norco 4224: reality caught up to me

[tmp31416]

finally building my new server to replace my old one.

 

inexplicably, a norco 4224 was cheaper to buy than a 4220 by ~120cad, so i went with that.

(btw, the backplanes are rev 2.0, are those safe with 3tb green drives? my 2 parity drives will be 4tb -- thinking ahead to unraid 6.2 here)

 

i got a 850w psu (EVGA SuperNOVA 850 B2) to make sure there would be enough power.

 

anyway, "reality" is that i ran out of power cables/connectors (didn't quite have that issue with my 1st server) and am leery of using splitters, or even using more than one power connector per power cable (i.e., powering more than one back plane with only one power cable).

 

i researched every other component to ensure mutual compatibility (esp. with unraid!) and to ensure maximum bandwidth (chose my motherboard because its two pcie x16 slots are both x16) but forgot to pay attention to the number of power cables that would be required. *major facepalm here*

 

two back planes are powered by the two "perif" connectors on the psu ("perif1" & "perif2") and will have to use sata to molex converters to power three more backplanes from the "sata1", "sata2" & "sata3" connectors on the psu.  the only power connectors slots left on said psu are for "vga" and "cpu".

 

besides wanting to power the last backplane, if at all possible, i also need to power the 5 noctua fans in the case (3x120mm + 2x80mm). well, i already have 1 of the 80mm connected to the motherboard's single chassis fan lead.

 

does anyone have a suggestion/advice on how i could get out of this sticky situation?

 

thanks in advance,

 

p.s.: (edit) one possible solution might be to change my psu to one with more molex connectors on it, but i'm trying to see if there is an inexpensive solution to my quandary. i find it hard to accept that my 850w psu would be inadequate.

[MyKroFt]

You only need to use 1 of the 2 molex connectors for each backplane.  I read somewhere here on the forums that powering both from the same power supply can ether toast the backplane and/or hard drives.  I only use 1 connector per backplane since I do not use dual power supplies

 

Myk

 

[tmp31416]

@Mykroft:

 

each "v2.0" backplane has only one molex connector.

can't check right now, but are you also using a 4224?

how did you arrange power in your server?

 

cheers.

 

*edit* i now see you use a 4220.  still curious how you arranged power.

*edit2* corrected misspelling of your userid. mea culpa!

 

[uldise]

@Mykroft:

 

each "v2.0" backplane has only one molex connector.

can't check right now, but are you also using a 4224?

how did you arrange power in your server?

 

cheers.

 

*edit* i now see you use a 4220.  still curious how you arranged power.

*edit2* corrected misspelling of your userid. mea culpa!

 

I have about 3 years old Norco4224, and each backplane have 2 Molex - its for redundant power supply as mentioned already.

i'm using seasonic PSU, so i'm wondering about your problem with cables - mine comes with 1to3 Molex cables - so for all 6 backplanes i need 2 wires connected to PSU.

[ohlwiler]

I recommend at a minimum three wires going to the backplanes (eight drives on each). You can probably get extra cables from EVGA. If not, time to break out the soldering iron. I modifed the cabling on both of my power supplies to minimize the number of drives on each wire bundle from the power supply.

[HellDiverUK]

If you're running "normal" drives like WD Reds or the like, they only draw 5W each, and maybe 15W at spin up.  That's a peak of 60W per backplane at worst.  Absolutely no issue for one molex.  You could populate the whole machine with drives and run a quality 300W PSU with no issues.

[JonathanM]

If you're running "normal" drives like WD Reds or the like, they only draw 5W each, and maybe 15W at spin up.  That's a peak of 60W per backplane at worst.  Absolutely no issue for one molex.  You could populate the whole machine with drives and run a quality 300W PSU with no issues.

That math doesn't sound right to me. Are you sure you aren't confusing watts with amps?

[Squid]

If you're running "normal" drives like WD Reds or the like, they only draw 5W each, and maybe 15W at spin up.  That's a peak of 60W per backplane at worst.  Absolutely no issue for one molex.  You could populate the whole machine with drives and run a quality 300W PSU with no issues.

WD Reds have a peak current rating of 1.75A (according to WD) which is 21Watts.  21Watts x 24 drives = 504Watts.  Even assuming your 15Watts, 24 drives would draw 360Watts which is still over your "quality 300W PSU"

 

But, making a purchase decision based upon wattage of the drives and wattage of the power supply is a recipe for disaster, as you are ignoring the fact that the wattage of a power supply includes the +5V, +3.3V, +5Vsb, and -12V rails.

 

The way to do it is to look at the peak amperage of the drives (12v), add them all up, and then compare it to the amperage ratings of the 12v rail on the supply.  (On single rail supplies you will also add a couple of amps for the motherboard / additional cards.  The 5V / -12V / 3.3V ratings can be safely ignored on everything but the absolute cheapest power supplies available - and why would you use one anyways?)

 

Additionally, you also have to consider the fact that power supplies all lose capacity over time regardless of the quality of them.  IE: The 300W power supply that you bought a year ago is not able to supply the same capacity now that it did when it was new.  You've got to always add in aging factors to any supply.

 

To make matters worse, a smaller capacity supply will also have fewer feeds coming from the supply.  Your typical 300Watt supply would only have a single peripheral feed (molex and/or sata) at say 18 or 16 gauge.  16 Gauge wire is rated to carry 22 Amps.  (18 can do 16 amps - and odds on a 300W supply will have 18ga wire)  So now you're trying to pull up to 1.75A x 24 drives = 42 amps through a wire rated to do up to 16 amps.  Not a good scenario.  Even if the supply had two feeds coming from it for peripherals you're going to wind up drawing 21 amps on each of them.

[TUMS]

I run 2 backplanes per-lead on mine no problem.  Corsair HX-750w with mostly reds installed.

[Squid]

I run 2 backplanes per-lead on mine no problem.  Corsair HX-750w with mostly reds installed.

1.75A x 8 drives = 14A... No problems...

[tmp31416]

i am using wd green drives, not reds, as the latter are much more expensive than greens.  i could progressively replace the greens with reds later on, though i never had any issues with greens in my existing box.

 

so am i wrong to understand that i should be able to plug in two backplanes per "sata" power cable coming out of my psu?

each "sata" cable has 4 sata power connectors on them (save one with 3 connectors only -- see photo below), so the power draw for two backplanes is not too much for

just one cable?

 

 

i hope that my rev. of the 4224 backplane should permit that -- see photos below.

 

 

can one assume that sata-to-molex adapters, like the one pictured below, are ok?  it's annoying that manufacturers can't be bothered to include such adapters in the psu packaging or can't provide more cables with molex connectors on them (turns out the "perif" cables that came with my psu don't have the same wire count as the "sata" ones. it would not have been a good idea to use them to power the backplanes).

 

 

thanks all for the feedback.

i guess i was getting too pessimistic / paranoid for my own good... 

 

[TUMS]

OP, to answer your question you should have no worries hooking 2 backplanes per cable.  You could probably get away with more to be honest, especially since you're only running green drives, but i'd stick with 2 per cable and you should be good.