Defining load and redundancy

[Anonymous user]

Hi,

I inherited a previously installed Symmetra Power Array MasterFrame. Impressive piece of technology and I'm glad it's guarding the power for my servers. I have read the documentation a couple of times, but one thing is unclear to me. How do you define the maximum load, or the number N in the N+1 power modules? I know I can potentially get 16KVA out of the chassis, but that is not nearly what I need. How can I define that if I only put 4 power modules in it, that it would still use one as a redundant unit? Do I have to put all potential 5 units in it?

Thanks in advance,

Wouter

[BillP · Accepted solution]

Hello,

Your maximum load would be determined by the load (your servers) plugged into the UPS. 'N' is your power (wattage/volt amps) need determined by you and +1,2,3,or 4 is determined by how many extra power modules you have in there. Each Power Module for the Symmetra Power Array is 4kVA, 2800 watts.

Based on whatever load is being draw and how many power modules are installed, the UPS calculates redundancy for you and you can see load percentage in the status menu and redundancy. So if you have two power modules installed, and lets say 1000 watts of load, you'd have N+1 redundancy since one power module can support the load alone so you have one redundant module.

I hope that helps clarify. Let me know if you have any other questions.

[Anonymous user]

Thanks!

The thing that got me wondering was that I had one failed power module. And the UPS stated that I now had no redundancy. But when I removed the module and took the system out of bypass, it happily re-evaluated the load and declared that I was again in N+1. So before the module failed, I must have been in N+2, but the UPS didn't know or realize this.

Thanks!