Just an FYI... My disks take 2.5 amps on the 12V line (30 watts) to start. Someone else said his require 2.9 amps (34.8 watts). The above does not include the 5V line. 2 X startup wattage or amperage seems excessive. Power supply delivers 50% during startup, and 25% while the system is in use. Seems wrong to me. Guy -----Original Message----- From: Alvin Oga [mailto:aoga@xxxxxxxxxxxxxxxxxxxxxxx] Sent: Tuesday, December 14, 2004 6:55 PM To: Guy Cc: 'Brad Campbell'; comsatcat@xxxxxxxxxxxxx; linux-raid@xxxxxxxxxxxxxxx Subject: RE: Busted disks caused healthy ones to fail On Tue, 14 Dec 2004, Guy wrote: > My disk drives are rated to use 19.1 watts while active. > My disk drives also get very hot without forced air movement. > 14 such disks use 267.4 watts. That would give you 152.6 watts for > everything else. I bet your disks use less power than mine. I agree with > Michael, you may be exceeding the power rating of your power supply. an overworked power supply will fail "faster" for "wattage" ... using a sharp needle, "pop" ... that is NOT how "wattage works" - for a given voltage, you should be operating at 1/2 of its rated amperage - at 12v ... what are the disks rated at for power up ( spinup ) vs ambeint normal operation - typically 1A to power up and 0.5A for normal spinning operation for a powersupply rated at 12V for 10A .. you can run 5 disks if you run more disks ... your power supply will die faster and/or your data gets corrupted during power ups when the system and the drives think you're in "normal operation" and enables write while in fact, its is still in its bootup > Also, I would not want to push a power supply to the max rating. It should > be sized 50 watts or more beyond what you need. make that 2x the total wattage needed by the system .. NOT 50W - add up the amps needed on the 3.3V, 5V, 12V - use the MAX needed for operation, which is the power up sequence to get a "random number" of operating current .. Total watts == 12 * 12v(maxcurrent) + 5v * 5v(maxcurrent) 3.3V * 3.3v(maxcurrent) - normal operation usually does NOT need as much current - switched power supplies can output higher current than it is rated at, but it will not be able to sustain that "extra current load" for more than a few seconds before its over-current circuitry kicks in to shut itself down - you will be bouncing up and down in current on each power line till the system is all booted - put a digital storage scope on the 12V and 5V and 3.3V line and an ampmeter on each power line and watch it go bonkers c ya alvin - To unsubscribe from this list: send the line "unsubscribe linux-raid" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
