January 26, 201115 yr Would this APC UPS be able to support the 4224 Norco with all bays full? http://www.tigerdirect.com/applications/SearchTools/item-details.asp?EdpNo=3612224 If not, what would be the recommend APC UPS for this server that has a 750w PSU? Thanks..
January 26, 201115 yr It may work, but it is a 540 watt UPS. It could not handle 750 watts of load. (but I doubt your full server draws anywhere near 750 watts) From the spec-sheet at the link you gave... Watts: 540 Watt Full Load Run Time: 5.5 Minutes
January 26, 201115 yr Author Thanks Joe L. That's fine. As long as that's time enough for a graceful shutdown, I'm good.
January 26, 201115 yr I believe unRAID spins up all the disks prior to shutdown. If all disks are sleeping when the power goes out, then the power draw on the 12 volt line will be about: 12 volts *(2 amps per drive * 24 drives + 5 amps (other)) = 636 watts. Assume 80 percent efficiency on the power supply, and a power factor of 1 = 795 watts. It may work, but you are drawing more power than it is rated for. I would shoot for a 800 - 1000 watts rating.
January 26, 201115 yr but I doubt your full server draws anywhere near 750 watts looks like I was wrong... as the math shows..., when spinning up 24 drives a fully loaded server may draw more than 750 watts. The UPS is probably too small.
January 27, 201115 yr In my 4224 using an 800 watt power supply, running 23 drives, 21 are green, and I leave my drives spinning up all the time I'm consistently around 240 watts. Would this UPS not work since I've already got everything spinning or am I missing something? thanks Josh
January 27, 201115 yr In my 4224 using an 800 watt power supply, running 23 drives, 21 are green, and I leave my drives spinning up all the time I'm consistently around 240 watts. Would this UPS not work since I've already got everything spinning or am I missing something? thanks Josh The problem is the instantaneous spikes that are generated when the server brings up all the drives at the same time. Even if you don't have your drives set to spin down, you still get large peaks when you apply power to the server on a cold boot. If you look at the power readings I took on my rig I got a 120W spike on power on, but only half that at idle. Even doing a parity check (which I don't have measurements for) the current used would not push the power consumption to that level. Based on ohlwiler's math, you are probably ok even if you are at the low end of the acceptable range. But I take no responsibility if things explode on you
January 27, 201115 yr In my 4224 using an 800 watt power supply, running 23 drives, 21 are green, and I leave my drives spinning up all the time I'm consistently around 240 watts. Would this UPS not work since I've already got everything spinning or am I missing something? thanks Josh If you leave all the drives spinning all the time, then yes, it will probably work.
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