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Delaying Hard Drive Power Up?
Bamfarooni asks: "Does anyone know of a device that will delay
powering up your hard-drives (or other internal devices)? We're trying
to put a pile of IDE disks into a big disk server but the spin-up
power for these disks is about 3x the maximum operating current.
Rather than put in something really big like an 800W power supply, if
we could just put something in-line that delayed the power through
specific connectors for ~1 second, then we could mange with the
built-in power supplies we already have." An interesting thought,
but wouldn't the BIOS need to be aware of whatever delay is introduced?
Otherwise it may interpret the delay wrongly and think that the drives
on the IDE chain have timed out and are faulty.
I know you probably realize that SCSI does/can do this. But I also know that you're probably using IDE because SCSI drives of comparable size will be like twice the cost.
But, you might look into a hybrid solution by using SCSI-to-IDE converters. I'm not sure if the 'delay spinup' feature is dependent on the drive itself or just the SCSI Host Card, but if it's the SCSI card that does delayed spinup, you might be able to do this.
Something like this is what I'm thinking about. Of course, they charge $70 each adapter (which means per drive, too) -- though you may be able to get a better deal somewhere else.
Also, depending on OS, have you looked into a firewire solution? THey don't delay spinup, but you can use external power with them (via the drive or the hub/repeater).
Hilary Rosen's speech was about her love of money and her desire to roll around naked in a pile of money.
Some motherboards settings (including a crappy Gateway i was messing with yesterday) have a "harddisk predelay" that you can adjust a time period before it polls for harddrives.
Adjusting that setting higher would address that.
Why not just use two or three 300 watt power supplies? A top quality 400 watt PSU is can be found for about $40-$60. Just get 2 for $80. Much cheaper than an 800w power supply (which doesnt even exist!)
:). Or, you could use an AT power supply, which doesn't need a motherboard in order to operate. Im not sure if the BIOS will recognize a drive that is already powered up, though?
I forget what pins... but if you short two of the pins on the ATX motherboard connector, it powers up. In theory all you would need to do is make sure the drives all power up at roughly the SAME time. This could be easily accomplished with a few bits of wire and a doorbell
Some older bioses used to be able to init the hard drives at a timed delay. This was due to the fact that the hard drive wouldnt spin up fast enough to be recognized. This is no longer a problem, and has been omitted from all modern bioses.
Finally, the timed spinup idea isn't really a good idea. If several hard drives spin down, and then all resume at the same time, it would overload the power supply, causing damage to the PSU, and most likely other (expensive) components along with it.
Long and short: Use 2+ power supplies, attach both of them to a doorbell (or case button, but those are usually too small to attach two pieces of wire), and they will both power up synchronously.
-- If you try to fail and succeed, which have you done? - Uli's moose
The folks at PC Power and Cooling have this monster which, altough comprised of 2 separate hot-swappable 420W PSU's, is supposed to be able to deliver 840W peak.
Any good electronics shop or catalog should have 120v relays with a preset delay on them (usually 5-20 seconds). I have several 5 second ones on a rack of AV gear where I work, ganged together so equipment turns on 0, 5 and 10 seconds after the switch is thrown.
They're pretty cheap ($20), and if you've got drives on a separate powersupply, hooking it up should be trivial.
BBK
SCSI does this automatically...drive spin delay can be totally disabled until a START UNIT command is issued from the controller, or set to delay spinup 12sec * SCSI ID.
Very handy for big arrays.
JWK
Use SCR's at every drive with a Resistor/Capacitor to time the gate. Each drive down the line would have a longer Time Constant. A .3 to .5 voltage drop shouldnt cause any problems.