165 Halsey recurring power issues

Mon Oct 23 22:05:49 UTC 2023

On Mon, Oct 23, 2023 at 7:38 AM Babak Pasdar <babak at pasdar.com> wrote:
> 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.

If they're being truthful (and many folks are not) then A/B power
means that your power is redundant back to at least two different
UPSes. The UPSes are maintained at under 40% capacity so that a
failure of one doesn't cascade to the other. Ideally these UPSes back
to two different generators, also maintained at 40% of capacity. In
large, fancy data centers they even get power company feeds from two
different substations.

Don't just ask the sales droid. When they deliver the rack or the
cage, ask the data center manager to show you where your power
connections run. If they can't or won't... don't believe them.

"Industry standard" A/B power does NOT mean two circuits to the same
UPS. That's just extra power, not A/B. Joe lied to you.

Incidentally, if you're worried about N+1 redundancy, I assume you're
hosted at more than one data center from more than one vendor?
Buildings and vendors are single points of failure too. Even when
built right, stuff happens.

Regards,
Bill Herrin

-- 
William Herrin
bill at herrin.us
https://bill.herrin.us/