This process involves the following key aspects:

Availability requirements: Consolidate the complete list of availability requirements from business and IT stakeholders and establish the availability model. Collect various sources, load volume, and geographies for which availability SLAs are applicable. Special-case scenarios, such as geo-specific variations or web page/transaction-specific variations, also need to be collated by interacting with stakeholders.

The availability SLA can be derived from responses to questions such as:

• What is the maximum time period before which the business is severely impacted?
• What are industry and domain benchmarks for availability?
• What is the business/financial cost for a one minute outage?
• What is the acceptable data loss? This helps us in understanding RPO.
• Are scheduled outages acceptable?
• How much of an outage is tolerable?
• What are end users' availability expectations, based on surveys?
• Are there any analyst recommendations for application availability?

The following is the availability establishment process illustrated:

Establish availability design criteria: Availability design criteria should cover various aspects of availability, such as hardware design, software design, operations process, and so on.

The following are the key design aspects listed:

• Design for failure
• Design for handling downtime and recovery
• Design for business continuity and continuous operations

Availability models: Develop availability models to simulate the real-world use cases. The model should factor in all possible failures and should simulate system performance and throughput in these scenarios. The simulation models should help the governance team establish availability policies.

Infrastructure setup: Availability policies obtained from simulation models are leveraged to create a robust and reliable infrastructure. Similarly, leverage the design criteria in software component design. Essentially, the infrastructure and software design should be architected to satisfy the business needs and SLAs.