Are blade servers for everyone?

MVDirona

This note describes a conversation I’ve had multiple times with data center owners and concludes that blade servers frequently don’t help and they sometimes hurt, easy data center power utilization improvements are available independent of the blade server premium, and enterprise data center owners have a tendency to buy gadgets from the big suppliers rather than think through overall data center design. We’ll dig into each.

In talking to data center owners, I’ve learned a lot but every once in a while I come across a point that just doesn’t make sense.  My favorite example is server density.  I’ve talked to many DC owners (and I’ll bet I’ll hear from many after this note) that have just purchased blades servers.  The direction of conversation is always the same. “We just went with blades and now have 25+kW racks”. I ask if their data center has open floor and it almost always does. We’ll come back to that.  Hmmm, I’m thinking. They now have much higher power density racks at higher purchase cost in order to get more computing per square foot but the data center already has open floor space (since almost all well designed centers are power and cooling bound rather than floor space bound).  Why?

Earlier, we observed that most well designed data centers are power and cooling bound rather than space bound.  Why is that anyway?  There is actually very little choice.  Here’s the math: Power and Cooling make up roughly 70% of the cost of the data center while the shell (the building) is just over 10%. As a designer, you need to design a data center to lasts for 15 years. Who has a clue of the needed power density (usually expressed in W/sq ft) 15 years from today? It depends upon the server technology, the storage ratio, and many other factors.  The only thing we know for sure is we don’t know and almost any choice will inevitably be wrong.  So a designer is going to have too much power and cooling or too much floor space.  One or the other will be wasted no matter what.  Wasting floor space is a 10% mistake whereas stranding power and cooling is a 70% mistake.  This 10% number applies to large scale data centers of over 10MW not in the center of New York – we’ll come back to that. Any designer that strands power and cooling by running out of floor space should have been fired years ago.  Most avoid this by providing more floor space than needed in any reasonable usage and that’s why most data centers have vast open spaces. Its insurance against the expensive mistake of stranding power.

Check out this great post with some relevant and valuable comments. Blade servers are by no means the answer to all your issues (business and IT related). You need to think about how you’re implementing the technology, how it coupled with your business processes, the way you and your IT works, will work in providing the IT you want for your business. Implementing a virtual infrastructure for example can bring real benefits in delivery and availability, however your billing, your support and issues of ownership need to be discussed, resolved and processes created as you implement the technology - the what if scenarios.