<Tr> <Td> 10,000 </Td> <Td> 3.00 </Td> </Tr> <Tr> <Td> 15,000 </Td> <Td> 2.00 </Td> </Tr> <P> 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 head . It depends on the rotational speed of a disk (or spindle motor), measured in revolutions per minute (RPM). For most magnetic media - based drives, the average rotational latency is typically based on the empirical relation that the average latency in milliseconds for such a drive is one - half the rotational period . Maximum rotational latency is the time it takes to do a full rotation excluding any spin - up time (as the relevant part of the disk may have just passed the head when the request arrived). </P> <Ul> <Li> Maximum latency = 60 / rpm </Li> <Li> Average latency = 0.5 * Latency Time </Li> </Ul>

Scsi hard drives can spin at a maximum speed of