It wasn't until I turned on the radio that I realized the extent of the damage. Parts of the Northeastern United States and Canada had been knocked out. Far from the normal half hour interruption, it lasted several days. For some companies it was a real disaster.
How long can your business go without power? If you lost all of your computer systems right now, what would you do? If a fire ripped through your files, how would you recover? As my client found out there comes a time when the disaster plan is no longer a theoretical exercise.
Identify which systems are critical and which are not. Often accounting is not that critical. Things can wait a few days while you get a new computer set up. One client had a simple plan for his payroll system, just instruct the bank to pay the same thing as last month until the system was back up. There are lots of resources on the web to help you, for example go here.
Sometimes it pays just to ask your staff those what-if questions, e.g. what if the accounting system goes down? One of my clients was spitting mad. He had gone on vacation for a week and the head office computer system had been down for two days. Without the order entry system, his customer orders didn't get sent into the back for production. He lost two whole days. "The system may have been down, but the photocopier still worked. Why didn't they just slap a shop order number onto a copy of the customer purchase order and send it into the back?" he fumed. But he knew the answer: because nobody had thought about what to do when disaster strikes.