Chassis Power Policy "Grid" - Power save state PSU

[alissonnascimento100]

Hi friends,

We have many UCS domains, and in all of them we're using the "Grid" power policy, we take this decision why we have 2 PDUs in our datacenter (two power sources).
We connect PSU1 and PSU3 in source A and PSU2 and PSU4 in source B.
Recently we''ve had a maintenance in source A and four blade server installed on the same chassis came off.
We checked and saw that PSU2 and PSU4 were in power save state in the maintenance moment, but operable!

We have other chassis in the exactly same way and we didn't had any problem in it.
My question is, when we have 2 PDUs, there's some order to group these PSUs in power sources? if yes, why?
When PSU state is "power save", is it working? if other chassis PSUs come down, they "power save" PSUs get work?

Thanks!!

[Kirk J]

Looking at some IOM log output for grid based configurations, I see the following:

Grid : 0
     Active PS : 0
     Spare PS : 1
     Unavailable PS :
     -----------
     -----------
Grid : 1
     Active PS : 2
     Spare PS : 3
     Unavailable PS :
     -----------

For actual numbering this means PSU #1 and #2 are expected to be on the same grid source, and #3 and #4 are expected to be on the same source.

If you have it wired otherwise,, then the UCSM may put wrong PSUs to sleep (Spare), in which event a single Grid impacting event can knock down both active PSUs.

definitions for example below:

PSUs: 1,2,3,4

grids: a,b

+ : PSU fully on

- : PSU source failed

s: PSU in spare/standby mode

Your config:

1   2   3   4
a   b   a   b
+   s   +   s

then you loose grid 'a' power source

1   2   3   4
a   b   a   b
-   s   -   s   <<<2 PSUs lost AC, and 2 PSUs in standby

If you have it wired for grid on 1,2 and 3,4 what should have happened is:

1   2   3   4
a   a   b   b
+   s   +   s
-   -   +   s   <<<2 PSUs lost (grid a), and only 1 PSU originally in standby on b grid
at which point you have at least one PSU fully online, and then it brings the 2nd PSU member of the grid online

1   2   3   4
a   a   b   b

-   -   +   +

Hope this helps,

Kirk...