[AusNOG] What's Typical Power Density in Colo?

[Julien Goodwin]

On 03/05/12 20:43, jason andrade wrote:
>> Must be N+1 (ala fully redundant power) and have reasonable connectivity.
> 
> Which one did you want ? N+1 or redundant (2N) or fully redundant (2N+2N)..

Ugh, power redundancy.

So there's:

* 1 - Single feed, no redundancy
* N - One or multiple feeds, no dependency
* N+1 - One or multiple feeds, handles any single feed failure
* 2N - One or multiple feeds, handles 50% failure
* N+2 - One or multiple feeds, handles any two feeds failing
* 2N+1 - One or multiple feeds, handles 50% failure, and one more feed
failure

And that's just off the top of my head.

Of course there's all the fun cases where power *feeds* don't equal
power *supplies*, which is the case on some stuff (A bunch of the large
Juniper's just to start). Then there's the whole load-sharing vs.
failover cases (can your breakers actually handle it if you lose a feed,
what about starting your systems from cold)

You always want to be *very* clear what you mean, especially as some kit
can be configured in multiple ways (even in software, eg HP bladesystem).

The traditional telco way to do this was two main building feeds, A and
B, and you order an X amp feed, or an X amp feed A+B if you want redundancy.