VMWare Virtual Infrastructure - a primer

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I've had a couple of people PM me in the past week or so asking for advice about what ESX is, how it works and its benefits. There are plenty of articles around on the web explaining the benefits of virtualisation, but precious few seemed to be aimed at explaining what VI3 is to the virtualisation novice. instead of just composing replies in PMs, I thought it might be a nice idea to post a 'beginner's guide' to VMWare's premier virtualisation technology in the hope that anyone else who wants to know in the future might find it useful.

I'm going to have to do this in parts, because I've got a bust couple of weeks ahead at work!

What is Virtual Infrastructure 3?

First up, an explanation of what VI3 is. You will probably hear most people, when they talk about VMWare's enterprise technology, refer to it as 'ESX'. Whilst it's true that ESX is the underlying operating system that makes bare-metal (or 'true') virtualisation work, ESX is only part of the picture. In order to fully realise the benefits of enterprise-virtualisation, some more elements are required. these include:

Shared Storage:
Required to get all the benefits of being able to 'move' virtual machines from one ESX server (or 'host') to another

Storage Network - either fibre channel or iSCSI:
So that shared storage can be realised, a storage network is required. Fibre Channel is more expensive but generally offers better performance than iSCSI (though this has become less true in recent years)

VirtualCenter - VMWare's infrastructure management product:
The 'brains' of a virtual infrastructure, absolutely required to enable proper management of your virtual environment

ESX Server:
The 'guts' of a virtual infrastructure - ESX server actually runs the virtual machines in your environment. When used in conjunction with VirtualCenter, multiple ESX hosts 'clustered' (pooled together) provide failover, resource management and high availability, allowing for high uptime, maintenance of individual ESX hosts without losing any VMs (provided capacity is planned properly) and lowering of TCO by allowing you to make full use of your resources, rather than having servers sitting idle 90% of the time.

All the above combined together comprise VMWare's 'Virtual Infrastructre' product, and anyone truly running ESX in the way it was intened and provides most benefit, will in fact by using Virtual Infrastructure rather than 'just' ESX.

What benefits does running virtual provide?

Much is made, seemingly on a regular basis, about some new technology that has the potential to revolutionise the way IT infrastructure is provided. However, running virtual really does have this potential. The benefits of doing so include:

Hardware Replacement:
It is possible to eliminate 90% of physical servers in most environments and replace them with Virtual Machines running on a tenth of the hardware. This alone is enough to cut down the ongoing cost of ownership of most companies - there's no such thing as having to upgrade servers again every three years as part of a refresh cycle. There is an initial cost involved in providing the servers to run ESX and VirtualCenter, but this is offset very quickly by not having to shell out for a new server when the original one runs out of warranty, starts creaking, or fails altogether.

Environmental Factors:
Many companies use a data centre, or are somehow limited in space in their server rooms. Rackspace and power costs are expensive and space is often at a premium in a corporate environment. This makes the benefit of being able to do away with 90% of a company's servers immediately obvious - less space and power consumed equals less money spent on what is effectively 'dead' cost for a company.

High Availability:
With the ability to 'move' virtual machines around, underlying hardware maintenance on each ESX host vastly reduces and, in most cases, eliminates downtime associated with hardware maintenance that would have previously had to be done on the physical machine itself.

Efficient Resource Usage:
Most servers sit idle for 90% of the time. The 4Gb of RAM you chucked in there a couple of years ago was a complete waste - most of the time the server ticks along using nothing more than a quarter of that. Wouldn't it be nice to be able to just allocate a base amount of RAM to start with, then dynamically increase this as needed? With VI's DRS (Distributed Resource Scheduler) this becomes a reality. Where before ten servers might have had 60Gb of RAM between them, and actually used less than a quarter of this most of the time, now you can provision 12Gb to them and allow them to use RAM pooled for other servers that aren't busy at the time. This is one of the coolect things about running virtual

Time Efficiency:
By using VM templates, it is now possible to provision a new server in minutes, rather than days. Remember how unboxing, racking, firing up, installing the OS/imaging, service packing etc etc used to take you the best part of a day? I now provision a new standard build in 30 minutes using VI. Nothing has ever made such a difference to the way I work as VI3!

There are literally hundreds of other benefits, too numerous to go into here, but those are the most important ones. In the next article I'll try and explain how all the elements of VI3 'fit' together.

 

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Excellent, thank you mate

 

Thanks Zeb!

 

Fantastic. Can't wait for the next installment.

Thanks Zeb.

 

really nice post - thanks for taking the time to pull it together.

 

Great Zeb, a good informational read and something I was interested in since Virtualization seems to be hot in IT

 

Thanks zeb. Some very useful information there.

 

Thanks for sharing Zeb, lovely piece of article and information on ESX Server

 

I've pinned this to the forum mate for all to see

Thanks for taking the time to put it together, I'm glad there is someone as into virtualization as me on the boards it was kinda lonely for a while!