Re: 165 Halsey recurring power issues

[Sean Donelan <sean () donelan com>]

165 Halsey (and most of its tenant) data centers is an older facility. 
Data center practices have changed over the decades, and terminlogy wasn't 
standardized until recently.


The biggest FUBAR in telco and data centers is the difference between 
"redundancy" and "diversity."

Redundant A/B power feeds are often multiple cables from the same power 
source.

Diverse A/B power feeds are cables from different backup power sources 
(within limits).  1-utility, 2 battery strings or backup generators. 
Often routed through in same conduits/cable trays. But both may be out of 
service for scheduled maintenance and some kinds of faults.

Add a spare A/B power feed.  Generally a N+1 backup power source and some 
additional power switching capability.

Fault tolerant A/B power.  Everything from utility to rack is diverse and 
redudant (cables, conduit/cable trays, switching equipment and backup 
sources).  Maintenance can be performed on one of the power feeds without 
affecting the other feeds.  Does not include redundant utility feed (not 
redundant substation, utility).

Cost increase 2x, 5x, 10x

I haven't toured 165 Halsey for 10+ years, so I don't know its current 
state.  It has multiple tenant data centers, so some may be better than 
others.


On Mon, 23 Oct 2023, Babak Pasdar wrote:
> Hello,
>
> I wanted to get some feedback as to what is considered standard A/B power 
> setup when data centers sell redundant power.  It has always been my 
> understanding that A/B power means individually unique and preferably 
> alternate path connections to disparate UPS units.
>
> A few months ago, 165 Halsey took us down for several hours. They claimed 
> that a UPS failed causing this issue.  Our natural reaction was that we have 
> A/B redundant power so a failed UPS on the A circuit should not take down the 
> cabinet. Joe the facility manager claimed that industry standard A/B power 
> means two circuits to the same UPS, which makes no sense to me.
>
> They committed to move us to A/B power with redundant circuits to disparate 
> UPS units.  However, we had a multi-hour outage again in that site this 
> weekend. At first glance it seems to be the same problem.
>
> We have checked with all of our other data center providers who have 
> confirmed A/B power is in fact individually unique connections to disparate 
> UPS units. 165 Halsey's definition of what constitutes redundant power seems 
> unique. Why would anyone pay extra for a second connection to the same UPS?  
> However, I wanted to get feedback to see if I am taking crazy pills here 🙂
>
> None-the-less, we have lost all confidence in this facility.
>
> Best Regards,
>
> Babak