When I talk about disaster recovery, one of the key things that I try to stress is the idea that the amount of effort and resources you devote to the problem is often scaled to the risk of loss. It doesn't help the company if you decide to spend $1mm to ensure extremely high availability and zero data loss for a system that generates $20k in revenue a year. It also isn't worth spending $100k to protect a system from more than a day of downtime if your daily revenue is less than $5,000.

However when we talk about disaster recovery is seems that the vast majority of people plan for a data center failure, or a hurricane, or a major disaster. Those are possibilities, but the risk of them happening is low. It's rare that a major disaster will hit any particular part of the world and therefore the risk is often very low. With a low risk, it might not be worth spending a lot of money on extra hardware to handle a situation that may never occur. I know that most of the time the management I've worked for haven't felt it was worth spending a lot of money to prepare for a major disaster. There are systems that are worth duplicating to ensure high availability, and in many cases it does seem that management is willing to pay for spare systems when downtime is an issue.

Read the rest of "Probabilities and Disaster Recovery" at SQLServerCentral.