Install and Configure VM ware ESXi 4.1 host

As it was stated in previous post that ESXi 4.1 software has a footprint as small as 70 mb, just like firmware insalled on the system. It comes as embedded in a server's physical hardware by vendor or burnt onto an external USB key. But remember that moving ESXi embedded on USB external key from one server to another is not supported. The ESXi software also comes as an installable CD/DVD.

Let's now proceed with the installation. We are considering Dell server which meets all pre-rquisits, hardware requirements etc. and we are installing from a DVD. To know more about hardware requirements please visit below link: http://kb.vmware.com/kb/1022101

Installation

Turn on the server, insert the DVD and boot from disk. Once installation is initiated, it will take few minutes to complete without any further keyboard inputs and you will be presented with following screen after installation is complete.

Configuration

Next step is to configure your ESXi 4.1 host. Press F2 to go to configuration screen. You will be prompted for user name password. By default admin user is 'root' and password is blank. Once you login you will reach to configuration console know as (DCUI) Direct Console User Interface. The DCUI looks as below:

First thing is to configure root password. It is important to configure root password to be able to login to vSphere client.

-Configure Host Name
-Configure IP Address, Subnet mask, Gateway
-Configure DNS servers.

Once above configuration is done, press F2 to exit the DCUI and F12 to reboot your host. Make sure you add a host record to your DNS server for this ESXi host. Now you are ready to create virtual machines on your ESXi 4.1 host. Open browser on any machine in the same subnet in which you have your host. Type the host name or IP address of your ESXi 4.1 host and you will be presented with below screen:

Click Download vSphere Client, once download completes continue with the istallation. Once installation is complete launch vSphere client from Start > All programmes >> enter the IP address or Host Name of your ESXi 4.1 host >> user name - root and password.

You are now in virtualisation world, explore all settings and my next post will be about creating virtual machines.

What is Virtualisation

The ability to run multiple machines with separate Operating system and Application on a single machine is Virtualisation. In other words the technology with which we can transform hardware into software is Virtualisation. Virtualisation uses either Hosted Architecture or Bare-Metal hypervisor Architecture.

HOST BASED VIRTUALISATION
It requires an Operating System to be installed on a computer. For example a computer which is running Windows 7/xp or any linux Operating system, VMWare server or workstation Virtualisation layer is installed on it. This is called host based Virtualisation. Once VM ware server/workstations version is installed, virtual machines can be created and deployed. This virutal machines will have their own Operating Systems and set of Applications. Though this is good solution in testing environment and production environment to certain extent but this might not be an idle solution for production environment. There are few drawbackups e.g. rebooting hosting OS means all virtual machines will be rebooted too and many more.

VIRTUALISATION USING A BARE-METAL HYPERVISOR
A Bare-metal hypervisor system does not require an operating system. The Hypervisor itself is an Operating System. It installs the virutalisation layer directly on a clean x86-based system. Because a bare-metal hypervisor architecture has direct access to the hardware resources, rather than going through the Operating System which make it more efficient than hosted architecture. This delivers greater scalability, robustness and performance. A hypervisor is the primary component of virtualisation that enables basic computer system partitioning i.e. simple partitioning of CPU, memory and I/O. VMware ESX/ESXi employs a bare-metal hypervisor architecture on certified hardware for datacenter-class performance.

WHAT IS A VIRTUAL MACHINE
From a user's perspective, a virtual machine is a software platform that like a physical computer runs an operating system and applications.
From Hypervisor's perspective, a virtual machine is a discrete set of files. The main files are as below;

- Configuration file
-Virtual disk file
- NVRAM settings file
-Log file

WHY VIRTUALISATION
Virtual machines have many advantages over physical machines.
Virtual machines are easy to move and copy across different hosts.

Encapsulated into files.

Independent of Physical hardware.

Isolated from othr virtual machines.

Insulated from hardware changes.

Provides the ability to support legacy applications.

Allows server to be consolidated.