Identifying disk activity

Polytropon freebsd at
Sun Aug 28 06:11:43 UTC 2011

On Sat, 27 Aug 2011 23:54:32 -0600 (MDT), Warren Block wrote:
> On Sun, 28 Aug 2011, Polytropon wrote:
> > Since I have installed my new system (FreeBSD/i386 8.2-STABLE),
> > I have found some kind of disk activity I've never had before
> > on my home system. As this PC is a very cheap product, it doesn't
> > have a HDD LED. Instead I have to listen to the disk.
> >
> > This is the strange sound: four groups of short "brrrrt" sounds
> > within a second, with a short pause between them.
> >
> > 	#####-----#####-----#####-----#####----- = 1 s
> >
> > This can be heared over several seconds, then silence. From
> > time to time, a "brrrt" sound appears for 3 seconds in one
> > long rush.
> That could be a "t-cal", thermal calibration.  Depends on the age and 
> model of the drive, some drives don't do it.  Could be other internal 
> drive activity.  WD drives like to park heads often, loudly, and for no 
> good reason.

I didn't mention it's a WD, how did you guess? :-)

% dmesg | grep ^ad
ad4: 305245MB <WDC WD3200AAJS-56M0A0 01.03E01> at ata2-master UDMA100 SATA 1.5Gb/s

Strangely, I didn't hear that sound when the system was running AMD64,
it seems to have appeared on i386 and _sometimes_ in conjunction with
Opera. I have removed the side panel of the PC box, but the sound
still sometimes can be heared. The disk doesn't become spectacularly
hot, but thermal problems are quite common to "modern" home consumer
hardware - and this special PC seems to be _very_ "modern".

I have used _many_ WD drives in the past, but none of them has even
made such sounds. Seems to be a "modern" feature.

> > Is there a way to force "synchronous disk activity"?
> Turning off soft updates will help, but not make disk writes 
> totally synchronous.

Can this be done easily (e. g. "tunefs -n disable <devices" in
SUM to the unmounted partitions), without data loss? I have to
admit that I've never tried that before.

Magdeburg, Germany
Happy FreeBSD user since 4.0
Andra moi ennepe, Mousa, ...

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