Write a summary of the incident in a few sentences, including
Why it happened
The severity of the incident
How long the impact lasted
Key Performance Indicators
Time to Repair
Time form the incident started until normal operation is restored
Time to Recover
Time from the incident started until it is resolved
Time to Respond
Time from incident was discovered until normal operation was restored
Time to Acknowledge
Time from first indication of the incident until work was started to resolve it
Time Since Last Failure
Time from the end of previous incident to start of this one
Describe the sequence of events that led to the incident, for example
Previous changes that introduced bugs that had not yet been detected
Describe how the change that was implemented didn’t work as expected. If available, attach screenshots of relevant data visualisations that illustrate the fault.
Describe how the incident impacted internal and external users during the incident. Include how many support cases were raised.
How many users were affected
For how long time
What was the severity of the impact
When did the team detect the incident? How did they know it was happening? How could we improve time-to-detection?
Consider: How could we cut that time by half?
Who responded to the incident? When did they respond and what did they do? Note any delays or obstacles to responding.
Describe how the service was restored and the incident was deemed over. Detail how the service was successfully restored and how you know what steps you needed to take for recovery
Depending on the scenario, consider these questions
How could you improve time to mitigation?
How could you have cut that time in half?
Detail the incident timeline
Include any notable lead-up events, any starts of activity, the first known impact and escalations. Note any decisions or changes made, and when the incident ended, along with any post-impact events of note.
Root Cause Analysis
The five why's is a root cause identification technique. Here’s how you can use it
Begin with a description of the impact and ask why it occurred
Note the impact that it had
Ask why this happened, and why it had the resulting impact
Then continue asking “why” until you arrive at a root cause
List the “why's” in your postmortem documentation
Review your engineering backlog to find out if there was any unplanned work there that could have prevented this incident, or at least reduced its impact?
A cleared-eyed assessment of the backlog can shed light on past decisions around priority and risk.
Now that you know the root cause, can you look back and see any other incidents that could have the same root cause? If yes, note what mitigation was attempted in those incidents and ask why this incident occurred again.
Discuss what went well in the incident response, what could have been improved, and where there are opportunities for improvement.
Describe the corrective action ordered to prevent this class of incidents in the future. Note who is responsible and when they have to complete the work and where that work is being tracked.