Disk Drives' Micro-Vibration Problem
Hard disks are a lot more sensitive than their name implies: They don’t like to be shouted at. Just ask Sun Microsystems engineer Brendan Gregg, who posted a YouTube video in which he yells at a rack of hard drives and then shows the corresponding increase in latency, the time it takes a drive to read and write information. The devices consist of a small arm hovering nanometers above a fast-spinning disk, and just as a record player will skip when bumped, the drives goof up when subjected to so-called micro-vibrations caused by sound waves or nearby movements.
That’s not a huge problem for a single laptop running Excel, but Internet giants such as Google and Facebook are increasingly stocking their data centers with racks of consumer hard drives to keep costs down. By not taking into account the loss of performance caused by micro-vibrations, the technology companies are costing themselves as much as they save, according to Stephen Sicola, chief technology officer of Xiotech. “You’re wasting money because you’re breaking things when you don’t need to,” he says. Google spokeswoman Kate Hurowitz declined to comment. Facebook spokesman Michael Kirkland says vibration is “not a major issue in our facilities.”
Xiotech is among the startups claiming to have a solution. Fixing vibration doesn’t require exotic materials, just well-designed cases and simple mountings that will cushion the drives, says Sicola. Along with other veterans of hard disk maker Seagate Technology, Sicola founded Xiotech to sell stiffened steel racks with rubber grommets that largely eliminate the impact of vibrations, he says. In a demonstration, Xiotech-shielded hard drives didn’t show any performance hiccups until blasted with music played at more than 140 decibels—about the volume of a jet engine.
Green Platform of Mountain View, Calif., offers another way to cushion storage arrays. Its founder, Gus Malek-Madani, began his career designing centrifuges at a biotech company. About 10 years ago he formed a company that used carbon fiber mounts to isolate high-end audio systems from vibration. Green Platform is adapting that idea for the data-center world. Malek-Madani rents out the racks and corresponding software to measure the impact of vibrations for $1,500 to $2,000 per month, and says they save about $5,500 worth of energy and equipment per rack per month.
The hard part is convincing companies that the problem exists. “If you go to a data center and ask them if they have a vibration problem, they’ll ask you, ‘What are you talking about?’ ” says Madani. Disk drives have traditionally been so cheap that companies simply toss them when they fail, though prices have risen 20 percent in the wake of flooding north of Bangkok, where many are manufactured. “The first challenge for anyone doing anything about this is you’ve got to make people care,” says Mark Peters, an analyst for IT advisory firm Enterprise Strategy Group. “It’s something that we’ve lived with for so long.”
Not all data center operators are unaware. Microsoft doesn’t use the cheapest drives or cram storage devices into large arrays. And it checks and maintains equipment to mitigate against the impacts of vibration, according to Dileep Bhandarkar, chief architect of Microsoft’s Global Foundation Services. “You have to strike the right balance between going too far to save costs and running into issues,” he says. “We avoid this problem as opposed to having to fix it afterwards.”