我的Linux生活日記 28.KVM
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在 Linux 中可以透過建立 KVM「核心基礎虛擬機器 (Kernel-based Virtual Machine；KVM）」 建立不同作業系統環境，無論是 RedHat 、Debian 或是 windows 都可以建立。在學習 Linux 的過程是不錯的學習工具。
啟動 CPU 虛擬化技術
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這部份需要進入 BIOS 開啟，AMD 是 VT , Intel 是 VT-x、VT-d 或 VT-c 。
檢查硬體資源是否支援 虛擬技術
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啟動之後可以下指令檢查
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grep --color --perl-regexp 'vmx|svm' /proc/cpuinfo
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安裝
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安裝指令
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sudo apt -y install qemu-system libvirt-clients libvirt-daemon-system qemu-kvm libvirt-daemon bridge-utils virtinst virt-manager libosinfo-bin osinfo-db-tools
sudo systemctl enable libvirtd
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sudo dnf install @virtualization
sudo systemctl enable --now libvirtd
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sudo usermod -aG kvm $(whoami)
sudo usermod -aG libvirt $(whoami)
sudo usermod -aG input $(whoami)
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最佳化設定
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[root@kvm-004 ~]# tuned-adm list
Available profiles:
- accelerator-performance - Throughput performance based tuning with disabled higher latency STOP states
- aws - Optimize for aws ec2 instances
- balanced - General non-specialized tuned profile
- desktop - Optimize for the desktop use-case
- epyc-eda - Optimize for EDA compute workloads on AMD EPYC CPUs
- hpc-compute - Optimize for HPC compute workloads
- intel-sst - Configure for Intel Speed Select Base Frequency
- latency-performance - Optimize for deterministic performance at the cost of increased power consumption
- network-latency - Optimize for deterministic performance at the cost of increased power consumption, focused on low latency network performance
- network-throughput - Optimize for streaming network throughput, generally only necessary on older CPUs or 40G+ networks
- optimize-serial-console - Optimize for serial console use.
- powersave - Optimize for low power consumption
- throughput-performance - Broadly applicable tuning that provides excellent performance across a variety of common server workloads
- virtual-guest - Optimize for running inside a virtual guest
- virtual-host - Optimize for running KVM guests
Current active profile: throughput-performance
[root@kvm-004 ~]# tuned-adm active
Current active profile: throughput-performance
[root@kvm-004 ~]# tuned-adm profile virtual-host
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使用 vhost_net 模組
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[root@kvm-004 ~]# tuned-adm active
Current active profile: virtual-host
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### 使用 vhost_net 模組
```bash
sudo modprobe vhost_net
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設定網路
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sudo virsh net-start default
sudo virsh net-autostart default
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新增 KVM 權限
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sudo usermod -G libvirt-qemu pollochang
sudo usermod -G libvirt pollochang
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KVM 更新OS清單
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sudo apt install libosinfo-bin osinfo-db-tools
wget -O "/tmp/osinfo-db.tar.xz" https://releases.pagure.org/libosinfo/osinfo-db-20240701.tar.xz
wget -O "/tmp/osinfo-db.tar.xz" https://releases.pagure.org/libosinfo/osinfo-db-20231215.tar.xz
wget -O "/tmp/osinfo-db.tar.xz" https://releases.pagure.org/libosinfo/osinfo-db-20160728.tar.xz
wget -O "/tmp/osinfo-db.tar.xz" https://releases.pagure.org/libosinfo/osinfo-db-20181101.tar.xz
wget -O "/tmp/osinfo-db.tar.xz" https://releases.pagure.org/libosinfo/osinfo-db-20250124.tar.xz
sudo osinfo-db-import --local "/tmp/osinfo-db.tar.xz"
osinfo-query os | grep solaris
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Debian 12 火牆使用Firewalld
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❯ sudo virsh net-start default ─╯
error: Failed to start network default
error: internal error: firewalld is set to use the nftables backend, but the required firewalld 'libvirt' zone is missing. Either set the firewalld backend to 'iptables', or ensure that firewalld has a 'libvirt' zone by upgrading firewalld to a version supporting rule priorities (0.7.0+) and/or rebuilding libvirt with --with-firewalld-zone
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/etc/firewalld/firewalld.conf
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FirewallBackend=nftables >> FirewallBackend=iptables
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建立虛擬機
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建立虛擬硬碟
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建立虛擬機之前必須先建立虛擬硬碟。
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sudo qemu-img create -f qcow2 /home/jameschang/VMS/linux/debian9.qcow2 20G
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建立虛擬機器
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建立完虛擬磁碟就是建立虛擬機啦！指令說明如下。
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virt-install --virt-type kvm --name [虛擬機識別名稱] --ram [記憶體大小mb] --disk [虛擬硬碟掛載目錄],format=[虛擬磁碟格式] --network network=[虛擬網路界面] --graphics vnc,listen=0.0.0.0,password=debian9 --noautoconsole --os-type=linux --os-variant=[作業系統版本] --cdrom=[ISO光碟位置]
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sudo virt-install --virt-type kvm --name debian9 --ram 4096 --disk /home/jameschang/VMS/linux/debian9.qcow2,format=qcow2 --network network=network1 --graphics vnc,listen=0.0.0.0,password=debian9 --noautoconsole --os-type=linux --os-variant=debian9 --cdrom=/data/softwares/linux/debian-9.13.0-amd64-netinst.iso
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啟動KVM
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sudo virsh start debian9
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設定開機時啟動
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如果須樣在主機中依開機後就啟動虛擬機可以這樣處理。
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sudo virsh autostart debian9
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KVM 轉 VMDisk
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有時候在 KVM 設定完虛擬機環境後，可以把虛擬機轉成 vmdk 格式，讓其他類型虛擬管理工具使用，如：oracle virtualbox。
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qemu-img convert -f qcow2 -O vmdk zimbra9-ubuntu18.04 zimbra9-ubuntu18.04.vmdk
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KVM 網路
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指定虛擬機網卡IP，除了可以在虛擬機裡設定，也可以直接在KVM 中直接設定
編輯網路
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查詢 KVM 網卡
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$ sudo virsh net-list
Name State Autostart Persistent
--------------------------------------------
default active yes yes
network active yes yes
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virsh net-edit $NETWORK_NAME
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<dhcp>
<range start='192.168.122.100' end='192.168.122.254'/>
<host mac='52:54:00:ed:3c:bc' name='winxp' ip='192.168.122.2'/>
<host mac='52:54:00:19:1b:70' name='loki' ip='192.168.122.3'/>
<host mac='52:54:00:b8:f1:68' name='gilLab' ip='192.168.122.4'/>
<host mac='' name='vm1' ip=''/>
</dhcp>
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$NETWORK_NAME 是
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sudo virsh net-destroy $NETWORK_NAME &&\
sudo virsh net-start $NETWORK_NAME
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設定 mtu
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如果 KVM 有多張網卡，而虛擬機也會需要多張網卡需要設定 MTU，因為預設是1500 ，不設定有可能造成虛擬機網路無法出去的狀況。
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virsh net-edit $NETWORK_NAME
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<network>
...
<bridge ~/>
<mtu size='9000' />
...
</network>
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維運相關-KVM 虛擬硬碟加大
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# [磁碟路徑] [要擴充的容量]
qemu-img resize /kvm/win10 +20G
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qemu-img info /kvm/win10
image: /kvm/win10
file format: qcow2
virtual size: 40 GiB (42949672960 bytes)
disk size: 39.8 GiB
cluster_size: 65536
Format specific information:
compat: 1.1
compression type: zlib
lazy refcounts: true
refcount bits: 16
corrupt: false
extended l2: false
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維運相關-winXP 無法上網
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我工作上有時候也會測試 windows XP ,又碰到無法上網的問題，主要是驅動問題，設定成 Realtek 即可。
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qemu-kvm -net nic,model=rtl8139 -net user -hda /opt/WinXP2010.img -smb /path/to/shared/dir -m 1024
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參考資料
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解決kvm虛擬機器windows系統間歇性網路中斷的問題
參考資料
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觀察那些 KVM 虛擬機，設定成為開機自動啟動？
How to Add Memory, vCPU, Hard Disk to Linux KVM Virtual Machine
架設 Linux KVM 虛擬化主機 (Set up Linux KVM virtualization host)
Network XML format
