Well it’s going to be big (and is already being hyped as such). It’ll be a paradigm shift in the world of IT as we know it. But as I explained in an earlier post: we still have a long way to go before it’ll be mainstream. Cloud Computing is the come together of multiple technologies that already exist. It can be compared to a chemical reaction : Every component is there, we are now in the process to evolve to a new level in IT.

Defining Cloud Computing seems to be something that nobody can agree upon. Here goes mine:

Cloud Computing is an IT model which allows business to scale IT capabilities in such a way that it suits the needs at any time. This can be realized real-time through on-demand self-service. It will be delivered as-a-service anytime, anywhere and will be paid per use afterwards. 

Such a definition can be broken down into 4 characteristics that build up Cloud Computing:

• Elastic & dynamic infrastructure; The infrastructure on which Cloud Computing is build should be able to handle the ever changing demand from business. In such in needs to be elastic and dynamic to supply this demand. Virtualization is the method to provide this flexibility.
• On-demand self service; Business needs to have the ability to self service their needs real-time. Controls should be provided that service this need without the help of external parties.
• Location independent; End-users should be able to access the service anytime, anywhere. Internet is the highway that will connect the service to standard input devices.
• Pay per use; A consumption model must be in place where one pays for the services that have been provided to them. No more, no less. Just the capacity that has be used should be billed afterwards. 

For more information look at the following information sources :

NIST Working Definition Of Cloud Computing

Maria Spinola - An Essential Guide to Possibilities and Risks of Cloud Computing (whitepaper)

Burton Group - Cloud Computing: Transforming IT (whitepaper / needs free registration)

Cisco asked a couple of people to give the definition of Cloud Computing. Look what they came up with.

Click here to view the embedded video.

This movie proves two things to me :

1. Defining Cloud Computing is still difficult for most IT people. 
2. Cloud Computing & Squirrels are in some way connected to one another... Question is : HOW?

ESXi is the small footprint hypervisor created by VMware. It can be implemented on bare-metal servers and is used to host virtual machines. It can be managed by vCenter and is supported by all other VMware product.

So as far as the above few lines state, it is the same as VMware's "thick" hypervisor : ESX. And there are even some advantages which the "thin" ESXi has over ESX, being :

• It's "thin"; As I already stated above, ESXi is a small footprint installation. 32 Mb(!!!) agains approx. 2~3 Gb.
• Quick install; Boot,accept license, choose disk, install, run. A simple installation method to install it on your server. You can even use a USB drive to boot from.
• Easy update; Updating ESXi can be compared to flashing a BIOS. Because it's such a small footprint, just download the newest version and replace the current one. Fast and easy.
• Simple configuration menu; ESXi comes with a simple configuration menu (again BIOS like) which provides you with all the options you can configure in ESXi. No more service console!
• More secure; ESXi having such a small footprint (less patches!) and having no external communication interface (CLI for example) except for VC / RCLI makes it more secure then ESX.

Ok, so why don't we all switch to this small and practicle hypervisor? Well there are some disadvantages which can withhold you from implementing ESXi in a IT production environment, being :

• Service console is gone; For people already working with the fat ESX : No more service console. Which can be a disadvantage if your IT department frequently uses the command line.
• No central unattended distribution method; You can't install ESXi unattended. Which is something you want if you have a large VI. Currently there are no unattended distribution methods as far as I know.
• Can't install local agents; There is no service console anymore. So you can't use local agents on your ESXi host. Everything needs to be able to communicate with the VI API or any other remote connect method to gather information.

Conclusion : ESXi is very suitable for corporate production environment. ESXi has the same functional specs as ESX; you can host virtual machines on it and it can be managed using vCenter. However ESXi has advantages and disadvanstages over ESX. Every environment needs to be evaluated if ESXi is suited for it. If currently you are still dependent on something ESXi can't provide, for example agent in service console, then continue using ESX.

But switching to ESXi is the future! So if you decide not to  switch now, prepare yourself for the future. Start using ESXi in your test environment, gain experience. Communicate current flaws to VMware and your third party tooling / hardware vendors. They can make this product better with your input!

For more information look at following links. There is a lot of information about ESXi. Read it and make your decision.

VMware whitepaper The Architecture of VMware ESXi

VMware whitepaper Managing VMware ESXi

Presentation by Amir Sharif (VMware) Managing ESXi in the datacenter (Need VMworld login account)

David Sumsky : Differences between ESX and ESXi

David Sumsky : Technical differences between ESX and ESXi

KB 1006543 : ESX and ESXi comparison

KB 1003345 : Differences in supported networking features between ESX server 3.5 and ESX server 3i

Update: When using ESXi you can install agents in VMware's VIMA. Which also can be used to run the esxcfg commands (Thanx for the additional info goes to Duncan Epping)

Starting server virtualization is always a difficult task to begin with. First thing you need to deside is which servers you want to virtualize (Well some pointers in that direction : all of them!). But with all difficult tasks you need to take a structured approach. Business isn't  waiting for you to bring down their critical applications. Therefor approach it one step at a time. This gives you the structured approach you need, slowly entering the learning curve of virtualization and giving your IT department the time to adapt to all virtualization technologies.

I would always advice to use a capacity planning tool for your "physical" server environmen, before beginning to start server virtualization. Tools like VMware Capacity Planner and Novell Platespin PowerRecon give you a good insight in what the workloads are on your physical servers. This will then be presented to you in a report with an advice for the most optimal virtual workload distribution across your "yet to be build" virtual infrastructure.

Besides these technical tools, you can also use SCOPE. A conceptual tool by Danielle Ruest and Nelson Ruest. SCOPE lets you quickly identify which workloads to start with. Begin in the lab, maybe even with the lab machines themselves, and slowly move your virtual workloads into production.

SCOPE is the step-by-step approach to virtualize your complete environment. So virtualize your environment in the following steps :

1. Easy workloads; Servers that don't consume a large workload and can be easily virtualized.
2. Production workloads; Server used by users on a day-to-day business but that aren't critical to your line of business
3. Operational workloads; These server are mainly used by the IT department itself. Servers which demand a high workload but aren't business critical
4. Complex workloads; Server that are, already without virtualization, complex to maintain. These includes the servers which have common applications installed on them in mostly enabled with clustering / load balancing.
5. Special workload; Each IT infrastructue has those servers which require special attention. When finishing the virtualization of your complete IT infrastructure, these servers will finish the job.

So as you can see, SCOPE gives you a five step approach to virtualizing your IT infrastructure. This will hopefully help you in creating a good virtualization strategy!

More information you can find here.

Video has been on the net some time now. It was published before VMworld 2008. Still I love to put it here to show you what an amazing feature it is. It's also great because you can see what the VMware product line is capable of.  The video shows you a normal business day with a 4-node VMware cluster being hammered by your average production servers accompanied by some very nice music.

Click here to view the embedded video.

 I'm always looking for material to help other people understand what virtualization is all about. Came across this document by Mitch Tulloch of the Microsoft Virtualization Team. It isa nice PDF document about the different types of infrastructure virtualization solutions (based upon Microsoft technologies ofcourse) and is written in such a style that everybody can understand it. So if your looking for information about virtualization and are new to it, please have a look at this document. Ofcourse it's also usefull for all you virtualizaton geeks as a reference to all the Microsoft Virtualization products.

 Your can find the document here. 

rPath created a video for everybody who is as confused as I was when I first heard the term "cloud computing". It explains cloud computing in plain english (as they state it). But also give you an explanation on how buzz words like virtualization, utility computing and software-as-a-service correlate to cloud computing.

Well get yourself a nice bucket of popcorn and enjoy!

Click here to view the embedded video.