Upgrading Availability

How much should you spend to upgrade your system's availability?

Assuming you already have a networked computer system and that you have computed its availability A, its cost C of downtime per hour, and the number of hours Y in a year that it needs to be fully functional, then its expected annual cost of downtime is M=Y×(1-A)×C. A good rule of thumb is that you can get a three year return on investment if you can spend M dollars upgrading your system to reduce expected downtime by 1/3. We call this The Availability Rule of 3's. This rule of thumb works not only for 7 by 24 systems where Y=8766 but also for other systems with fewer critical hours in the year.

Many businesses can spend far less than M dollars and get an even greater reduction in expected downtime. This is especially true at the low availability ratings. (It is a sad fact of life that it is cheaper to make a poor system into a good one than it is to make a good system into a great system.) The figure to the right illustrates this. Near the bottom the availability improvement per dollar is greatest, and near the top it is the smallest.

Bristol Systems can help you with your upgrade designs and with their associated availability and upgrade cost calculations. Call us at 714.389.4136 to discuss our availability services.