Availability is defined as which of the following?

Availability is defined as which of the following?

• A. The ability of a system to perform as designed, without failure, in an operational environment, for a stated period of time
• B. The ratio between uptime and total time of a system, usually expressed as a percentage
• C. Near Miss
• D. Service-level agreement

Answer: (B)

Availability measures how often a system is ready to perform its function when needed. It is defined as the ratio of uptime to total time, usually expressed as a percentage. Uptime is the time the system is operating and able to deliver its service, while downtime includes periods when it is unavailable due to failure, maintenance, or standby. This lets you quantify, in a given period, what portion of time the system can actually meet its intended function. The other descriptions point to reliability (ability to operate without failure over a period), a near miss (an incident precursor), or an agreement about service levels, none of which define availability. For example, if a system runs for 99.5 hours in a 100-hour window, its availability is 99.5%.

Availability measures how often a system is ready to perform its function when needed. It is defined as the ratio of uptime to total time, usually expressed as a percentage. Uptime is the time the system is operating and able to deliver its service, while downtime includes periods when it is unavailable due to failure, maintenance, or standby. This lets you quantify, in a given period, what portion of time the system can actually meet its intended function. The other descriptions point to reliability (ability to operate without failure over a period), a near miss (an incident precursor), or an agreement about service levels, none of which define availability. For example, if a system runs for 99.5 hours in a 100-hour window, its availability is 99.5%.