Explain like I'm five · Security

What is Disaster Recovery?

Disaster recovery and business continuity, told as a story about the plan that opens the market the morning after the castle burns, floods, or gets locked up.

the thief's lockwhat about tomorrow's market?guests are waitingflood, fire, thief — one day the castle stops

Flood, fire, thief. One day the castle stops.Sometimes it's fire, sometimes water, sometimes a thief's lock on every chest. And the guests still come tomorrow.

the spare chest is thereopen it where?who does what?how long will it take?there's a chest, but no planthe spare chest is the start, not the end

The spare chest is there. But where, who, and how fast?The spare chest far away is the start, not the end. Nobody knows where to open it, who opens it, or how long it takes.

IF THE CASTLE STOPS1WHERE — the hall in the next village2WHO — captain: doors, clerk: ledgers3HOW FAST — by morning4HOW MUCH LOST — a day's worth at mostthe spare hall — our other castlewrite the plan before the dayeven if the castle burns, tomorrow morning the market opens

Disaster recovery is the plan, written in advance, for where, who, and how fast we reopen when the castle stops.Where to reopen (the other castle), who does what, how fast it must open, and how much we can afford to lose. Four things, decided ahead.

Where — the other castlethe hall next village
Who does whatcaptain: doors, clerk: ledgers
How fast, how much lostby morning, a day at most
Practicea pretend fire every spring
morninghow fast we reopenby morning — within that timelast night's copythis morning's pages are gonehow much we can losea day's worth — no morethe king sets both — faster and less both cost more

How fast and how much lost are two different numbers.If we said by morning, it has to open by morning. With only last night's copy, this morning's pages are lost — that's a day's worth. Faster and less both cost more. The king decides.

springpretend firerun through the plannext morning, open for businessa plan never rehearsed can't be read in front of a fireplan + spare chest + practice = tomorrow's market

Every spring, a pretend fire to practice. That's how the market opens the next morning.A plan never rehearsed can't be read in front of a fire. It pairs with the order of things when a thief gets in — that one gets the thief out; this one gets the market open.

In one breath

Disaster recovery = the rehearsed plan for where, who, and how fast we reopen when the castle stops, and how much we can lose. A spare chest alone isn't enough.

DR is the plan to bring systems back after a disaster; BCP is the plan to keep the business running meanwhile. Set the recovery time objective (RTO) and recovery point objective (RPO), prepare an alternate site and roles, and prove it with regular drills.

When grown-ups say it

BCP (Business Continuity Plan)
How the market opens tomorrow. Everything that keeps serving guests when the castle stops — not just chests, but people, places, and order.
DR (Disaster Recovery)
The plan that rebuilds the castle. Taking out the spare chest and reopening, where and how. One part of the continuity plan.
RTO (Recovery Time Objective)
How fast. By morning. The time allowed between stopping and reopening.
RPO (Recovery Point Objective)
How much lost. A day's worth at most. What may be lost since the last copy. More frequent copies make it smaller. → the spare chest
Alternate site (hot / warm / cold)
The hall next village. A hall lit and stocked (hot), a building where chests must be carried in (warm), an empty lot (cold). Faster costs more.
DR drill / tabletop exercise
A pretend fire every spring. Actually run the plan. Sometimes it's done at a table, in words only.
Backup
The spare chest. Where the plan starts. No chest, nothing to open. → the spare chest far away
Incident response
The plan for when a thief gets in. That one gets the thief out; this one gets the market open. → the order of things when a thief gets in
Next story
The Builder and the Guard, Side by Side →
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