Question

You are trying to determine the appropriate level of high availability for a server. The server must be available on a constant basis, and downtime in a given year cannot exceed 1 hour. It normally takes you about 45 minutes to bring down and restart the server for maintenance. Which of the following reflects the level of availability you require?

A. 99.999 percent availability
B. 99.9 percent availability
C. 99.99 percent availability
D. 99 percent availability

Answer 1

C. 99.99 percent availability

Step-by-step explanation:

The downtime should be between 45 minutes and 1 hour. Because the server needs at least 45 minutes to be up again after maintenance. On the other hand there is a restriction that downtime in a year cannot exceed 1 hour.

• One year has 365 ×24 × 60 = 525600 minutes.

• 99.99% availability means (100% - 99.99%) × 525600 = 52.56 minutes downtime.

• Other availability percentages are either too short (less than 45 min.) or too long (more than 1 hour)