Cloud and Other Technologies

Libvirt -  Libvirt is a hypervisor-independent virtualization API that is able to interact with the virtualization capabilities of a range of operating systems. In the past, I wrote a blog on what is Hypervisor, you can study it from there. Here, I give a brief explanation about Hypervisor Hypervisor A layer of software allowing virtualization of a node in a set of virtual machines, this may have different configurations to the node itself. Libvirt is designed to work across multiple virtualization environments, which means that more common capabilities may not be provided. Libvirt provides all APIs required to provision, create, modify, monitor, control, migrate and stop the domains, within the limits of hypervisor support for these operations. Libvirt Supports:- The KVM/QEMU Linux Hypervisor. The Xen hypervisor on Linux and Solaris hosts. The LXC Linux container system. The OpenVZ Linux container system. The User Mode Linux paravirtualized kernel. The V...

Steps-->> Video Help You have to install and download VMware Workstation. Then after installing it follow these steps.... Click on the Create New Virtual Machine. Choose Custom Option, and Click on Next. In the Next step you have to see whether your system meets the minimum requirements or not, if it does, then click on Next. Next Step is to choose the Option for the OS you want to install whether through an ISO image or with the help of CD/DVD. After choosing this you have to give a username and password for the OS you are installing it is mainly the admin password. After that you have to choose the folder to where the OS you want to put in. After that you have to assign the RAM to the OS, and after that you should assign the network type if you want to connect to the web on that OS. After that you have to assign the space to the OS, how much you want to give. At last you just have to Power on the Virtual Machine you have created, and its all done.

Some facts about RPM (RedHat Package Manager) RPM is free and released under GPL (General Public License). RPM keeps the information of all the installed packages under /var/lib/rpm database. RPM is the only way to install packages under Linux systems,if you've installed packages using source code, then rpm won't manage it. RPM deals with .rpm files, which contains the actual information about the packages such as:- what it is, from where it comes, dependencies information, version information etc. There are five basic modes for RPM command Install - It is used to install any RPM package. Remove - It is used to erase, remove or uninstall any RPM package. Upgrade - It is used to update the existing RPM package. Verify - It is used to query about different RPM packages. Query - It is used for the verification of any RPM package. How to check an RPM Signature Package Always check the PGP signature of packages before installing them on your Linx systems ...

How YUM works? Yum is default package used in Linux based operating system. By default it uses SQLite database to retrieve information of available dependency of packages. Yum use Createrpo Package to create repository of the available packages to remove dependency and createrepo create table of packages dependency in the SQLite database. So when yum create a query to install a package First yum search the configuration file listed in path (/etc/yum.repos.d) what repositories are available in the system. Yum update the all repositories available in the configuration file to search the package available. When yum find the package, it resolve the dependency listed in the SQLite database. Yum used list of command to install, update, delete and upgrade to resolve dependencies. check-update - Check for available package updates distribution-synchronization - Synchronize installed packages to the latest available versions. version - Display a version for the ...

YUM- Yellow Dog Update Modifier (YUM) is a Package Manager which is used to resolve Package Dependency. It is developed by Duke University to make improvements in RPM's installation. It is also called open-source command line as well as graphical based package management tool for RPM (Redhat Package Manager). It allows users and System Administrator to easily install, update, remove and search a software package from the repository. Features:- Support for multiple repositories. Simple configuration. Automatic dependency calculation. Fast operation. RPM-consistent behavior. Package group support, including multiple-repository groups. Simple interface. In my next post, i will tell you about how YUM works?

What are Kernel Headers? When installing certain Linux software, you might have come across the term "Kernel Headers" and wondered why the software you were installing required it. Surely, you already have your kernel installed on your dedicated server, so what are they talking about? Kernel Headers refer to the source code of the Linux Kernel. On most binary distributions (RedHat, SUSE, Debian etc.), only the binary form of the kernel is installed by default. This usually takes the form of a package called Linux-image-(Version Number) or something similar. In order to compile software into a kernel module, that software requires the actual source code for the kernel, called kernel headers. Normally, software does not require direct access into the kernel, but for some software, virtualization for example, it needs to create kernel modules. It does this by compiling the modules for your specific kernel version. Therefore, you must have the kernel headers for the c...

Create a bridge between two interfaces Bridge:- A Bridge is a way to connect two different interfaces together. Packets are forward based on Ethernet address, rather that ip address. brctl is used to set up, maintain, and inspect the Ethernet bridge configuration in the Linux kernel. To install bridge in Linux we need following packages bridge-utils tunctl Step-1 yum install bridge-utils tunctl cp /etc/sysconfig/network-scripts/ifcfg-eth0  /etc/sysconfig/network-scripts/ifcfg-br0 Modify the contents of our new file (ifcfg-br0) to resemble the following configuration /etc/sysconfig/network-scripts/ifcfg-br0: DEVICE="br0" NM_CONTROLLED="yes" ONBOOT="yes"   TYPE="Bridge" BOOTPROTO="none" IPADDR="192.168.1.58" PREFIX="24" GATEWAY="192.168.1.1" DNS1="8.8.8.8" DEFROUTE="yes" NAME="Bridge Network br0" Next, we will make a few adjustments to the previou...

Hypervisor Hypervisor or virtual machine manager is a software program that allows multiple operating systems to share a single hardware. Each operating system is independent from each other and having own recourses. There are two types of hypervisor Type1 hypervisor run directly on the hardware also called Bare-Metal Hypervisor. The Guest OS run on the level above hypervisor. Example:- Xen, Citrix, Xenserver, VMware Esxi, Microsoft Hyper-V. Type2 hypervisors run on a host operating system that provides virtualization services and called hosted hypervisor. Example:- VMware Workstation, Virtual Box.

Virsh is a command line interface tool for managing guests and hypervisor. Virsh is a program which uses libvirt to manage KVM Virtual Machines. Virsh Life Cycle to Manage VM's Connect to Hypervisor virsh connect<machine name> $ virsh --connect qemu:///system Create a Virtual Machine from Virsh Create a new instance from virsh console we need an xml file where the template of virtual machines is created. In template we define the requirements of the machine. VM can be created from XML Configuration file. To create a guest with  run the following:- virsh create configuration_file.xml suspending a VM virsh suspend [domain-id, domain-name or domain-uuid] Resuming a VM virsh resume [domain-id, domain-name or domain-uuid] Restoring a VM virsh restore [filename] Saving a VM virsh save [domain-id, domain-name or domain-uuid] Rebooting a VM virsh reboot [domain-id, domain-name or domain-uuid] command