wow, i totally missed that one.
hamei is partly right. this acquisition is not an sgi preogative, it's clearly rackable strategy. COPAN is known for building 'green' storage systems. which is a big strategy driving rackable technology (what there is of it, packaging in my mind has little or no IP). the systems operate by maintaining a certain percentage of the drives spun down to reduce the power foot print of the system. this works fairly well since many, if not all, workloads exhibit strong locality of reference, and large skew. what does this mean? a large portion of IO is too a small percentage of devices, and within those devices there is a small percentage of data accessed. the trade of you have to make is in not being able to take advantage of wide striping. as a result you have a power efficient system with low performance, with a small number of useful power states. this reduces the applicability of the system as a whole to specific purposes. it's a pretty novel implementation so far, but soon will become just another feature of other systems as green gets more momentum, which is coming like a tidal wave. so this is a marginal purchase over all at best.