When you analyze your disk data layout, consider zone bit recording.
All of Sun's current disks (except the 207 Mbyte disk) use this type of encoding which uses the peculiar geometric properties of a spinning disk to pack more data into the parts of the platter closest to its edge. This results in the lower disk addresses (corresponding to the outside cylinders) usually outperforming the inside addresses by 50 percent.
Put the data in the lowest-numbered cylinders.
The zone bit recording data layout makes those cylinders the fastest ones.
This margin is most often realized in serial transfer performance, but also affects random access I/O. Data on the outside cylinders (zero) not only moves past the read/write heads more quickly, but the cylinders are also larger. Data will be spread over fewer large cylinders, resulting in fewer and shorter seeks.