Availability in Cloud Computing

Availability in Cloud Computing is quite well hear terminology ! We often read High Availability Cloud, we read the percentages of probable Availability. So let us see what this terminology Availability actually means.

Availability in Cloud Computing and Other Terminologies in Computing

These terminologies are not actually specific for Cloud Computing, rather they are for computing and can be expressed mathematically. The availability of a technical system is the probability or the extent that the system meets certain requirements to or within an agreed time-frame. It is a quality criterion and a measure of a system.

Since in the calculation of availability only the downtime is expected within the agreed period, there is a scheduled downtime (eg, to perform maintenance tasks) outside the agreed period. Only one occurring unplanned downtime is counted as downtime. If a full 7 × 24 availability is agreed, it means that there is no planned downtime. Any interruption of service is then counted as downtime. Servicing to such systems – as far as possible – must be executed during its  operation.

Availability in More Details

In case Cloud Computing or server the availability is measured as period of uptime per unit of time and expressed as a percentage. Availability is also no longer given if the response time of a system exceeds a certain character. It is expressed as unit of time, typically in minutes, hours, days, months, quarters or years used. Availability as a property of a system is therefore in the contract or SLA.

Indicators of availability are :

• Maximum duration of a single failure
• Reliability
• System and data integrity
• Maintainability
• Response time
• Mean Time to Repair
• Mean Time Between Failure
• Mean Time to Failure

Conceptually, we use High Availability Cloud to indicate a different redundant system, which is structurally different than usual platforms.