What is availability?

Actually, a simple question but the answer is very complex. So, in turn, look into the following approaches.

First approach

Availability is the ratio of time within an agreed period in which the system is operational for its actual purpose (operation time) at the agreed time.

The operating time may be limited by:

• Planned maintenance
• Unplanned maintenance
• Error
• Damage
• Repair time to eliminate errors and damage

The measure of availability is usually given as a percentage.

Second approach

Alternatively, availability is also defined as the proportion...