HDD Amperes requirements

[Ralph_McCloud]

Howdy,

as I am planning on installing some more HDDs in my server, I would appreciate if any of you could answer me the following questions:

1. As I couldn't find anything regarding the +5V spinup requirements of the Samsung HD154UI drives in terms of the Amperes, how many HDDs could I, on average, connect to a PSU with 28A on the +5V line (or would the +12V Amps be the limiting factor here?)?

2. Given the scenario that a PSU got 4 rails with 22A each, what happens when I connect devices which would require 28A to start up to one of said rails?

Server Specs:
Intel C2Duo 6420
4x1GB DDR2 800MHz RAM
ATi HD4850
TV Card + 2 S-ATA Controller Cards

Thanks in advance

 

[blivit4]

You can take a look here:

http://www.xbitlabs.com/articles/storage/display/1tb-hdd-roundup-3_18.html#sect0

 

[Ralph_McCloud]

Thanks for the link, blivit4.

So I guess with 0.8A spinup the max HDD-count would be around 25 if one considers that other components also require some Amps on the +5V line.

I suppose I will have to go with a controller supporting staggered spinup then to avoid running into such issues.

 

[Zero82z]

The drive motors are powered from the +12V rail. +5V is used for the controller board.