
Intentional Acoustic Interference Damages Availability and Integrity in HDDs [pdf] - weirdo1
https://spqr.eecs.umich.edu/papers/bolton-blue-note-IEEESSP-2018.pdf
======
myself248
[https://www.youtube.com/watch?v=tDacjrSCeq4](https://www.youtube.com/watch?v=tDacjrSCeq4)

Ten years, man...

~~~
lowry
Only on Hacker News the first comment is the best comment. Long life Brendan
Gregg, the guest star of the above video and our beloved Linux Performance
guru!

------
TwoNineFive
I recently had a problem where a hard drive was being negatively impacted by
the noise caused by cooling fans in the chassis.

The hard drive was a Toshiba P300 3TB model HDWD130XZSTA. In the last year or
two, since Toshiba's corporate troubles have gone on, they have started to
price their hard drives more competitively. They seem like pretty nice drives
in regards to performance and noise, but I discovered that this model at least
seems to be susceptible to errors when subjected to nearby acoustic
noise/vibration.

The server was a generic 1U with six 40mm fans in the center behind the hard
drives. When the fans run at full speed they are really loud -- like seriously
hurting your ears loud.

I first noticed something was wrong when some SMART errors developed on one of
the drives, indicating a failure. I RMAed that drive and then got a new one,
but the linux mdadm RAID rebuild was insanely slow. Further tests showed that
the new drive was performing terribly and I went through the process of
troubleshooting.

It took awhile before I finally figured out it was the fan noise causing it,
but you could really see the transfer speed ramp up/down when I plugged the
fans in/out. When the fans running at full speed, the drive read rate (hdparm
-h) would drop down to 1MBps or even less, whereas they would go up to
175-190MBps normally. The read errors were SO bad that it must have triggered
a SMART failure on the previous drive.

I've been a sysadmin for about 20 years now in datacenter environments and
this was the first time I've seen an effect this substantial.

It's noteworthy that this same chassis has two Seagate drives in it which
didn't suffer any negative performance issues from the noise.

I guess that's what I get for using desktop class drives in a server.

~~~
PhantomGremlin
Are you sure it was acoustic noise?

I don't know how fans actually implement variable speed. But I can think of
several methods that would generate lots of electrical noise. Fan
manufacturers have an incentive to build as cheaply as possible, so I doubt
they take too many steps to mitigate crap they put out on the power lines
and/or radiate from their speed controller.

~~~
TwoNineFive
Well, like you said, you don't even know how fans work.

~~~
Doxin
Fans implement variable speed through PWM which is a square wave and therefore
rather noisy.

------
jlubawy
For what it's worth Western Digital does extensive testing of drive
performance under audio vibration, especially on mobile drives that are likely
right next to a laptop speaker.

~~~
digi_owl
And if you check page 7 of the PDF there is a small table that indicates that
this has to be at around 120dB to have an effect. I do believe that is up
around the point where you risk physical pain and instant hearing loss.

~~~
marshray
Bad news for UBeam then.

~~~
digi_owl
Well they came across as a pipe dream from day one...

