Disaster

A catastrophic event that results in long downtime (days or even weeks). Examples:

• War
• Fire
• Floods
• Power grid disruption

Typically this results in loss of infrastructure and data.

When designing a system to survive a Disaster it is assumed that only one Disaster takes place at any point in time. I.e.: one can plan for a Region to go down, but one does not also take measure to handle the scenario where the backup region also goes down.

If a Failure is a flat tire, then a Disaster is running the car into a brick wall where both the car and everything in it is permanently lost.

The measures to make systems resistant to a Disaster are vastly different from measures to make a system resistant to Failure. For that reason it is advisable to distinguish between the two when determining Non-Functional Requirements.

Related terms: Failure