Installation manual

Power System Redundancy Overview
The BlackDiamond X series chassis has slots for eight PSUs. There is a power connector on the back for
each PSU. If all populated PSUs are powered from 220VAC, then each PSU is capable of supplying
about 2500W to the chassis. If any PSU is powered by 120VAC, then each PSU is capable of supplying
about 1250W.
Note
2500W and 1250W are approximations. When several PSUs are installed in a system, the
actual power per PSU decreases by up to 10%. This decrease is taken into account when a
system is configured.
N+1 Redundancy
To guarantee that the BlackDiamond X series will operate properly in the event of a single PSU failure,
the user must calculate how many PSUs are required to power all the modules and fan trays in the
configuration.
Do the following to calculate the number of PSUs required for N+1 redundancy:
1 Add up the power consumptions of all the MMs, IOBs, FMs, and Fan Trays in the system.
2 Divide the total power consumption by either 2500 or 1250 (depending on line voltage), and round
the result up to the next whole integer (this number is ‘N’).
3 Add 1 to N to get the total number of PSUs required for N+1 Redundancy.
If more modules are added to the chassis, more PSUs may be needed to maintain N+1 Redundancy. N+1
Redundancy is possible with any existing chassis configuration, even if the line voltage is 120VAC.
N+N Redundancy
N+N refers to power source redundancy. For instance, a data center may have two independent power
sources available so that if one source fails, the other source (backup) will automatically take over and
power the BlackDiamond X series chassis.
To achieve N+N redundancy, the top row of PSUs (Bank A) should be powered from the same facility
power source, (that is, plugged into power circuits derived from a single power source). The bottom
row of PSUs (Bank B) should be powered from the backup power source. The user needs to install
enough PSUs in each bank to power the entire BlackDiamond X series chassis. If the line voltage is
220VAC, then there should be no problem powering the entire chassis with four PSUs. If the line
voltage is 120VAC, most configurations can be powered by four PSUs.
Simultaneous N+1 and N+N Redundancy
To achieve both N+1 and N+N redundancy at the same time, three (or fewer) PSUs must be capable of
powering the entire BlackDiamond X series chassis. Each bank of PSUs should be populated with
enough PSUs to power the chassis (N) plus one more chassis (N+1).
Understanding Power Supplies
BlackDiamond X Series Switches Hardware Installation Manual 30