Architecture & practice·Incidents and what happens after
the errors started at 09:02 and the first alert fired at 09:41, and a customer had emailed at 09:12.
Time to detect
Also calledTTD, detection time
How long a failure lasted before anyone knew about it. It is the part of an incident timeline most likely to be embarrassing and most likely to be improvable, since it is a monitoring problem rather than a hard engineering one. A review that only examines what happened after the page is skipping the segment where the cheapest minutes are usually available.