For the 153rd reading group paper, we read something very different this time: “Deep Note: Can Acoustic Interference Damage the Availability of Hard Disk Storage in Underwater Data Centers?” This HotStorage short paper explores the possibility of using soundwaves to attack underwater data centers. In particular, the paper shows how magnetic disks can be disrupted by sound, causing them to degrade or even outright stop working, leading to failures of whatever systems were relying on these disks.

As the paper suggests, the idea of using sound to impact HDDs is not novel. Magnetic disks are mechanical devices with very tight tolerances for placing magnetic read and write heads over the plate. The sound can vibrate the disk enough to prevent this alignment within the required tolerances, causing the disk to malfunction.

This paper takes the “shouting at the disk” approach up a notch by considering this problem in underwater data centers. See, the sound has different properties in the water. The underwater placement of hardware also needs a water-tight enclosure, which may change the sound/vibration characteristics passed into the hard drives. This poses the question of whether such data centers may be vulnerable to a remote attack using sound.

For their experiment, the authors tried a rather simplistic setup. They used a plastic aluminum box (as the data center vessel/enclosure simulant) submerged in water with a hard drive either directly touching the “floor” of the enclosure or mounted on an HDD rack (to simulate server racks) placed on the “floor.” Pool speakers played the sounds of various frequencies.

The results show that it is possible to slow down the magnetic disks, but maybe there is hope. While the authors managed to render the HDD unusable for the duration of the attack, the effective range was small — just a few dozen centimeters (i.e., ~10 inches). I speculate that combined with a proper pressure vessel for the data center with good insulation/dampening materials, this type of attack may not be that big of a deal. That being said, the power of the underwater pool speaker is not comparable to military sonar equipment, which has more range and penetrative power.

Please read the paper for more details. It is an easy, fun, and interesting 5.5 pages!

Reading Group

Our reading group takes place over Zoom every Thursday at 1:00 pm EST. We have a slack group where we post papers, hold offline discussions, and most importantly manage Zoom invites to paper presentations. Please join the slack group to get involved!