Hitachi ULTRASTAR 15K450 HUS154530VLF400 - Manual (Page 59)

Hitachi Ultrastar 15K450 (FC-AL) Hard Disk Drive Specification
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13.0 Acoustics
13.1 Sound power levels
The upper limit criteria of A-weighted sound power levels are given in Bel, relative to one pico watt, and are shown in the
following table. The measurement method is in accordance with ISO-7779.
Table 23: A-weighted sound power levels
Background power levels of the acoustic test chamber for each octave band are to be recorded. Sound power levels are mea-
sured with the drive supported by spacers so that the lower surface of the drive is located at a height of 25 cm from the cham-
ber floor.
No sound-absorbing material shall be used. The acoustical characteristics of the drive subsystem are measured under the
following conditions.
Idle Mode:
Powered on, disks spinning, track following, unit ready to receive and respond to host commands.
Operating Mode
Continuous random cylinder selection and seek operation of the actuator with dwell time at each cylinder. Seek rate for the drive
is calculated per the formula below:
Ns =average seek rate in seeks/sec where:
Ns = 0.4 / (Tt + Tl)
Tt = published random seek time
Tl = time for the drive to rotate by half a revolution
Model Mode
A-weighted sound power level (Bel)
Typical Maximum
450 GB
Idle 3.7 4.0
Operating 4.3 4.7
300 GB Idle 3.7 4.0
Operating 4.3 4.7