Krenel Based Virtual Machine In Centos7

Create Virtual Machines in Linux Using KVM
Virtualization packages are means for users to run various operating systems without
“bare metal” hardware are basically, you can run more than one operating system on a
single computer without dual-booting or similar approaches .Virtualization software
emulates a real machine and “fools” the guestoperating system into thinking it’s running
on a real computer.Besides the more obvious advantages,virtual machines help create a
greener and easier to administer computing environment.Looking at the trends in the IT
industry, virtualization has a seen quite a boom in the last few years, because it fits the
conceptof utility computing and/orsoftware as a service . Virtualization can be useful to
you if you are an enterprise architect, developer, a home userorbasically everything in
between.We will begin with the shortintroduction aboutthe virtualization in general,then
we will specifically treat KVM as they seem to be mostpopularopen source full virtualization
solutions. Here we start aboutthe KVM process in detail.

KVM Features
There are manyuseful features and advantages which you will gain when you use KVM to
deployyour virtual platform. KVM hypervisor supports following features:
1. Over-committing : Which means allocating more virtualized CPUs or memorythan
the available resources on the system.
2. Thin provisioning : Which allows the allocation of flexible storage and optimizes the
available space for every guestvirtual machine.
3. Disk I/O throttling : Provides the ability to set a limit on disk I/O requests sentfrom
virtual machines to the hostmachine.
4. Automatic NUMA balancing :Improves the performance ofapplications running on
NUMA hardware systems.
5. Virtual CPU hot add capability : Provides the ability to increase processing poweras
needed on running virtual machines,without downtime.
Make sure that your system has the hardware virtualization extensions:ForIntel-based
hosts, verify the CPU virtualization extension [vmx] are available using following command.
[root@localhost~]# grep -e ‘vmx’/proc/cpuinfo
ForAMD-based hosts,verify the CPU virtualization extension [svm] are available.
[root@localhost~]# grep -e ‘svm’/proc/cpuinfo

If there is no outputmake sure that virtualization extensions is enabled in BIOS. Verify that
KVM modules are loaded in the kernel“it should be loaded bydefault”.
[root@localhost~]# lsmod | grep kvm
[root@localhost ~]# lsmod | grep kvm
Kvm_intel 147785 0
Kvm 464964 1 kvm_intel
Before starting , you will need the rootaccountor non-rootuser with sudo privileges
configured on your system and also make sure that your system is up-to-date.
[root@localhost~]# yum update
Forthis, Selinux must be in Permissive mode.
[root@localhost~]# setenforce 0
Step 1: KVM Installation and Deployment
1 We will install qemu-kvm and qemu-img packages atfirst. These packages provide the
user-level KVM and disk image manager.
[root@localhost~]# yum installqemu-kvm qemu-img
2 Now, you have the minimum requirementto deployvirtual platform on your host, butwe
also still have useful tools to administrate ourplatform such as:
1. virt-manager provides a GUI tool to administrate your virtual machines.

2. libvirt-client provides a CL tool to administrate your virtual environmentthis tool
called virsh.
3. virt-install provides the command “virt-install” to create your virtual machines from
CLI.
4. libvirt provides the server and hostside libraries for interacting with hypervisors and
hostsystems.
Let’s install these above tools using the following command.
[root@localhost~]# yum installvirt-manager libvert libvert-phython libvert-client
3 For RHEL/CentOS7 users,also still having additional package groups such as:
Virtualization Client, Virtualization Platform and Virtualization Tools to install
[root@localhost~]# yum groupinstall virtualization-client virtualization-platform
virtualization-tools
4 The virtualization daemon which manage allof the platform is “libvirtd”. lets restart it.
[root@localhost~]# systemctl restartlibvirtd
5 After restarting the daemon,then check its status by running following command
[root@localhost~]# systemctl status libvirtd

Step 2: Create VMs using KVM
As we mentioned early, we have some useful tools to manage ourvirtual platform and
creating virtual machines.One ofthis tools called [virt-manager] which we use in the next
section.
6 Although virt-manager is a GUI based tool, we also could launch/startit from terminal as
well as from GUI.
[root@localhost~]# virt-manager

Using GNOME Classic
7 After starting the tool, this window will appear.

8 By default you will find manageris connected directly to localhost, fortunately you could
use the same tool to manage anotherhostremotely. From “File” tab, just select “Add
Connection”and this windowwill appear.
Check “Connect to remote host” option then provide Hostname/IP of the remote server. If
you need establishing connection to the remote hostat every time the managerstarting, just
check “Auto Connect” option.
9 Let’s return to our localhost, before creating newvirtual machine you should decide
where will the files be stored?!in other words,you should create the Volume Disk (Virtual
disk / Disk image ) for your virtual machine.
By Right clicking on localhostand selecting “Details” and then select “Storage” tab.

Krenel Based Virtual Machine In Centos7

10 Next, press “New Volume”button, then enter the name ofyour new virtual disk (Volume
Disk) and enter the size which you want/need in the “Max Capacity” section.
The allocation size is the actual size for your disk which will be allocated immediately from
your physical disk after finishing the steps.
Note: This is an important technology in storage administration field which called “thin
provision”. It used to allocate the used storage size only, NOT all of available size.
Forexample,you created virtual disk with size 60G,but you have used actually only 20G,
using this technologythe allocated size from your physicalhard disk will be 20G not60G.
In anotherwords the allocated physical size will by dynamically allocated depending on the
actual used size.

11 You will note that a label of the newVolume Disk has been appeared in the list.
You should also notice the path of the newdisk image (Volume Disk), by default it will be
under/var/lib/libvirt/images, you can verify it using the following command.
[root@localhost Downloads]# ls –l /var/lib/libvirt/images
12 Now, we’re readyto create our virtual machine.Let’s hit the button “VM” in the main
window, this wizard windowwill be appear.

Select the installation method which you will use to create the virtual machine.Fornowwe
will use Localinstall media,later we will discuss the remaining methods.
13 Now it’s time to specify which Localinstall media to be used,we have two options:
From physical[CDROM/DVD].
From ISO image.

Let’s use ISO image method,so you should provide the path of your ISO image.
14 The storage has return back,we will use the virtual disk which we have created early to
install virtual machine on it. It will be as shown.

15 The final step which ask you aboutthe name ofyour virtual machine and another
advanced options let’s talk aboutit later.
Then click finish and wait seconds,controlconsole will appearfor your GuestOS to
manage it

Conclusion
Now you have learned whatis is KVM, Howto manage yourvirtual platform using GUI
tools, How to deployvirtual machine using it and anotherawesome things.

Krenel Based Virtual Machine In Centos7

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