05 Feb 2008

Quasi-DIY FireWire Swappable Drive Enclosure

I’ve wondered for a while if it’s possible to construct a swappable external hard drive by putting one of those cheap removable IDE drive drawers inside a 5.25” external FireWire enclosure, but not enough to actually go out and buy all the parts and then have to return them when it didn’t work. However, thanks to the wonder of the Internet I was recently able to pick up both pieces for under $20 from the clearance section of Geeks.com.

Short answer: it actually works. (Even spindown.) For twenty bucks plus shipping and a spare IDE drive, you can make yourself a functional analog of a Quantum GoVault, suitable for all sorts of disk-based backup tasks.

In retrospect, I’m not sure why I thought it wouldn’t work. I think I was assuming far more complexity on the part of the IDE drive drawer than actually exists; I figured they were an actual backplane with some logic to let you hot-swap the drive. In reality they’re nothing more than a big Centronics connector for the power and IDE connections, a few LEDs, a fan, and a key-operated on/off switch to keep you from ripping the drive out while it’s spun up. It doesn’t get much more basic than that. Once you have the drive inserted and locked, the FireWire bridge is none the wiser.

Where things get messy is if you actually try to hot-swap the drive while it’s in use. Because the FW bridge isn’t designed for hot swapping on the IDE side, bad things tend to happen when you remove the drive and reinsert it while the FW bridge is on. However, as long as you power off the entire external enclosure (rather than just the drive), then swap drives, then power back on, everything works nicely. I think of it as sort of a ‘warm-swap.’

I prefer the drive-tray-and-enclosure solution to just buying multiple 3.5” enclosures because the 5.25” one – unfortunately no longer available from Geeks.com but easily found elsewhere under its model number, “PM-525F2-MOS” – has significantly better heat characteristics than most cheap 3.5”s (it’s aluminum and has a fan, for starters; the unvented plastic ones eat drives for breakfast), and the cost per additional drive is much lower.

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