When we talk about VMWARE ESX servers and the virtual environment (virtualization), we actually need to start from understanding what are the virtual machines all about. Virtual machine or virtual computer, means that it is a computer & operating system as we know it, only it is based on software (not hardware). Which means all of its characteristics are based on software definition hosted on a physical machine.

To simplify this explanation without going too deep into the technical measures, it is a definition of what a computer needs to be (emulating it’s exact environment) only those definitions are based on a program that is a configuration of that environment in order to emulate a real computer, but there are no physical parts, they are sort of a logical part.

The resources which are configured for the creation of that virtual machine are being taken from a physical machine, which allocate those resources from the physical machine to the virtual computer. Now since we are allocating part of the real physical sources, we can use the remaining resources to create another instance (another virtual computer), which can use other free resources. So, if we have much resources on a physical computer, like for example a physical 4GB RAM, which we then allocate 1GB of RAM for each virtual machine, we actually get 4 different virtual computers with 1GB RAM, that  can be installed with different operating systems, like Linux, different versions of Windows operating systems, either desktop or servers.

Now if you understand that concept, you now realize that you can test any type of computer or operating system, by raising it virtually, test it, and delete it, without destroying or re-installing your own computer. You just host those virtual machines on the same computer you are working on. Many use those type of ESX servers, to create different types of computer machines to enable testing environment, without purchasing another hardware. For the same price of having a strong server computer, you can get many different servers or desktop, hosted on the same machine, which only share’s it’s resources with those virtual servers, and saves the cost of purchasing a separate computer for each computer we need to use.

What is an ESX Virtual Server? Well, it is the environment that enables to place upon it and manage many different virtual machines (desktop, server computers, with different types of operating systems). ESX Server is one of the mostly used virtual server, even thought the Microsoft Hyper-V virtual server is starting grasp a hold in this market, ESX servers are still the mostly used ones.

The options you can use are:

1. You can dedicate a strong physical server, and install the ESX server operating system on it, which comes as a full environment, which you manage using an external management client (which you can install on your desktop computer) and only certain definitions can be defined using the ESX server management console.
2. You can decide you want to use the ESX Desktop server version, which enables you to host virtual machines, on your desktop computer (no server hardware is required). Now since it is not a server, the amount of virtual computers you can operating online at the same time, will rely on the amount of resources your desktop computer has. You can create many virtual machines, if you have the hard-disk capacity for it, but you will be able to get only one of them online, in case you do not have enough memory, for example.

Advantages of Virtual machines on ESX Servers:

1. You can host many different types of computers on one computer (Cost effective, as you don’t have to spend more money on another hardware computer)
2. You can backup a whole computer (a whole virtual instance) and recover it completely very quickly. (This is a better, quicker solution for backing your whole hardware computer’s operating system, and recover from it, like when you use Norton Ghost).
3. Installation of new servers (virtual servers) are much faster than installing them on a regular physical computer.4.

Disadvantages of Virtual machines on ESX Servers:

1. You need a stronger computer/server to use the ESX server on, in order to utilize many hosted virtual computers at once.
2. If an ESX server crashes, and you have multiple virtual computers/server running on it, they will all go down at once.

Downloading ESX server and start working:

• Follow the instructions on this link – Download ESX Server 3.5
• Installing ESX server – step by step.
• Virtualization Simplified – Guide to Server Virtualization
• Virtual Machine backup guide
• How to install VMware ESX 3.5 inside VMware Workstation 6.5 - Video lesson
• Live IT. Love IT. VMware IT – Comic Video presentation of VMWARE

Summarizing: There are many benefits to using virtual servers, to be able to have the flexibility and ease of installing new servers, and raising a server environment quickly and more securely. But do not forget that it is risky to place all of your eggs in one basket, so for really important servers that server your network you might want to create a more solid infrastructure are at least a contingency solution in case of a disaster.