[j-nsp] Power failure - unexpected?

[sthaug at nethelp.no]

>   we´ve got an M320 with 4 power modules, a single routing engine and 
> the following FPC´s:
> 
> 1 FPC type 1 (with 2xGigE)
> 1 FPC type 2 (with 3xOC-48)
> 1 FPC type 3 (with 2x10GE)
> 
> During a maintenance, we had to turn off only 2 power modules, but 
> unfortunately the whole box went down ...
> 
> According to docs, I was expecting the router to stay up and running, 
> once this is not a fully "loaded" router (without lots of FPC type 3, 
> for instance).
> 
> What went wrong ? ;)
> 
> Are there circumstances where I can turn off 2 power modules and M320 
> stay running?

It depends on type of power module (AC or DC) and *which* modules you
remove. An M320 can operate with two out of four DC power supplies (we
have verified this):

http://www.juniper.net/techpubs/hardware/m320/fru-m320-dc-power-supply.pdf

and from what I can see, it can also operate with two out of four AC
power supplies:

http://www.juniper.net/techpubs/hardware/m320/m320-ac-power-supply-fru/m320-ac-power-supply-fru.pdf

Steinar Haug, Nethelp consulting, sthaug at nethelp.no