As the CIO of a solutions provider in the Netherlands, Erik Westhovens spends a great deal of his time figuring out ways his clients can do more with less. Many of the solutions he recommends involve the use of virtualization in one form or another. Here's his unbiased assessment of the current state of virtualization technologies.

What is Virtualization?

Virtualization. The big word in system management and ICT land. But what is virtualization?

There are several ways of virtualization in the IT business, read on to learn more about each.

Quote from Wikipedia: "In computing, virtualization is a broad term that refers to the abstraction of computer resources." Another useful definition is "a technique for hiding the physical characteristics of computing resources from the way in which other systems, applications, or end users interact with those resources. This includes making a single physical resource (such as a server, an operating system, an application, or storage device) appear to function as multiple logical resources; or it can include making multiple physical resources (such as storage devices or servers) appear as a single logical resource."

First, let's categorize the different types of virtualization:

1. Hardware Virtualization
2. Presentation Virtualization
3. Connectivity Virtualization
4. Application Virtualization

Hardware Virtualization

There are several virtualization products on the market. The first one I ever met was the Unix emulator. There was a very big box somewhere in the dungeons of a company, and all the clients were connecting to it with an emulator that created a kind of GUI to reach the dungeon's data. The GUI actually was a black box where you could send in a Unix command to extract that particular piece of info you needed.

VMware

Running complete virtual OS systems inside one piece of hardware. Very useful for developers, but is also brought back the amount of hardware in your dungeon.

Hardware equals power usage equals heat development.

The more boxes you have in your dungeon the bigger the heat development will be, and the bigger your airco's need to be to cool down the dungeon.

Microsoft came with VirtualPC

The same as VMware, much cheaper, but it had one disadvantage. Virtual PCs are very slow. This is where virtualisation got its first "black" eye. It is no virtualization, but emulation. The virtual PC is fully isolated. Where VMware manages to share a hard disk with the guest operating system, as if it would be local hardware, Microsoft can only interact through the network interface.

Presentation Virtualization

Citrix Winframe came to market for Windows NT 3.51. It virtualized an application and the user could use it on every PC. The application actually runs on the big server down in the dungeons of the company together with lots of other applications.

Then Citrix came with Metaframe

Metaframe was able to provide a user with a virtual desktop that actually runs on that big enterprise server somewhere in the same dungeon that the Unix machine was running. This gave the big benefit of centralized management.

The purpose of Citrix was to share resources from a big box and use them for the client.

With Metaframe 3.X they also provided the resources to combine the server and local resources on the same desktop. Instantly and fully transparent.

2X

In 2007 a new product comes to the market named 2X. 2X is a easy way to virtualize software like Citrix does, but it is easier to set up and maintain.

DAV

In 2008 a new player comes to that market to provide application sharing without a Terminal server and or Citrix. You simply need a Windows XP machine, SVS, DAV (codename of the product) and an Internet connection.

Users get access to a website where they have to logon, and they have full access to all the applications that they share.

Fast and easy.

Connectivity Virtualization

This is the most unknown way of Virtualization, and lot of us guys are using it. So what is it?

I use one example. VPN client. The VPN client builds a tunnel to the network that you wish to connect to, and keeps the tunnel shut from others who try to get in.

But you are actually not building a tunnel. You send packages with a strong encryption to another computer that can verify the package and then use it. The whole connection will follow some hops (routers on the Internet) without changing the path.

If a router fails, the connection drops, and a new VPN is built. You will not notice this. Without a VPN, a package that also can be encrypted always searches the shortest way to the receiving party.

As an example, take this article. I'm writing it in the Netherlands, and as soon as I press submit, the article is divided in small pieces and sent to the server where the Juice is located. Most packages will follow the AMX in Amsterdam and then go to New York, and then will find their way to the server. But if the AMX is very busy, some of these will follow another route, and that most likely will be Paris, then Chicago and then the correct location. If I use a VPN, all packages will follow the exact same route.

Software Virtualization

Softgrid

In 2001 there was a new revolutionary technique to sequence software, and to deliver it to the local PC. Softgrid was born.

In contradiction to Citrix and Unix, Softgrid delivers software to the local machine so it could also be used off line.

In 2005 Softgrid was sold to Microsoft.

But is Softgrid virtualization? In my opinion NOT. Softgrid hides the application from the OS, and it is difficult to get the layers to work together. Setting this up can be done, but it takes a lot of time and knowledge.

Thinstall

The second party that brought software Virtualization is Thinstall.

With Thinstall you package the software in a single executable. Very easy to distribute, but also some disadvantages. The other virtualization tools can be built to repair fast and easy. In Thinstall it means that you have to replace the single executable. Also the transparency between the layers is not manageable. You can use cut and paste, but you are not able to use DLLs from package one together with package two.

Software Virtualization Solution

In 2006 Altiris came with SVS. Software virtualization as it should be. All virtualized layers can interact with each other. And your OS is protected completely. But is SVS perfect?

Yes and No.

There is still a big trap built in -- by design -- that should be carefully handled.

SVS uses Excludes to exclude various files from a layer. This prevents users from losing data. But this is also the trap.

In the latest version Altiris offers Global Excludes. To prevent users from losing data, global excludes are set up to exclude everything by many users. But there the Virtualization ends.

Users that use this will see that lots of files that belong to the virtual layer are staying resident in your OS. These are files that are used by the application to perform some tasks, and therefore Global Excludes sees them as user data and does not take it inside the layer anymore. This ends up your quest against DLL hell. You first managed to win the struggle with the DLL hell, and then you make one simple setting to end it. Global exclude c:

The disadvantage of SVS is that it is not multi-user aware. So it could not be used in a server-based computing environment.

DVS4SBC

Then DVS4SBC (DeltaISIS Virtualization Solution 4 Server Based Computing) came to market. DVS4SBC makes SVS fully multi-user aware and it brings enhanced memory usage to the server.

Where Microsoft Softgrid is very cheap in a professional organization, it costs more to build, stream and maintain packages.

One of the biggest disadvantages of Softgrid is the layer visibility. Two layers can not work together to get you on the job.

In SVS this is the biggest advantage.

The Best of All Worlds

So in my quest for true virtualization, I decided to use best of all worlds.

I use VMware to virtualize my operating systems. I put Citrix on the VMware machines to deploy the resources to my users. I use DVS4SBC together with SVS to get my software virtualized to the Citrix server. I use DVS together with SVS Pro to stream software to my local machine. And with VPN connectivity, the software can be accessed in a secure manner.

My quest is ended for now, by using the perfect combination, but I still don't know if it is really virtualize, isolate, or whatever.

But it runs, is cheap, brings me back in control of software management. And prevents me from staying hours and hours in the dungeons of my company.

Regards Erik

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