User Manual

A white paper issued by Siemens  September 2015

Figure 5: Noise sensitivity of four 1 TB nearline storage HDDs, Siemens Corporate Technology, 2009

*) LZFmax per third-octave band

The figure above shows the sound level at which the performance of the HDDs was reduced by 50

percent (yellow). The test results show that excessive noise can have a negative impact on HDD

performance (red). For hard disk drives, this level typically starts at 120 dB (within a third octave),

but for certain HDD types and frequencies, the negative impact may begin at levels below 110 dB.

All the HDDs were found to be highly sensitive to noise in the frequency range of 500 Hz to 8 kHz

and above. As expected, some resonating frequencies were found to have an even stronger im-

pact (not shown here).

Random tests in the first quarter of 2014 with current 2 TB to 4 TB HDDs confirmed the sensitivity

parameters determined in 2009.

1.1.4 Vibration/structure-born sound

Vibration is closely linked to the noise issue. The hypothesis is that sound causes vibrations in

the HDD case that are ultimately transmitted to the disc spindle and head assembly, causing misa-

lignment of the read/write heads to the data tracks.

Vibration caused by imbalance and the head motion of HDDs as well as by the imbalance of

ventilators exposes HDDs to structure-born vibration in the storage system chassis and cabinets.

These vibrations alone can cause additional stress to the HDDs or can even reach critical levels.

Because there are many different designs of storage system chassis and cabinets on the market,

the issue of vibration caused by noise as well as structure-borne vibration has not yet been fully

investigated.

Noise sensitivity of HDDs

during tests

Normal performance

Reduced performance

Temporarily out of order

Dotted line =

50 percent performance when

exposed to pink noise at this level

in dB(Z)