disk with high frequency noise only on FreeBSD

[James Phillips]

> Date: Fri, 11 Dec 
2009 23:52:50 +0200 > From: ly4uk Root <ly41k at ukr.net>
> Subject: disk with high frequency noise only on FreeBSD
> To: freebsd-questions at freebsd.org
> Message-ID: <1260568370.99298.49.camel at localhost>
> Content-Type: text/plain
<SNIP!> 
> cleaning), but drive is still squeaking. Now I'm using
> freebsd 8.0, not
> fresh install, got it from seven release (at almost year
> ago) by
> tracking stable branch. All noise came exactly in one
> reboot while
> upgrading to 8.0-RC2.
> So, it would be interesting to get Your answer about
> possible
> solutions(if You know such) or maybe some comments(if
> don't). I will be
> very happy for that, many excuse for disturbance.
> 

Now, this post is interesting. I'm sure many people with a software 
background may be tempted to write this report off as completely 
implausible. The truth is even "non-moving" parts such as inductors 
and possibly capacitors can move in response to an applied signal. 
For example, my ADSL modem with no moving parts makes an audible 
hissing noise louder than the (80mm) fan noise of my BSD server.

I have no idea what would be causing this in 8.0-RC2, but I can 
suggest what to look for: anything polling the drive in the audible 
frequency range (20 to 20 thousand times per second). Another 
possiblity is any action the repeats at that rate, but was not 
present in ealier versions. The timer interrupt is in that range, but 
other systems like GNU/Linux (before the tickless kernel) and Windows 
use a similar timer. 
To the original poster: you say this is a laptop. How do you know the 
noise is coming from the hard drive and not some other component like 
the speakers/Network card/fan? 
Regards,

James Phillips


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