Explain like I'm five · SRE

What is a Game Day?

Game day, told as a story about picking a day and practicing a pretend breakdown together.

broken!who do I even call?!I've never seen this screen before?when the real thing hits, everyone fumbles like it's their first time

When the real thing hits, everyone fumbles like it's their first time.Even with the pager in hand, it's not clear who to call.

FIRST RESPONSE LOG20 min just to reach someone10 min not naming a commanderwhere's the manual?doing it for the first time means slow and wrongif you've never practiced, doing it for the first time during a real incident is too slow

If you've never practiced, doing it for the first time during a real incident is too slow.20 minutes just to reach someone, another 10 deciding who's in charge.

CALENDARMON TUE WED THUFRI: DRILL DAY!and next month too(drill) brokenpick a day and practice together, just like the real thingalright, let's pretend ride A just broke!

Pick a day and practice together, just like the real thing.The pager rings for real, and someone is named commander.

Pick a date ahead of timemark it on the calendar
Decide the scenariowhat's pretending to break
Ring the pagers for realand name a commander
Afterward, record what was slowso next time is faster
DRILL NOTICE (internal)this Fridayassume ride A breaksguests won't knowmark the drill day on the calendar and practice together while guests don't even notice

Mark the drill day on the calendar and practice together while guests don't even notice.Guests don't need to know it's a drill at all.

TOO OFTENdrilling every weekeveryone gets exhaustedTOO RARELYonce a yeareveryone forgets the drilltoo often exhausts everyone, too rarely loses the effect — you need the right rhythm

Too often exhausts everyone, too rarely loses the effect.Finding the right rhythm matters.

In one breath

Game day = a scheduled day when the whole team practices a pretend breakdown, as realistically as possible, and afterward records what was slow.

A drill that triggers a simulated incident under a planned scenario and rehearses the real response procedures — paging, command, communication — exactly as they'd happen. It can be seen as chaos engineering done on a regular schedule, as a whole team. Too frequent and fatigue builds up; too rare and skills fade, so getting the cadence right matters.

When grown-ups say it

Game day
A scheduled drill the whole team does together. Just like the real thing, but with no real damage.
Disaster-recovery drill
Another name for the fake fire-drill day. Practiced on a set day with a set scenario. → the people who keep the park open
Scenario design
Deciding in advance what's pretending to break. Too easy teaches nothing; too hard and someone gets hurt.
Role rehearsal
Trying on the commander, mechanic, and operator roles ahead of time. So no one's confused about who does what in a real incident.
Relation to chaos engineering
The fake breakdown itself. A game day is doing this on a regular schedule, together. → the fake breakdowns caused on purpose
Recording the lessons
Writing down afterward what was slow. The next drill gets better because of it.
Measuring recovery time
Timing how long the drill took. You need the number to know if you've improved.
Runbook check
Checking during the drill whether the mechanic's notebook is still accurate. Update the notebook every time you drill.
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