Big Boxes

I like to work in an Agile project environment. Recently I have found myself in the happy position of being able to work for a client who is really buying into the whole Agile movement. The client is a very big telco, so its systems need to be... well... very big too.

This presents a few problems. One which is on my mind right now is how to size and budget for buying suitable hardware to host our new system. At the moment, we have tackled some of the lower volume products but in later cycles we will be doing some really big stuff against some really imperative deadlines.

We dont yet have detailed requirements for the big stuff (it's Agile, remember?), but we need to put a box in place which is going to have to cope with them. How to do it? Here are a couple of options...

• Rely on commodity boxes and horizontal scalability. That way, we can roll out incrementally and we dont need to know up front how many boxes we will eventually need. This works well for the app server tier, but is of less help for the database tier.


• Get the best picture we can of upcoming volumetric requirements (I dont think we can bet on 'You Arent Going To Need It') and pick a hardware range with enough memory, processor etc expansion capacity to support the eventual need.

To further complicate matters, we need to budget for floor space in the data centre - if we get it wrong, we may find that our boxes are hundreds of miles apart, which isnt going to do much for latency.