Acoustics; Sound Power Level - IBM DYLA-28100 - Travelstar 8.1 GB Hard Drive Specifications

5.6 Acoustics

5.6.1 Sound Power Level

The criteria of A-weighted sound power level is described below.
Measurements are to be taken in accordance with ISO 7779. The mean of 40 drives is to be less than the
typical value. Each drive is to be less than the maximum value. Drives are to meet this requirement in both
board down orientations.
A-weighted Sound Power (Bels)
Idle
Operating
Background power levels of the acoustic test chamber for each octave band are to be recorded.
Sound power tests are to be conducted with the drive supported by spacers so that the lower surface of the
drive be located at 25 + / - 3mm height from the chamber floor. No sound absorbing material shall be used.
The acoustical characteristics of the disk drive are measured under the following conditions.
Idle mode :
Power on, disks spinning, track following, unit ready to receive and respond to control line com-
mands.
Operating mode :
Continuous random cylinder selection and seek operation of actuator with a dwell time at each
cylinder. Seek rate for the drive can be calculated as shown below.
Ns = 0.4/(Tt + T1)
where:
Ns : Average seek rate in seeks/s.
Tt : Published seek time from one random track to another without including rotational latency.
T1 : Equivalent time, in seconds, for the drive to rotate by half a revolution.
30
O E M Specifications of DYLA-2xxxx 2.5 inch H D D
Typical
3.7
4.0
Maximum
4.0
4.3