Hitachi HTS543280L9A300, HTS543212L9SA00 manual Performance characteristics, Command overhead

5K320 SATA OEM Specification

4.4Performance characteristics

Drive performance is c haracterized by the following parameters:

ŸCommand Overhead

ŸMechanical Positioning w Seek Time

w Latency

ŸData Transfer Speed

ŸBuffering Operation (Look ahead/Write Cache)

Note: All the above parameters contribute to drive performance. There are other parameters which contribute to the performance of the actual system. This specification defines the essential characteristics of the drive. This specification does not include the system throughput as this is dependent upon the system and the application.

The following table gives a typical value for each parameter.

Function
Average Random Seek Time - Read (ms)	12
Average Random Seek Time - Write (ms)	13
Rotational Speed (RPM)	5400
Power-on-to-ready (sec)	3.5
Command overhead (ms)	1.0
Disk-buffer data transfer (Mb/s) (max)	775
Buffer-host data transfer (Gbit/s) (max)	1.5 / 3.0

Table 4. Performance characteristics

4.4.1Command overhead

Command overhead time is defined as the interval from the time that a drive receives a command to the time that the actuator starts its motion.

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