How Seagate Tests Its Hard Drives

Other Testing

Welcome to the Longmont facility’s electromagnetic interference (EMI) lab, a necessary part of meeting FCC and other environmental electronics standards. Essentially, Seagate tests for three things here: 1) the electromagnetic energy emitted by a drive during operation, 2) the drive’s susceptibility to EMI and 3) a drive’s tolerance to electrostatic shock.

With the EMI detector shown below (red), Seagate measures emissions, in this instance from within a server enclosure. The receiver antenna can easily rotate in order to more accurately sense emissions on various polarities. Also, observe how the server and its table are mounted on a circular platform. This allows engineers to easily turn the server in different orientations so that many angles of emission can be observed.

And here we have the other side of the EMI coin, assessing EMI susceptibility. In anechoic chambers like these, furniture and accessories tend to be of wood or foam so as to lessen the risk of metal components reflecting EMI energy and skewing results. In fact, this is also the reason you see pyramidal foam lining the walls. Just as with soundproofing, these specialized foam blocks serve to absorb electromagnetic radiation and minimize signal reflections—hence the name: an-echoic.

Yes, the device below is exactly what it looks like: a tazer. Naturally, engineers can dial in their desired zap parameters, and the results both to the drive’s mechanics and data performance are studiously observed. As shown here, a technician administers an electrostatic shock to a tower PC, much as your hand might after dragging your feet across the carpet on a dry day. Yes, systems are supposed to be adequately grounded, but Seagate doesn’t want anything left to chance when it comes to drive reliability.

Speaking of soundproofing, acoustics can be a very important criterion for many storage applications, such as DVRs and some embedded systems. Even among desktops, we all know the annoyance of a drive that makes overly loud clicking during data seeks. The chamber below shows where drive samples pulled from the design process are tested to ensure that they meet acoustic spec requirements.

As you can see, many microphones are arranged in a specific array pattern. In other test setups, the bare system you see above might be removed. The microphones, each worth several thousand dollars with its preamp, are highly specialized for low electrical noise. The torso, or “head unit,” specifically measures sound quality (as opposed to a sound power number). The chamber itself, built on an independent concrete slab in order to isolate against ambient vibration. All told, the chamber and its contents represent hundreds of thousands of dollars invested. We mention this simply to convey the formidable efforts and expense that go into crafting a drive so that it meets that one little (but, to some customers, critical) acoustic spec on its product sheet.

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