Virtualisation

Overview

Normally we have a one to one relationship between a server operating system and the server hardware it runs upon. That hardware will run only that single instance of that operating system and the operating system is bound to that manufacturers specific hardware components (through the drivers it runs).

More Complexity

As the software running on our servers gets ever more complex, there is a constant desire to have one server = one application. This makes management easier and reduces the issue of applications clashing when they are hosted on the same server. We are even starting to see this level of complexity with some workstation class applications. The downside of this is we typically end up with server hardware that is capable of running many applications only running a handful or even just one. The reality is that many servers are for the most part often sitting close to idle.

More Hardware

At the same time as this sprawl of hardware is increasing, there are constant pressures to purchase less hardware, which means less equipment to manage, power, cool and replace.

The Solution

Clearly the two scenarios are at complete odds with each other. Fortunately there is a solution - virtualisation. Better still, this is a technology that has been around for a number of years and is now starting to make headway into the small/medium business environments.

Instead of loading the operating system directly onto the hardware, a different operating system is loaded - the Virtual Machine (VM) Hypervisor. The hypervisor provides a mapping layer between the hardware manufacturer's components and a standard set of hardware components that it emulates (in software). The server operating system is then loaded on top of this hypervisor. However, the key element of this hypervisor is that it is able to provide this emulated hardware not only to one installation of the operating system, but to many. These instances of the operating systems are called Virtual Machines or VM's.

This immediately brings us two significant benefits.

Better Resource Utilisation

Now we able to what would have required multiple physical server machines onto perhaps just a single server. Each of these machines operates in isolation, is completely unaware that it is sharing a physical machine with other servers and from the network, is completely indistinguishable from a "normal" server. Each of these operating systems is contained in one single large file, meaning they can be moved from one physical host server to another with relative ease.

Of course, some extra care is now required to ensure these VM's do not consume all the available resources (CPU, Memory, Disk) on the physical servers.

Business Continuity

The virtual machines are hardware agnostic. The hardware they see (disk controllers, network cards etc) is the hardware provided by the hypervisor and that is the same hardware no matter what make/model of physical computer they are running on. With these VM's being contained in simple files, we can quite literally copy a VM running on a Dell server to an HP server to an IBM server and they will run with no reconfiguration or driver changes.

Rapid Server Recovery

Suddenly we have a whole new level of business continuity at our disposal. At the most basic level, we can backup these VM's and in the event of a loss of hardware, they can be copied onto replacement hardware and restarted. No reinstallation of the operating system or lengthy and complex recovery from backup. Moving hardware generations with the same OEM can be as complex as changing OEM. With virtualisation, this is no longer an issue.

Server Virtualisation

Server Virtualisation in the SME/SBE environment has some different drivers compared to the enterprise organisations where it originated.

The key driver for Server Virtualisation in the enterprise class of company was to reduce the number of physical servers. This in turn reduces the space, power, cooling and maintenance costs. If you are an organisation with 30,000 servers and you can reduce this to 5,000 servers the savings are significant.

In the SME/SMB environment, while there are cost savings moving from say three servers to one, they are not so significant. There is also the issue of now having all the servers on a single physical machine. Loss of one physical server really means the loss of three servers.

However, even for an organisation with just a single server, making that server into a VM and running the free version of VMware (ESX/i) gives us the benefit of the business continuity described above. We would now need to have a compelling reason not to use a hypervisor even for a single server deployment.

Desktop Virtualisation

Desktop virtualisation is built upon the same requirements as server virtualisation and upon the same solutions.

Rather than supply traditional desktops, these can be replaced with thin-terminals and the users remote desktop to their actual computer. These computers are then VM's running on the servers. Thin-terminals typically have no moving parts and are very low powered, low cost appliances. They are particularly suited to the factory/production environment.

Again, the enterprise class companies have their reasons for this sort of solution, but there can be benefits available to the SME/SMB organisations as well. This is particularly useful for making legacy applications available without having to keep legacy hardware running. It can also be beneficial where remote users need to access an application in the office and solutions such as Citrix are prohibitively expensive and overkill.

Data Virtualisation

It is now possible to run a Storage Area Network (SAN) in a virtual environment, so the storage itself becomes virtualised. This can help reduce the costs of implementing a SAN environment for VMware.

Exmos have recently implemented several instances of HP LeftHand SAN/IQ VSA which is a SAN that runs in virtual environment. For these installs the SAN/iQ VSA was hosted on VMware’s ESX/i (free) virtual platform.

Firewall Virtualisation

In order to provide security between VM's it is now possible to run a virtualised Stonegate firewall in the VM environment.