The ways of measuring drive performance

Higher performance in hard disk drive comes from devices which have faster performance characteristics.

  1. Access Time: The access time or response time of a rotating drive is a measure of the time it takes before the drive can actually transfer data. The factors that control this time on a rotating drive are mostly related to the mechanical nature of the rotating disks and moving heads.
  2. Seek time: With rotating drives, the seek time measures the time it takes the head assembly on the actuator arm to travel to the track of the disk where the data will be read or written.
  3. Short stroking: Short stroking is a term used in enterprise storage environments to describe an HDD that is purposely restricted in total capacity so that the actuator only has to move the heads across a smaller number of total tracks.
  4. Rotational latency: Rotational latency (sometimes called rotational delay or just latency) is the delay waiting for the rotation of the disk to bring the required disk sector under the read-write. It depends on the rotational speed of a disk (or spindle motor), measured in revolutions per minute (RPM).
  5. Power consumption: Power consumption has become increasingly important, not only in mobile devices such as laptops but also in server and desktop markets. Increasing data center machine density has led to problems delivering sufficient power to devices (especially for spin-up), and getting rid of the waste heat subsequently produced, as well as environmental and electrical cost concerns (see green computing).