HP9000 (L2000/L3000) harware question abaut fuse

[MQ'ski]

As I know both servers have 3 line power suply,
Question is abaut fuse specification?
Do you know what fuse should be apply?
M
16A or ?

[Ravi_8]

Hi,

all my L class servers are on 5Amps

[Brian M Rawlings]

Marcin: this is a slightly tricky question, so bear with me.

In a standard HP rack, with modular PDUs, you would ideally plug each power supply cord into a different PDU, requiring 3 PDUs. This is the only way to provide HA/redundant power to this box. If that is not possible, you can plug all three into one PDU, or two into one PDU and the third into another... but if the PDU with two cords in it loses power, the box goes down.

In the US, the standard HP PDU is supposed to handle 16A at 200/240V, 60Hz. They have a built-in breaker that is *supposed* to trip at 16 amps. That is probably where you are seeing a 16 amp figure. I don't know what power/Hz is used where you are, I only know about US power, if it matters.

Now, about the tricky part, the power draw of the L-class/RP54xx boxes:

At 200/240V, the max current the box draws is 6.5 amps, which is shared between the power supplies, equally.

This means that you have to size all three supplies (and their PDUs, and the OTHER stuff plugged into those same PDUs) as though each power supply was going to pull HALF of the total amount (3.25A each).

This is not a typo, I will explain. Normally, each P/S will draw one third of the 6.5A total (max draw), for 2.16A (give or take). If one P/S fails, however, the load is still shared equally by the remaining power supplies, and now they (and their supply circuits) must split the total between them (3.25 amps each). If two supplies die, the box should shut down, since one P/S can't (theoretically) supply enough current to run an L-class.

It is important to size power inputs and power supply allocation to provide for the worst-case, 2-P/S power draw, so you don't put too many devices on one PDU. If you max out the PDU during normal operation, you will exceed the 16A maximum if one P/S ever dies, or if one power source ever gets unplugged.

Hope this helps!

Regards, --bmr