Drop-Testing Drives

I don't know if the it was the heat or just a lack of better things to do, but drop-testing drives seems to have replaced Vespa jousting as the geek sport of the month in August. First Popular Mechanics magazine ran a portable USB hard drive drop test, subjecting several drives to higher and higher drops until they failed. Video here. Then Samsung tossed one of its laptop SSDs off the roof of its building in sillycone valley and, wonder of wonders, it booted the laptop they screwed it into. Video here.So other than a few laughs, what value do demonstrations like this have? What can we learn and how can we adjust our practices?

The first lesson we should all accept is that the 2.5-inch drive designed for laptop use is substantially more rugged than the drives designed for desktop or server use. A typical laptop drive is rated at 350 Gs when operating and 900 Gs when powered down. It's 3.5-inch equivalent is rated just 70/300.

Part of the reason laptop drives can, as John Cameron Swayze used to say, take a licking and keep on kicking, is the ramp unload mechanism that, like the tonearm rest on a turntable (that, kiddies, is what we used to use to play music before CDs), removes the drive's heads from the platters at power down. Most 3.5-inch drives just let the heads land on a non-data bearing section of the platter.

Add in Hitachi's accelerometer that can detect when the drive is in free fall and retract the heads in 140 ms (or about 4 inches of fall in Earth's gravitational field of 32 ft/s/s) and even a running drive can handle a bunch of shock. Since the SSD has no moving parts at all, it can handle 1,500 Gs whether it is powered up or not.

So those of you using USB drives as backup targets and schlepping them around to get your data off-site should be using 2.5-inch drives.

While the Popular Mechanics testing was fun to watch, you really can't draw any conclusions from it. They only used one sample of each drive model and just tossed them in the air, so the drives that failed may have landed in the direction they were most vulnerable to shock and the ones that passed safely may have landed on their backs, where the air trapped under the drive provided some cushioning.

All in all, good, clean fun.