[c-nsp] 6509 power supply question

[Alexandre Snarskii]

On Fri, May 23, 2008 at 11:51:30AM +0100, A.L.M.Buxey at lboro.ac.uk wrote:
> Hi,
> 
> > We running different power supplies on one of our 6509 for years,
> > no problems with that configuration: 
> 
> yes, you just need to be very careful that your blades dont
> draw too much power for the one not in use.  eg if you are currently
> on a 2500W supply...and that fails , leaving you with only
> a 1300W then your blades may take too much for that and thus some
> will fail.

Yes, I should note that this system is old one, Sup2 based, 
with old fans, using only 584.22 Watts, so even when we lose 
AC power - 1300Watt DC power supply provides enough power to run.

> eg in the scenario posted...
> 
> > Switch#show power
> > system power redundancy mode = redundant
> > system power total =     2331.00 Watts (55.50 Amps @ 42V)
> > system power used =       584.22 Watts (13.91 Amps @ 42V)
> > system power available = 1746.78 Watts (41.59 Amps @ 42V)
> 
> so, system thinks its got 1746 available.... and 2331 supplied..
> however:
> 
> > PS   Type               Watts   A @42V Status Status State
> > ---- ------------------ ------- ------ ------ ------ -----
> > 1    WS-CDC-1300W       1153.32 27.46  OK     OK     on 
> > 2    WS-CAC-2500W       2331.00 55.50  OK     OK     on 
> 
> that 1300W wont provide enough if the power used was eg 1341.55 Watts
> as the system THINKS its got 2500....