Increasing availability

There are two ways to increase the availability:

• increase the MTBF
• decrease the MTTR

If we took the three nines example above and made the MTTR only six minutes (0.1 hours for easy calculations) our availability would now be:

availability = 1000 / (1000 + 0.1)

which is 0.9999, or four nines—ten times better!