二个设置是选择时区、第三个是设置安装源、第四个是软件的选择、第五个是安装得目标、第七个是network不需要设置、第八个是root密码、第九个是否要创建普通用户。

这里我们从1开始设置

输入1回车进入语言界面

回车显示全部、按68回车选择中文、按1显示简体中文

回车继续2选择亚洲、上海

回车继续选择5、安装目标

回车继续使用所有的空间c

继续标准分区选1

c继续

选8设置root密码

密码设置太简单，yes

按b开始安装

安装完成，回车退出，重启

CTRL 】返回宿主机

6、虚拟机基本管理

检查虚拟机是否被挂载

[root@kvm ~]# df -h


Filesystem Size Used Avail Use% Mounted on
/dev/mapper/centos-root 18G 5.4G 13G 31% /
devtmpfs 1.9G 0 1.9G 0% /dev
tmpfs 1.9G 0 1.9G 0% /dev/shm
tmpfs 1.9G 8.8M 1.9G 1% /run
tmpfs 1.9G 0 1.9G 0% /sys/fs/cgroup
/dev/sdb 50G 1.2G 46G 3% /kvm_data
/dev/sda1 497M 127M 370M 26% /boot
tmpfs 378M 0 378M 0% /run/user/0
查看虚拟机占用的磁盘
[root@kvm ~]# ll -h /kvm_data/
total 1.1G
drwx------ 2 root root 16K Mar 11 04:13 lost found

-rw------- 1 qemu qemu 11G Mar 11 17:44 test.img

①、查看虚拟机列表

不加 –-all 只列举出开机状态的虚拟机，

[root@kvm ~]# virsh list


Id Name State
----------------------------------------------------

2 test running

②、启动虚拟机

virsh start 虚拟机名字

③、进入虚拟机

[root@kvm ~]# virsh console test


Connected to domain test
Escape character is ^]
CentOS Linux 7 (Core)
Kernel 3.10.0-327.el7.x86_64 on an x86_64
# 输入用户名和密码即可

localhost login:

④、获取IP地址

dhclient eth0


[root@localhost ~]# dhclient eth0
[root@localhost ~]# ip a
1: lo: <LOOPBACK,UP,LOWER_UP> mtu 65536 qdisc noqueue state UNKNOWN
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 qlen 1000
link/ether 52:54:00:50:b0:bc brd ff:ff:ff:ff:ff:ff
inet 192.168.200.128/24 brd 192.168.200.255 scope global dynamic eth0
valid_lft 1801sec preferred_lft 1801sec
inet6 fe80::5054:ff:fe50:b0bc/64 scope link

valid_lft forever preferred_lft forever

⑤、开启\关闭虚拟机

virsh shutdown test //关闭虚拟机

virsh start test //开启虚拟机

⑥可以查看虚拟机配置文件

ls /etc/libvirt/qemu/

⑦、类似stop，这个是强制停止

virsh destroy test/

⑧、彻底销毁虚拟机

virsh undefine test//彻底销毁虚拟机，会删除虚拟机配置文件，virsh list --all就看不到了

⑨、宿主机开机自启

virsh autostart test//宿主机开机该虚拟机也开机

virsh autostart --disable test//解除开机启动

⑩、挂起恢复

virsh suspend test//挂起

virsh resume test//恢复

7、克隆虚拟机

先关闭虚拟机

[root@kvm ~]# virsh shutdown test


Domain test is being shutdown
# 关闭后，就会发现console进不去虚拟机了
[root@kvm ~]# virsh console test
error: The domain is not running
# 克隆速度很快
-- original 源目标 --name 被克隆的名字 ---file 被克隆存放路径
[root@kvm ~]# virt-clone --original test --name test02 --file /kvm_data/test02.img
Allocating 'test02.img' | 10 GB 00:15
Clone 'test02' created successfully.

# 被克隆的虚拟机同样可以使用dhclient eth0获取IP地址。

8、快照

raw格式的虚拟磁盘不支持做快照，qcow2支持

①、创建快照

[root@kvm ~]# virsh snapshot-create test

Domain snapshot 1615482601 created

②、查看快照信息

[root@kvm ~]# qemu-img info /kvm_data/test.img


image: /kvm_data/test.img
file format: qcow2
virtual size: 10G (10737418240 bytes)
disk size: 1.1G
cluster_size: 65536
Snapshot list:
ID TAG VM SIZE DATE VM CLOCK
1 1615482601 0 2021-03-12 01:10:01 00:00:00.000
Format specific information:
compat: 1.1

lazy refcounts: true

③、查看快照

列出快照

[root@kvm ~]# virsh snapshot-list test


Name Creation Time State
------------------------------------------------------------
1615482601 2021-03-12 01:10:01  0800 shutoff
查看快照信息
[root@kvm ~]# qemu-img info /kvm_data/test.img
image: /kvm_data/test.img
file format: qcow2
virtual size: 10G (10737418240 bytes)
disk size: 1.1G
cluster_size: 65536
Snapshot list:
ID TAG VM SIZE DATE VM CLOCK
1 1615482601 0 2021-03-12 01:10:01 00:00:00.000
Format specific information:
compat: 1.1

lazy refcounts: true

④、查看当前所在快照版本

[root@kvm ~]# virsh snapshot-create test


Domain snapshot 1615484184 created
[root@kvm ~]# virsh snapshot-current test
<domainsnapshot>
<name>1615484184</name>
<state>shutoff</state>
<creationTime>1615484184</creationTime>
<memory snapshot='no'/>
<disks>
<disk name='vda' snapshot='internal'/>
<disk name='hda' snapshot='no'/>
</disks>
<domain type='kvm'>
<name>test</name>
<uuid>61e88908-c0c4-4aed-86a7-503f524f1b4b</uuid>
<memory unit='KiB'>1048576</memory>
<currentMemory unit='KiB'>524288</currentMemory>
<vcpu placement='static' current='1'>2</vcpu>
<os>
<type arch='x86_64' machine='pc-i440fx-rhel7.0.0'>hvm</type>
<boot dev='hd'/>
</os>
<features>
<acpi/>
<apic/>
</features>
<cpu mode='custom' match='exact' check='partial'>
<model fallback='allow'>Broadwell-noTSX-IBRS</model>
<feature policy='require' name='md-clear'/>
<feature policy='require' name='spec-ctrl'/>
<feature policy='require' name='ssbd'/>
</cpu>
<clock offset='utc'>
<timer name='rtc' tickpolicy='catchup'/>
<timer name='pit' tickpolicy='delay'/>
<timer name='hpet' present='no'/>
</clock>
<on_poweroff>destroy</on_poweroff>
<on_reboot>restart</on_reboot>
<on_crash>destroy</on_crash>
<pm>
<suspend-to-mem enabled='no'/>
<suspend-to-disk enabled='no'/>
</pm>
<devices>
<emulator>/usr/libexec/qemu-kvm</emulator>
<disk type='file' device='disk'>
<driver name='qemu' type='qcow2'/>
<source file='/kvm_data/test.img'/>
<target dev='vda' bus='virtio'/>
<address type='pci' domain='0x0000' bus='0x00' slot='0x06' function='0x0'/>
</disk>
<disk type='file' device='cdrom'>
<driver name='qemu' type='raw'/>
<target dev='hda' bus='ide'/>
<readonly/>
<address type='drive' controller='0' bus='0' target='0' unit='0'/>
</disk>
<controller type='usb' index='0' model='ich9-ehci1'>
<address type='pci' domain='0x0000' bus='0x00' slot='0x04' function='0x7'/>
</controller>
<controller type='usb' index='0' model='ich9-uhci1'>
<master startport='0'/>
<address type='pci' domain='0x0000' bus='0x00' slot='0x04' function='0x0' multifunction='on'/>
</controller>
<controller type='usb' index='0' model='ich9-uhci2'>
<master startport='2'/>
<address type='pci' domain='0x0000' bus='0x00' slot='0x04' function='0x1'/>
</controller>
<controller type='usb' index='0' model='ich9-uhci3'>
<master startport='4'/>
<address type='pci' domain='0x0000' bus='0x00' slot='0x04' function='0x2'/>
</controller>
<controller type='ide' index='0'>
<address type='pci' domain='0x0000' bus='0x00' slot='0x01' function='0x1'/>
</controller>
<controller type='virtio-serial' index='0'>
<address type='pci' domain='0x0000' bus='0x00' slot='0x05' function='0x0'/>
</controller>
<controller type='pci' index='0' model='pci-root'/>
<interface type='bridge'>
<mac address='52:54:00:50:b0:bc'/>
<source bridge='br0'/>
<model type='virtio'/>
<address type='pci' domain='0x0000' bus='0x00' slot='0x03' function='0x0'/>
</interface>
<serial type='pty'>
<target type='isa-serial' port='0'>
<model name='isa-serial'/>
</target>
</serial>
<console type='pty'>
<target type='serial' port='0'/>
</console>
<channel type='unix'>
<target type='virtio' name='org.qemu.guest_agent.0'/>
<address type='virtio-serial' controller='0' bus='0' port='1'/>
</channel>
<input type='mouse' bus='ps2'/>
<input type='keyboard' bus='ps2'/>
<memballoon model='virtio'>
<address type='pci' domain='0x0000' bus='0x00' slot='0x07' function='0x0'/>
</memballoon>
<rng model='virtio'>
<backend model='random'>/dev/urandom</backend>
<address type='pci' domain='0x0000' bus='0x00' slot='0x08' function='0x0'/>
</rng>
</devices>
</domain>

</domainsnapshot>

⑤、查看所有快照配置文件

[root@kvm ~]# ls /var/lib/libvirt/qemu/snapshot/test

1615484184.xml

⑥、恢复指定快照

[root@kvm ~]# virsh snapshot-revert test 1615482601

⑦、删除快照

[root@kvm ~]# virsh snapshot-delete test 1615482601

Domain snapshot 1615482601 deleted

9、磁盘格式

查看虚拟磁盘格式，命令如下：

[root@kvm ~]# qemu-img info /kvm_data/test.img


image: /kvm_data/test.img
file format: qcow2
virtual size: 10G (10737418240 bytes)
disk size: 1.1G
cluster_size: 65536
Format specific information:
compat: 1.1

lazy refcounts: true

创建2 GB的RAW格式磁盘，命令如下：

[root@kvm ~]# qemu-img create -f raw /kvm_data/test_1.img 2G


Formatting '/kvm_data/test_1.img', fmt=raw size=2147483648
RAW格式的磁盘转换为qcow2格式，命令如下：
[root@kvm ~]# qemu-img convert -O qcow2 /kvm_data/test_1.img

/kvm_data/test_1.qcow2

查看test1.img大小，命令如下：

[root@kvm ~]# ls -lh /kvm_data/test_1.img


-rw-r--r-- 1 root root 2.0G May 3 15:11 /kvm_data/test_1.img
[root@kvm ~]# ls -lh /kvm_data/test_1.qcow2
-rw-r--r-- 1 root root 193K May 3 15:38 /kvm_data/test_1.qcow2
//可以看到qcow2文件比较小，raw文件大小和我们指定空间大小一样是2G

//raw格式的磁盘性能比qcow2要好，但是raw格式的磁盘无法做快照

将test02转成raw格式，命令如下：

[root@kvm ~]# qemu-img convert -O raw

/kvm_data/test02.img /kvm_data/test02_2.raw

更改磁盘格式和文件路径，然后启动test02虚拟机，命令如下：

[root@kvm ~]# virsh edit test02


…………
<disk type='file' device='disk'>
<driver name='qemu' type='qcow'/>
<source file='/kvm_data/test02.img'/>
<target dev='vda' bus='virtio'/>
<address type='pci' domain='0x0000' bus='0x00' slot='0x06' function='0x0'/>
</disk>
//找到上面这部分将qcow修改为raw，/kvm_data/test02.img改为/kvm_data/test02_2.raw
<disk type='file' device='disk'>
<driver name='qemu' type='raw'/>
<source file='/kvm_data/test02_2.raw'/>
<target dev='vda' bus='virtio'/>
<address type='pci' domain='0x0000' bus='0x00' slot='0x06' function='0x0'/>
</disk>

………………

查看磁盘所属用户和组，命令如下：

[root@kvm ~]# ls -l /kvm_data/


total 3310628
drwx------ 2 root root 16384 Apr 29 00:20 lost found
-rw-r--r-- 1 root root 10737418240 May 3 16:14 test02_2.raw
-rw------- 1 root root 1133772800 May 3 16:02 test02.img
-rw-r--r-- 1 root root 2147483648 May 3 15:11 test_1.img
-rw-r--r-- 1 root root 197120 May 3 16:05 test_1.qcow2

-rw------- 1 root root 10739384832 May 3 14:14 test.img

启动虚拟机test02，然后再次查看磁盘所属用户和组，命令如下：

[root@kvm ~]# virsh start test02


Domain test02 started
[root@kvm ~]# ls -l /kvm_data/
total 3310628
drwx------ 2 root root 16384 Apr 29 00:20 lost found
-rw-r--r-- 1 qemu qemu 10737418240 May 3 16:14 test02_2.raw
-rw------- 1 root root 1133772800 May 3 16:02 test02.img
-rw-r--r-- 1 root root 2147483648 May 3 15:11 test_1.img
-rw-r--r-- 1 root root 197120 May 3 16:05 test_1.qcow2
-rw------- 1 root root 10739384832 May 3 14:14 test.img

//启动后所属组变化成qemu的是test02_2.raw，证明这个磁盘正在被使用

10、磁盘扩容

我们知道，在这里磁盘一共有两种格式，一种是RAW格式，一种是qcow2格式，接下来我们分别给这两种磁盘格式进行扩容。

首先扩容RAW格式，命令如下：

[root@kvm ~]# qemu-img resize /kvm_data/test02_2.raw 2G

Image resized.

查看test02_2.raw信息，命令如下：

[root@kvm ~]# qemu-img info /kvm_data/test02_2.raw


image: /kvm_data/test02_2.raw
file format: raw
virtual size: 12G (12884901888 bytes)

disk size: 1.0G

进入虚拟机test02，使用fdisk -l查看磁盘，命令如下：

[root@kvm ~]# virsh console test02


[root@localhost ~]# fdisk -l
Disk /dev/vda: 10.7 GB, 10737418240 bytes, 20971520 sectors
Units = sectors of 1 * 512 = 512 bytes
Sector size (logical/physical): 512 bytes / 512 bytes
I/O size (minimum/optimal): 512 bytes / 512 bytes
Disk label type: dos
Disk identifier: 0x0005b865
Device Boot Start End Blocks Id System
/dev/vda1 * 2048 1026047 512000 83 Linux
/dev/vda2 1026048 20971519 9972736 8e Linux LVM
Disk /dev/mapper/centos-root: 9093 MB, 9093251072 bytes, 17760256 sectors
Units = sectors of 1 * 512 = 512 bytes
Sector size (logical/physical): 512 bytes / 512 bytes
I/O size (minimum/optimal): 512 bytes / 512 bytes
Disk /dev/mapper/centos-swap: 1073 MB, 1073741824 bytes, 2097152 sectors
Units = sectors of 1 * 512 = 512 bytes
Sector size (logical/physical): 512 bytes / 512 bytes
I/O size (minimum/optimal): 512 bytes / 512 bytes

//可以看到磁盘还是10 GB

退出终端，关闭test02虚拟机，重新启动，然后再次进入虚拟机test02，使用fdisk -l查看磁盘，命令如下：

[root@kvm ~]# virsh destroy test02


Domain test02 destroyed
[root@kvm ~]# virsh start test02
Domain test02 started
[root@kvm ~]# virsh console test02
[root@localhost ~]# fdisk -l
Disk /dev/vda: 12.9 GB, 12884901888 bytes, 25165824 sectors
Units = sectors of 1 * 512 = 512 bytes
Sector size (logical/physical): 512 bytes / 512 bytes
I/O size (minimum/optimal): 512 bytes / 512 bytes
Disk label type: dos
Disk identifier: 0x0005b865
Device Boot Start End Blocks Id System
/dev/vda1 * 2048 1026047 512000 83 Linux
/dev/vda2 1026048 20971519 9972736 8e Linux LVM
Disk /dev/mapper/centos-root: 9093 MB, 9093251072 bytes, 17760256 sectors
Units = sectors of 1 * 512 = 512 bytes
Sector size (logical/physical): 512 bytes / 512 bytes
I/O size (minimum/optimal): 512 bytes / 512 bytes
Disk /dev/mapper/centos-swap: 1073 MB, 1073741824 bytes, 2097152 sectors
Units = sectors of 1 * 512 = 512 bytes
Sector size (logical/physical): 512 bytes / 512 bytes

I/O size (minimum/optimal): 512 bytes / 512 bytes

可以看到已经变成12 GB了。

接下来，我们怎么使用新增加的这2 GB磁盘，那就是分区，命令如下：

[root@localhost ~]# fdisk /dev/vda


Welcome to fdisk (util-linux 2.23.2).
Changes will remain in memory only, until you decide to write them.
Be careful before using the write command.
Command (m for help): n
//新建分区
Partition type:
p primary (2 primary, 0 extended, 2 free)
e extended
Select (default p): p
Partition number (3,4, default 3):
//按Enter键
First sector (20971520-25165823, default 20971520):
//按Enter键
Using default value 20971520
Last sector,  sectors or  size{K,M,G} (20971520-25165823, default 25165823):
//按Enter键
Using default value 25165823
Partition 3 of type Linux and of size 2 GiB is set
Command (m for help): p
//查看分区列表
Disk /dev/vda: 12.9 GB, 12884901888 bytes, 25165824 sectors
Units = sectors of 1 * 512 = 512 bytes
Sector size (logical/physical): 512 bytes / 512 bytes
I/O size (minimum/optimal): 512 bytes / 512 bytes
Disk label type: dos
Disk identifier: 0x0005b865
Device Boot Start End Blocks Id System
/dev/vda1 * 2048 1026047 512000 83 Linux
/dev/vda2 1026048 20971519 9972736 8e Linux LVM
/dev/vda3 20971520 25165823 2097152 83 Linux
Command (m for help): w
//保存退出并退出终端
除了对已有磁盘扩容外，还可以额外增加磁盘，命令如下：
[root@kvm ~]# qemu-img create -f raw /kvm_data/test02_3.raw 5G

Formatting '/kvm_data/test02_3.raw', fmt=raw size=5368709120

使用virsh edit编辑test02虚拟机，将新磁盘增加到test02虚拟机，命令如下

[root@kvm ~]# virsh edit test02


………………
<disk type='file' device='disk'>
<driver name='qemu' type='raw'/>
<source file='/kvm_data/test02_2.raw'/>
<target dev='vda' bus='virtio'/>
<address type='pci' domain='0x0000' bus='0x00' slot='0x06'
function='0x0'/>
</disk>
//找到这一部分内容，在下面增加以下内容
<disk type='file' device='disk'>
<driver name='qemu' type='raw'/>
<source file='/kvm_data/test02_3.raw'/>
<target dev='vdb' bus='virtio'/>
<address type='pci' domain='0x0000' bus='0x00' slot='0x09'
function='0x0'/>
</disk>

………………

关闭test02虚拟机，重新启动，然后进入该虚拟机，使用fdisk -l查看磁盘，命令如下：

[root@kvm ~]# virsh destroy test02


Domain test02 destroyed
[root@kvm ~]# virsh start test02
Domain test02 started
[root@kvm ~]# virsh console test02
[root@localhost ~]# fdisk -l
Disk /dev/vda: 12.9 GB, 12884901888 bytes, 25165824 sectors
Units = sectors of 1 * 512 = 512 bytes
Sector size (logical/physical): 512 bytes / 512 bytes
I/O size (minimum/optimal): 512 bytes / 512 bytes
Disk label type: dos
Disk identifier: 0x0005b865
Device Boot Start End Blocks Id System
/dev/vda1 * 2048 1026047 512000 83 Linux
/dev/vda2 1026048 20971519 9972736 8e Linux LVM
/dev/vda3 20971520 25165823 2097152 83 Linux
Disk /dev/vdb: 5368 MB, 5368709120 bytes, 10485760 sectors
Units = sectors of 1 * 512 = 512 bytes
Sector size (logical/physical): 512 bytes / 512 bytes
I/O size (minimum/optimal): 512 bytes / 512 bytes
Disk /dev/mapper/centos-root: 9093 MB, 9093251072 bytes, 17760256 sectors
Units = sectors of 1 * 512 = 512 bytes
Sector size (logical/physical): 512 bytes / 512 bytes
I/O size (minimum/optimal): 512 bytes / 512 bytes
Disk /dev/mapper/centos-swap: 1073 MB, 1073741824 bytes, 2097152 sectors
Units = sectors of 1 * 512 = 512 bytes
Sector size (logical/physical): 512 bytes / 512 bytes

I/O size (minimum/optimal): 512 bytes / 512 bytes

可以看到多了一块5 GB的磁盘，退出终端。

接下来，我们扩容qcow2格式的磁盘，命令如下：

[root@kvm ~]# qemu-img resize /kvm_data/test.img 2G


Image resized.

//若提示qemu-img: Can't resize an image which has snapshots，需要删除快照

查看test.img信息，命令如下：

[root@kvm ~]# qemu-img info /kvm_data/test.img


image: /kvm_data/test.img
file format: qcow2
virtual size: 12G (12884901888 bytes)
disk size: 1.1G
cluster_size: 65536
Format specific information:
compat: 1.1

lazy refcounts: true

关闭test虚拟机，重新启动，然后再次进入虚拟机test02，使用fdisk -l查看磁盘，命令如下：

[root@kvm ~]# virsh destroy test


Domain test destroyed
[root@kvm ~]# virsh start test
Domain test started
[root@kvm ~]# virsh console test
[root@localhost ~]# fdisk -l
Disk /dev/vda: 12.9 GB, 12884901888 bytes, 25165824 sectors
Units = sectors of 1 * 512 = 512 bytes
Sector size (logical/physical): 512 bytes / 512 bytes
I/O size (minimum/optimal): 512 bytes / 512 bytes
Disk label type: dos
Disk identifier: 0x0005b865
Device Boot Start End Blocks Id System
/dev/vda1 * 2048 1026047 512000 83 Linux
/dev/vda2 1026048 20971519 9972736 8e Linux LVM
Disk /dev/mapper/centos-root: 9093 MB, 9093251072 bytes, 17760256 sectors
Units = sectors of 1 * 512 = 512 bytes
Sector size (logical/physical): 512 bytes / 512 bytes
I/O size (minimum/optimal): 512 bytes / 512 bytes
Disk /dev/mapper/centos-swap: 1073 MB, 1073741824 bytes, 2097152 sectors
Units = sectors of 1 * 512 = 512 bytes
Sector size (logical/physical): 512 bytes / 512 bytes

I/O size (minimum/optimal): 512 bytes / 512 bytes

分区新增加的2 GB磁盘，命令如下：

[root@localhost ~]# fdisk /dev/vda


Welcome to fdisk (util-linux 2.23.2).
Changes will remain in memory only, until you decide to write them.
Be careful before using the write command.
Command (m for help): n
Partition type:
p primary (2 primary, 0 extended, 2 free)
e extended
Select (default p): p
Partition number (3,4, default 3):
First sector (20971520-25165823, default 20971520):
Using default value 20971520
Last sector,  sectors or  size{K,M,G} (20971520-25165823, default 25165823):
Using default value 25165823
Partition 3 of type Linux and of size 2 GiB is set
Command (m for help): w

/保存并退出终端

新增一块qcow2格式的磁盘，命令如下：

[root@kvm ~]# qemu-img create -f qcow2 /kvm_data/test_2.img 5G

Formatting '/kvm_data/test_2.img', fmt=qcow2 size=5368709120 encryption=off cluster_size=65536 lazy_refcounts=off

使用virsh edit编辑test虚拟机，将新磁盘增加到test虚拟机，命令如下：

[root@kvm ~]# virsh edit test


………………
<disk type='file' device='disk'>
<driver name='qemu' type='qcow2'/>
<source file='/kvm_data/test.img'/>
<target dev='vda' bus='virtio'/>
<address type='pci' domain='0x0000' bus='0x00' slot='0x06' function='0x0'/>
</disk>
//找到这一部分内容，在下面增加以下内容
<disk type='file' device='disk'>
<driver name='qemu' type='qcow2'/>
<source file='/kvm_data/test_2.img'/>
<target dev='vdb' bus='virtio'/>
<address type='pci' domain='0x0000' bus='0x00' slot='0x08' function='0x0'/>
</disk>

………………

关闭test虚拟机，重新启动，然后进入该虚拟机，使用fdisk -l查看磁盘，命令如下：

[root@kvm ~]# virsh destroy test


Domain test destroyed
[root@kvm ~]# virsh start test
Domain test started
[root@kvm ~]# virsh console test
[root@localhost ~]# fdisk -l
Disk /dev/vda: 12.9 GB, 12884901888 bytes, 25165824 sectors
Units = sectors of 1 * 512 = 512 bytes
Sector size (logical/physical): 512 bytes / 512 bytes
I/O size (minimum/optimal): 512 bytes / 512 bytes
Disk label type: dos
Disk identifier: 0x0005b865
Device Boot Start End Blocks Id System
/dev/vda1 * 2048 1026047 512000 83 Linux
/dev/vda2 1026048 20971519 9972736 8e Linux LVM
/dev/vda3 20971520 25165823 2097152 83 Linux
Disk /dev/vdb: 5368 MB, 5368709120 bytes, 10485760 sectors
Units = sectors of 1 * 512 = 512 bytes
Sector size (logical/physical): 512 bytes / 512 bytes
I/O size (minimum/optimal): 512 bytes / 512 bytes
Disk /dev/mapper/centos-root: 9093 MB, 9093251072 bytes, 17760256 sectors
Units = sectors of 1 * 512 = 512 bytes
Sector size (logical/physical): 512 bytes / 512 bytes
I/O size (minimum/optimal): 512 bytes / 512 bytes
Disk /dev/mapper/centos-swap: 1073 MB, 1073741824 bytes, 2097152 sectors
Units = sectors of 1 * 512 = 512 bytes
Sector size (logical/physical): 512 bytes / 512 bytes

I/O size (minimum/optimal): 512 bytes / 512 bytes

退出终端

11、调整CPU内存、网卡

查看虚拟机配置信息，命令如下：

[root@kvm ~]# virsh dominfo test


Id: 8
Name: test
UUID: 49d7cb9c-20dc-42dd-a260-01532b5132e5
OS Type: hvm
State: running
CPU(s): 1
CPU time: 20.8s
Max memory: 1048576 KiB
Used memory: 524288 KiB
Persistent: yes
Autostart: disable
Managed save: no
Security model: none

Security DOI: 0

编辑虚拟机内存，命令如下：

[root@kvm ~]# virsh edit test


…………
<memory unit='KiB'>1048576</memory>
//最大内存
<currentMemory unit='KiB'>524288</currentMemory>
//可用内存
<vcpu placement='static' current='1'>2</vcpu>
//最大cpu
………………
//将以上内容修改为如下内容
…………
<memory unit='KiB'>1048576</memory>
<currentMemory unit='KiB'>624288</currentMemory>
<vcpu placement='static' current='1'>2</vcpu>

…………

关闭虚拟机，重启动虚拟机，命令如下：

[root@kvm ~]# virsh destroy test


Domain test destroyed
[root@kvm ~]# virsh start test

Domain test started

查看虚拟机配置信息，看是否修改成功，命令如下：

[root@kvm ~]# virsh dominfo test


Id: 10
Name: test
UUID: 49d7cb9c-20dc-42dd-a260-01532b5132e5
OS Type: hvm
State: running
CPU(s): 1
CPU time: 21.4s
Max memory: 1048576 KiB
Used memory: 624288 KiB
Persistent: yes
Autostart: disable
Managed save: no
Security model: none

Security DOI: 0

除了这种修改方式之外，还有一种动态修改，命令如下：

[root@kvm ~]# virsh setmem test 800m


//动态修改内存
[root@kvm ~]# virsh setvcpus test 2

//动态修改cpu，只可以增加不可以减少

查看配置信息，看是否修改成功，命令如下：

[root@kvm ~]# virsh dominfo test


Id: 10
Name: test
UUID: 49d7cb9c-20dc-42dd-a260-01532b5132e5
OS Type: hvm
State: running
CPU(s): 2
CPU time: 22.8s
Max memory: 1048576 KiB
Used memory: 819200 KiB
Persistent: yes
Autostart: disable
Managed save: no
Security model: none
Security DOI: 0
[root@kvm ~]# virsh dumpxml test > /etc/libvirt/qemu/test.xml

//需要把配置写入到配置文件里

查看网卡列表，命令如下：

[root@kvm ~]# virsh domiflist test


Interface Type Source Model MAC
-------------------------------------------------------

vnet1 bridge br0 virtio 52:54:00:93:bf:07

增加一块新的网卡，并设置为NAT网络模式（virbr0类似VMware的VMnet8），这里如果写–source br0，则网络模式为桥接，命令如下：

[root@kvm ~]# virsh attach-interface test --type bridge --source virbr0


Interface attached successfully
[root@kvm ~]# virsh domiflist test
Interface Type Source Model MAC
-------------------------------------------------------
vnet1 bridge br0 virtio 52:54:00:93:bf:07
vnet2 bridge virbr0 rtl8139 52:54:00:29:ed:8b

[root@kvm ~]# virsh dumpxml test > /etc/libvirt/qemu/test.xml

进入test虚拟机，查看网卡信息，命令如下：

[root@kvm ~]# virsh console test


[root@localhost ~]# ifconfig
ens10: flags=4163<UP,BROADCAST,RUNNING,MULTICAST> mtu 1500
inet 192.168.122.8 netmask 255.255.255.0 broadcast 192.168.122.255
inet6 fe80::5054:ff:fe29:ed8b prefixlen 64 scopeid 0x20<link>
ether 52:54:00:29:ed:8b txqueuelen 1000 (Ethernet)
RX packets 5186 bytes 7413267 (7.0 MiB)
RX errors 0 dropped 0 overruns 0 frame 0
TX packets 1480 bytes 84889 (82.8 KiB)
TX errors 0 dropped 0 overruns 0 carrier 0 collisions 0
ens11: flags=4163<UP,BROADCAST,RUNNING,MULTICAST> mtu 1500
inet 192.168.16.129 netmask 255.255.255.0 broadcast 192.168.16.255
inet6 fe80::5054:ff:fe15:abbd prefixlen 64 scopeid 0x20<link>
ether 52:54:00:15:ab:bd txqueuelen 1000 (Ethernet)
RX packets 13 bytes 1328 (1.2 KiB)
RX errors 0 dropped 0 overruns 0 frame 0
TX packets 16 bytes 1668 (1.6 KiB)
TX errors 0 dropped 0 overruns 0 carrier 0 collisions 0
eth0: flags=4163<UP,BROADCAST,RUNNING,MULTICAST> mtu 1500
ether 52:54:00:93:bf:07 txqueuelen 1000 (Ethernet)
RX packets 55 bytes 8520 (8.3 KiB)
RX errors 0 dropped 0 overruns 0 frame 0
TX packets 0 bytes 0 (0.0 B)
TX errors 0 dropped 0 overruns 0 carrier 0 collisions 0
lo: flags=73<UP,LOOPBACK,RUNNING> mtu 65536
inet 127.0.0.1 netmask 255.0.0.0
inet6 ::1 prefixlen 128 scopeid 0x10<host>
loop txqueuelen 0 (Local Loopback)
RX packets 0 bytes 0 (0.0 B)
RX errors 0 dropped 0 overruns 0 frame 0
TX packets 0 bytes 0 (0.0 B)

TX errors 0 dropped 0 overruns 0 carrier 0 collisions 0

12、迁移虚拟机

首先关闭虚拟机，命令如下：

[root@kvm ~]# virsh shutdown test

Domain test is being shutdown

查看虚拟机磁盘所在目录，命令如下：

[root@kvm ~]# virsh domblklist test


Target Source
------------------------------------------------
vda /kvm_data/test.img
vdb /kvm_data/test_2.img
hda -
[root@kvm ~]# virsh dumpxml test > /etc/libvirt/qemu/test03.xml
//如果是远程机器，需要把该配置文件拷贝到远程机器上
[root@kvm ~]# rsync -av /kvm_data/test.img /kvm_data/test03.img
//-bash: rsync: command not found则yum install -y rsync
//如果是迁移到远程，则需要把该磁盘文件拷贝到远程机器上
sending incremental file list
test.img
sent 10,742,006,844 bytes received 35 bytes 60,179,310.25 bytes/sec

total size is 10,739,384,832 speedup is 1.00

因为是迁移到本机，配置文件用的是test子机的配置，不改会有冲突，所以需要修改该文件。如果是远程机器不用修改，命令如下：

[root@kvm ~]# vi /etc/libvirt/qemu/test03.xml


<name>test03</name>
//修改domname:
//修改uuid（随便改一下数字，位数不要变）
<disk type='file' device='disk'>
<driver name='qemu' type='qcow2'/>
<source file='/kvm_data/test03.img'/>
<target dev='vda' bus='virtio'/>
<address type='pci' domain='0x0000' bus='0x00' slot='0x06' function='0x0'/>
</disk>
//修改磁盘路径
定义新虚拟机，命令如下：
[root@kvm ~]# virsh define /etc/libvirt/qemu/test03.xml

Domain test03 defined from /etc/libvirt/qemu/test03.xml

查看虚拟机列表，会发现新迁移的虚拟机test03，命令如下：

[root@kvm ~]# virsh list --all


Id Name State
----------------------------------------------------
6 test02 running
- test shut off

- test03 shut off

遇到的问题：1、处理器开启虚拟化，遇见这个问题

解决方法：

管理员运行cmd

执行：bcdedit /set hypervisorlaunchtype off

重启就可以开启了，但是过一段时间，再重启打开虚拟机还是会遇见这个问题，只能再重启解决。

尝试把VMware升级到16也无法解决这个问题。

2、dhclient eh0获取不到IP地址

[root@localhost ~]# dhclient eth0


[root@localhost ~]# ip a
1: lo: <LOOPBACK,UP,LOWER_UP> mtu 65536 qdisc noqueue state UNKNOWN
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 qlen 1000

link/ether 52:54:00:50:b0:bc brd ff:ff:ff:ff:ff:ff

排查问题发现我习惯关闭VMware本地DHCP服务，所以没有获取到IP地址，开启后就获取到IP地址了。

[root@localhost ~]# dhclient eth0


[root@localhost ~]# ip a
1: lo: <LOOPBACK,UP,LOWER_UP> mtu 65536 qdisc noqueue state UNKNOWN
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 qlen 1000
link/ether 52:54:00:50:b0:bc brd ff:ff:ff:ff:ff:ff
inet 192.168.200.128/24 brd 192.168.200.255 scope global dynamic eth0
valid_lft 1801sec preferred_lft 1801sec
inet6 fe80::5054:ff:fe50:b0bc/64 scope link

valid_lft forever preferred_lft forever

KVM虚拟化的安装和基本管理就讲到这里了，如有疑问欢迎多多评论。

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