KVM (Kernel-based Virtual Machine) is a full virtualization solution for Linux on x86 hardware containing virtualization extensions Intel VT or AMD-V. How do I install KVM under CentOS or Red Hat Enterprise Linux version 5.5?
The Linux kernel 2.6.20 and above included KVM. RHEL 5.5 (and upcoming RHEL 6) supports KVM out of box and it has also been ported to FreeBSD as a loadable kernel module. However, this tutorial is tested on both CentOS and RHEL 5.5 only running 64 bit Intel Xeon CPU (with Intel VT) and 64 bit kernels with SELinux running in enforcing mode.
Why KVM?
XEN allows several guest operating systems to execute on the same computer hardware and it is also included with RHEL 5.5. But, why use KVM over XEN? KVM is part of the official Linux kernel and fully supported by both Novell and Redhat. Xen boots from GRUB and loads a modified host operating system such as RHEL into the dom0 (host domain). KVM do not have concept of dom0 and domU. It uses /dev/kvm interface to setup the guest operating systems and provides required drivers. See the official wiki for more information.
Required Packages
You must install the following packages:
- kmod-kvm : kvm kernel module(s)
- kvm : Kernel-based Virtual Machine
- kvm-qemu-img : Qemu disk image utility
- kvm-tools : KVM debugging and diagnostics tools
- python-virtinst : Python modules and utilities for installing virtual machines
- virt-manager : Virtual Machine Manager (GUI app, to install and configure VMs)
- virt-viewer: Virtual Machine Viewer (another lightweight app to view VM console and/or install VMs)
- bridge-utils : Utilities for configuring the Linux Ethernet bridge (this is recommended for KVM networking)
KVM Package Group
RHEL comes with KVM software group which includes full virtualization support with KVM. You can list all packages in the group as follows:
# yum groupinfo KVM
Sample outputs:
Loaded plugins: rhnplugin, securitySetting up Group ProcessGroup: KVM Description: Virtualization Support with KVM Mandatory Packages: celt051 etherboot-zroms etherboot-zroms-kvm kmod-kvm kvm kvm-qemu-img qcairo qffmpeg-libs qpixman qspice-libs Default Packages: Virtualization-en-US libvirt virt-manager virt-viewer Optional Packages: celt051-devel etherboot-pxes etherboot-roms etherboot-roms-kvm gpxe-roms-qemu iasl kvm-tools libcmpiutil libvirt-cim qcairo-devel qffmpeg-devel qpixman-devel qspice qspice-libs-devel
A Note About libvirt
libvirt is an open source API and management tool for managing platform virtualization. It is used to manage Linux KVM and Xen virtual machines through graphical interfaces such as Virtual Machine Manager and higher level tools such as oVirt. See the official website for more information.
A Note About QEMU
QEMU is a processor emulator that relies on dynamic binary translation to achieve a reasonable speed while being easy to port on new host CPU architectures. When used as a virtualizer, QEMU achieves near native performances by executing the guest code directly on the host CPU. QEMU supports virtualization when executing under the Xen hypervisor or using the KVM kernel module in Linux. When using KVM, QEMU can virtualize x86, server and embedded PowerPC, and S390 guests. See the official website for more information.
A Note About Virtio Drivers
Virtio is paravirtualized drivers for kvm/Linux. With this you can can run multiple virtual machines running unmodified Linux or Windows VMs. Each virtual machine has private virtualized hardware a network card, disk, graphics adapter, etc. According to Redhat:
Para-virtualized drivers enhance the performance of fully virtualized guests. With the para-virtualized drivers guest I/O latency decreases and throughput increases to near bare-metal levels. It is recommended to use the para-virtualized drivers for fully virtualized guests running I/O heavy tasks and applications.
Host Operating System
Your main operating system such as CentOS or RHEL is known as host operating system. KVM is a Linux kernel module that enables a modified QEMU program to use hardware virtualization. You only need to install KVM under host operating systems.
KVM Domains
It is nothing but a guest operating system running under host operating system. Each kvm domain must have a unique name and ID (assigned by system).
Guest Operating Systems
KVM supports various guest operating systems such as
- MS-Windows 2008 / 2000 / 2003 Server
- MS-Windows 7 / Vista / XP
- FreeBSD
- OpenBSD
- Sun Solaris
- Various Linux distributions.
- NetBSD
- MINIX
- QNX
- MS DOS
- FreeDOS
- Haiku
- Amiga Research OS
Install KVM
Type the following command to install KVM under RHEL or CentOS:
# yum install kvm virt-viewer virt-manager libvirt libvirt-python python-virtinst
OR
# yum groupinstall KVM
Important Configuration And Log Files (Directories) Location
The following files are required to manage and debug KVM problems:
- /etc/libvirt/ - Main configuration directory.
- /etc/libvirt/qemu/ - Virtual machine configuration directory. All xml files regarding VMs are stored here. You can edit them manually or via virt-manager.
- /etc/libvirt/qemu/networks/ - Networking for your KVM including default NAT. NAT is only recommended for small setup or desktops. I strongly suggest you use bridged based networking for performance.
- /etc/libvirt/qemu/networks/default.xml - The default NAT configuration used by NAT device virbr0.
- /var/log/libvirt/ - The default log file directory. All VM specific logs files are stored here.
- /etc/libvirt/libvirtd.conf - Master libvirtd configuration file.
- /etc/libvirt/qemu.conf - Master configuration file for the QEMU driver.
TCP/UDP Ports
By default libvirt does not opens any TCP or UDP ports. However, you can configure the same by editing the /etc/libvirt/libvirtd.conf file. Also, VNC is configured to listen on 127.0.0.1 by default. To make it listen on all public interfaces, edit /etc/libvirt/qemu.conf file.
Our Sample Setup
+-------------> vm#1 ( 10.10.21.71 / 123.1.2.4, CentOS MySQL Server) | +-------------> vm#2 ( 10.10.21.72 / 123.1.2.5, FreeBSD 7 Web Server)LAN --> Switch --> eth0 --> -+ 10.10.21.70 | | ---> br0 -+ +----------------+ +-------------> vm#3 ( 10.10.21.73 / 123.1.2.6, OpenBSD 4.x Firewall ) | | ===> | RHEL Server | -----+ | | | KVM | +-------------> vm#4 ( 10.10.21.74 / 123.1.2.7, Solaris 10 Testing Server ) | ---> br1 -+ +----------------+ |Wan --> ISP Router --> eth1 --> -+ 123.1.2.3 +-------------> vm#5 ( 10.10.21.71 / 123.1.2.8, Windows Server Testing Server ) | +-------------> vm#6 ( 10.10.21.71 / 123.1.2.9, RHEL Mail Server )
(Fig.01: Our sample server setup - you need to scroll to see complete diagram)
Where,
Host Configuration
- OS - RHEL / CentOS v5.5 is our host operating system.
- Host has two interface eth0 and eth1
- LAN - eth0 with private ip
- Internet - eth1 with public IPv4/IPv6 address.
- Disk - 73x4 - 15k SAS disk in RAID 10 hardware mode. All VMs are stored on same server (later I will cover SAN/NFS/NAS configuration with live migration).
- RAM - 16GB ECC
- CPU - Dual core dual Intel Xeon CPU L5320 @ 1.86GHz with VT enabled in BIOS.
Virtual Machine Configuration
- Bridged mode networking (eth0 == br0 and eth1 == br1) with full access to both LAN and Internet.
- Accelerator virtio drivers used for networking (model=virtio)
- Accelerator virtio drivers for disk (if=virtio) and disk will show up as /dev/vd[a-z][1-9] in VM.
- Various virtual machines running different guest operating systems as per requirements.
- CentOS / Redhat: Install KVM Virtualization Software
- CentOS / Redhat: KVM Bridged Network Configuration
- KVM virt-manager: Install CentOS As Guest Operating System
- KVM virt-install: Install FreeBSD / CentOS As Guest Operating System
- KVM: Install CentOS / RHEL Using Kickstart File (Automated Installation)
- Troubleshooting KVM Virtualization Problem With Log Files
- KVM Virsh: Redirect FreeBSD Console To A Serial Port
- KVM: Starting / Stopping Guest Operating Systems With virsh Command
- Linux KVM: Disable virbr0 NAT Interface
- FreeBSD / OpeBSD Running in KVM Does Not Accept FTP Traffic
- KVM: Start a Virtual Machine / Guest At Boot Time
- KVM virt-install: Install OpenBSD As Guest Operating System
- Linux KVM: OpenBSD Guest Hangs At Starting tty Flags
- KVM Virtualization: Start VNC Remote Access For Guest Operating Systems
The heading should read ‘virtualization’.
Not bad summary though.
Thanks for the heads up!
Excellent guide. thanks for sharing :)
Which gives better results with non-virtual aware operating system, xen or kvm. I can never remember. I am considering trying to run Windows 7 within a xen or kvm instance on Centos 5.5. Does anyone know if it supports Directx? A couple of the games I play use it for 3d and effects rendering.
Hey Vivek!
This article is as good as others you have posted earlier.Keep up the good work man.Looking forward to the next installment of this article.
Cheers mate!
Hi
as far as I’m aware Novell does not yet support KVM, it is included in SLES11 sp1 as a “technology preview”, I think they call it, ie they include it for you to test but it is not supported, at least not officially.
Cheers
It was tech preview in sles11, fully supported in sles11sp1
I found error in one command yum groupinstall KMV, correct is yum groupinstall KVM
Thanks! The post has been updated.
You can list all packages in the group as follows: #yum groupinfo Virtualization
Hi,
I m getting this error while installing yum groupinstall KVM..
yum groupinstall KVM
Loaded plugins: fastestmirror
Loading mirror speeds from cached hostfile
* addons: mirrors.hns.net.in
* base: mirrors.hns.net.in
* extras: mirrors.hns.net.in
* updates: mirrors.hns.net.in
Setting up Install Process
Resolving Dependencies
–> Running transaction check
—> Package kvm.i386 0:36-1 set to be updated
—> Package virt-manager.i386 0:0.6.1-12.el5 set to be updated
–> Processing Dependency: python-virtinst >= 0.400.3 for package: virt-manager
—> Package virt-viewer.i386 0:0.0.2-3.el5 set to be updated
–> Running transaction check
—> Package python-virtinst.noarch 0:0.400.3-9.el5_5.1 set to be updated
–> Processing Conflict: libvirt conflicts kvm Finished Dependency Resolution
libvirt-0.6.3-33.el5_5.3.i386 from installed has depsolving problems
–> libvirt conflicts with kvm
Error: libvirt conflicts with kvm
You could try using –skip-broken to work around the problem
You could try running: package-cleanup –problems
package-cleanup –dupes
rpm -Va –nofiles –nodigest
The program package-cleanup is found in the yum-utils package.
Hi,
great summary. On fedora core 14 the “yum install ” command not install the qemu-kvm.x86_64 which is installed if I use the command “yum install virtualization”
How about if I want the vcpu more than 16 cores
hello,
Is kvm available on RHEL 5.5 32 bits ?
I have only a 32 bit processor…
Running a 64 bit kernel (RHEL 64 bit) on the host operating system is recommended but not required. You can use 32bit but limited to 2GB ram per VM. A 32 bit server can only host 32-bit guest operating system.
ok thanks for this information, but its not really my request.
I have a RHEL 5.5 32bits distribution (i have only a proc 32bits, i dont have the choice) in a plateform test and i need to install KVM.
Is KVM compatible with a 32 bit distribution? Because i dont find the packet “kvm”, “libvirt”, “virt manager”
RHEL 5.5+ x86 removed 32bit kvm packages. Your options are as follows
a) Go with 64bit (x64) RHEL system as Redhat not planned create 32bit KVM as most VM server runs on 64 bit platform.
b) Go with 32 bit RHEL and compile new kernel with KVM
c) Use Ubuntu or other 32 bit Linux distro that support 32bit KVM
is it possible to create virtual data center in centos, currently this kind of technology is provided by the redhat.
Hi all
could anyone advise me to solve the problem
the problem is as following:
I’ve installed kvm with all its packages and when i want to install win 7 it will be stacked and does not go forward please help
i’ll be appreciated
Please note that RedHat/CentOS was configured to run KVM only on 64-bit operating systems.
For the host Centos OS, what is the recommended installation configurations? (Server or Minimal)? I have chosen Minimal but couldn’t load any GUI for my centos…and is stuck at the step where it is suppose to load a GUI for virtual manager
I want to change the default location of virtual harddisk to another LVM volume.
How can I do this………?
same thing from my side also….For the host Centos OS, what is the recommended installation configurations? (Server or Minimal)? I have chosen Minimal but couldn’t load any GUI for my centos…and is stuck at the step where it is suppose to load a GUI for virtual manager.
Thanks, its very helpful for me :)
Do we have any equivalent application like VMware Virtual Center to manage KVM hosts?
I heard about OVIRT but it has some limitation.
Thanks
first thank you Vivek, for writing an article that brand new newbies could follow, nice organized. Further request to dumb it down by some server sizing how many CPUs, RAM etc especially for small cluster of 1-10 desktops (that is what we like to do)… also do you have articles on how to installed RHEL 64 on a brand new machine?
Sorry folks, I have to start somewhere, I am staring at my RHEL 6.2 ISO images, new server no OS on it, 3.0 GHz CPU quad core and 16 GB RAM. Plugged in and I have no CLUE. I absolutely cannot stand the other techies speak nor understand it.
Everything else I read, just went into total geekdom high brow type writeup/
Vivek any dummy level article that goes step by step or any material I could read up on will be deeply appreciated!!!
Just saw your TOC some install stuff there, will try that… thanks!