Caching and tiering promise to hide the performance cost of spinning disk – but both rely on predicting the unpredictable, and the slowest tier always waits.

When performance capacity drives storage decisions, waste is the inevitable result – stranded terabytes, short-stroking, and a growing gap between what disk holds and what it can actually deliver.

Spinning disk hit its performance ceiling at 15k RPM over two decades ago – and physics, aerodynamics and economics mean it’s staying there. The consequences for latency are unavoidable.

Disk drives displaced tape by giving the read/write head the freedom to move – trading sequential dominance for random I/O capability. Understanding that physical design is where disk's performance story begins.