Systems engineer Louis Foler is a consultant for CDW Corp., the online systems retailer based in Vernon Hills, Ill. Foler is in the field regularly helping customers find the best hardware solutions for virtualizing in their data centers. He talked with SearchOpenSource.com recently about what IT managers want to know about virtualization, when blade servers are best and who should probably avoid them.
SearchOpenSource.com: What are some common questions you hear from customers who want to virtualize in their data center?
Louis Foler: A lot of the customers I work with come to us and need input because they don't know if they need a big hairy box or a bunch of individual blades to virtualize on. They are basically just trying to figure out how best to run the virtualization technology. In many cases, they want to virtualize as a means to replace older physical machines or they are expanding significantly in their work center and are concerned about space. You can often use existing hardware for server virtualization. But most of the time, these projects go on new hardware.
Why are blade servers often suggested as complimentary servers for virtualization?
Foler: You don't need blades to virtualize. You can virtualize on any sever you want. Because virtualization software is simply something you add to a server, you can do that on any type of server.
I like to sell virtualization software with blade servers because the blades are like a self- contained system on their own. Blade technology consists of a chassis with components it shares with the blade servers inside. For instance, the power supply is not on the servers, it's in the chassis. So, because of this design, these blade centers are like self-contained systems and work great with virtualization technology.
When virtualized on blades and with certain virtualization tools, you can move existing applications from one physical server to another and quite easily troubleshoot a problem blade server. For instance, if one blade has a problem, you can move the virtualized application to another blade server in the chassis. You can then take out the problem blade, troubleshoot, put the blade back in the chassis and move the application back to its previous location. The end user will never even know there is a problem. This is a lot easier to do with a blade than if you are dealing with a large traditional server -- mainly because of its size.
What are some of the challenges of blade servers, and whom would you not recommend them to?
Foler: Blades usually have minimal hard drive space. If you are trying to replace your traditional servers with blades to run something like a SQL server or other large database, you might run into problems getting all the storage you need. In this instance, you would need external storage. Sometimes when you bring that up with a customer, they are not ready for external storage, so blades would not be right for them.
Which customers are they right for?
Foler: I recommend them to anyone who is looking to replace or add more than seven servers to their data center. If an account manager comes to me and says 'I have this customer looking at blades,' my question is: 'How many servers are we talking about now and will it be in the next six months?' If you are just looking for two or three new servers and your concern is space, blades aren't the best option because you would take up more space with the blade chassis than if you simply had two or three individual traditional servers.
When someone tells me a customer is looking at seven, eight or even more servers, that is my first clue that blades are the right technology.
Foler: In terms of the types of applications that are right for blades, an example would be if you want to put a bunch of terminal services for e-commerce on blades -- that's an excellent fit. With larger databases, you can sometimes run into an external storage issue.