The USB-drive time bombOriginally published 2005 in Atomic: Maximum Power Computing Last modified 03-Dec-2011.
Storage, as I've written before, is a problem that bedevils the modern nerd.
We've all got our stories about how we wondered how we'd ever fill that new 8Gb Fireball for our K6 that cost as much as a new set of excellent tyres, or that 1Gb SCSI drive for our Amiga that cost as much as a good used Kingswood, or that five million character 350 Disk File for our IBM 305 that would have cost as much as a Formula One racing team (one of the good ones), were it not for the fact that our only option was to lease the whole rig for an inflation-adjusted $US22,000 per month.
Especially when you've decided to leapfrog the ghastly organisms at the movie and TV studios and download someone else's HDTV rip of whatever interests you. Oh, those upstanding corporations promise that one day they'll sell it to you in some stupid DRMed format that you may have to buy a whole new computer/TV/set of eyeballs to view, and won't be able to back up.
Hmm. Tough choice.
Hence, arbitrary gigabytes of space eaten up. Oh, sure, maybe some of you are doing digital video or scientific computation or monster database work. Suuuuure. No, really, I believe you. I do.
Anyway, because speed isn't terribly important for domestic drive arrays, you can get away with doing it the super-simple way - USB drive boxes. USB 2.0's got decent bandwidth; if you've got a separate server machine connected to your other boxes by anything slower than PCIe gigabit Ethernet, USB 2.0's literally more than fast enough. And drive boxes are cheap and easy to set up, and you can just stack those suckers up pretty much forever.
I wouldn't try pushing anywhere near the 127-device-per-root-port USB limit, but even if you only install a mere 12 devices per controller, you'll be able to set up ludicrous numbers of disks. One built-in controller, a couple more in PCI slots, a mere 300 formatted gigabytes per drive; there's ten and a half terabytes, right there, at a price that'd make a datacentre operator from 1990 clutch his chest and fall over backwards.
But there's a trap here, even if you're a normal person who's only considering one or two external drives.
Consumer hard drives, you see, have short warranties (OK, OK, except Seagates, but they exclude their own external drives from that warranty...). There's a good reason for that.
That reason is not that the drive manufacturers want to reduce the overall cost of the warranty program. Sure, people who buy drives may try to install them while they're sailing on the high seas and covered with a crackling aura of St Elmo's Fire, and hard drive manufacturers certainly are annoyed about drives that've been killed by electrostatic discharge due to improper handling by the user getting returned under warranty. But the overwhelming majority of the world's hard drives are installed by people - or possibly robots - who do it the right way. The unfair warranty returns are actually a drop in the bucket.
The real reason for short warranties is that consumer drives wear out.
In a typical business-computer situation, where the skinflints in the purchasing department have made sure that every PC in the place is short of physical memory and so flogs its drive non-stop for eight hours a day, a substantial fraction of those drives can be expected to last two years or less. Three is definitely pushing it. Support people in such companies are used to doing drive replacements, and would probably have to do significantly fewer if the computers had more RAM.
People with the misfortune to have bought a base-spec Dell desktop are in the same situation, but so are a lot of geeks, who make up for their ample system RAM by spending a lot more time in front of the computer doing stuff that hits the disk. Heck, just downloading all that video will stop the disk receiving it from ever spinning down.
The way you make consumer drives last is by not using them. If they're spun down in standby mode, they're not wearing out. Even if a drive's kept in an anti-static bag in a cupboard, it won't last forever, but it's usually the physical components like the spindle and head assembly bearings that kill a drive after two years. When they ain't movin', they ain't wearin'.
Getting hard drives to spin down on any modern computer is, of course, easy. You can set the spin-down time to a really aggressive laptop-on-batteries five minutes or so, if you like. Consumer drives spin up fast (server drives don't), so there's no huge performance penalty to pay for doing that.
But if you're using USB drive boxes, their own little bridge interface is what decides when the drive spins down. Or, more accurately, if the drive spins down.
A lot of cheap external boxes - practically all of them, I think - never spin the drive down at all. They keep spinning the darn thing all day and all night, and keep spinning their cheap-bearinged cooling fan too, for that matter; that'll probably give out even sooner than the drive does, but is of course easier to replace, or hack around with some unsightly external-fan contraption.
Fancier Network-Attached Storage gadgets spin down their drives, of course. Buffalo Technology's somewhat pricey TeraStation, for instance, apparently has a fixed 30 minute spindown timer - though good luck finding anything about it in the manual. But the only way you can get most USB boxes to spin down is by yanking the power.
Which, of course, you can do. Run all of the drive box plugpacks from a Christmas tree of powerboards hooked to one switched outlet - which is a bad idea for high powered devices, but fine for the modest demands of hard drives - and you can toggle the lot of them on and off at will. USB won't get upset over that, though it is of course less than wise to cut the power in the middle of a write operation.
But if you don't take this sort of precaution, and leave the drives online all the time, don't expect them to last.