ABSTRACT
Recall from the discussion in Chapter 6 on information lifecycle management (ILM) that tiering is the separation of storage devices into classes according to the characteristics of the storage devices themselves. The performance of different classes of storage devices (in the sense of speed) tends to correlate with the cost per unit of storage. That makes sense: All other things (such as availability and reliability) being equal, higher-performance devices would otherwise drive lesser-performing devices off the market if the cost per unit of storage were equivalent, because the extra performance would be “free.”
