Availability Testing

Definition

Availability testing is the the system testing of an integrated, blackbox application against its operational availability requirements.

The typical goals of availability testing are to:

Cause the operational availability of the application to fail to meet its requirements so that the underlying defects can be identified, analyzed, fixed, and prevented in the future.

The typical objectives of availability testing are to:

Determine:
- If the application meets its operational availability requirements. (For example, availability testing can cause failures due to memory leaks or database indexing defects.)
- How stable the application is.
- Whether (and how much) downtime is required for maintenance purposes.
Report this information to the development teams so that any associated defects can be fixed.
Provide information that will assist in the optimization of operational availability.

Typical examples include availability testing of an application that is:

Availability test execution can typically begin when the following preconditions hold:

The operational availability requirements to be tested have been specified and fully implemented.
The relevant software components have passed unit testing.
Software integration testing has started. However, operational availability testing can begin prior to the distribution of the software components onto the hardware components.
The relevant system components have passed system integration testing.
The independent test team is adequately staffed and trained in availability testing.
The test environment is ready.

Availability testing is typically complete when the following postconditions hold:

At least one test case exists for each operational availability requirement.
The test suites for every scheduled operational availability requirement execute successfully.

Availability testing involves involves the independent test team performing the following testing tasks:

Availability testing is typically performed on the following environments using the following tools:

Availability testing typically results in the production of all or part of the following work products from the test work product set:

Availability testing consists of the following tasks being performed during the following phases:

PHASE → TASK ↓	Business Strategy (*)	Business Optimization	Initiation	Construction	Delivery	Usage	Retirement
Test Planning	Not Applicable	Not Applicable	Completed	Optional Regression	Not Applicable	Not Applicable	Not Applicable
Test Reuse	Not Applicable	Not Applicable	Optionally Started (**)	Completed	Not Applicable	Not Applicable	Not Applicable
Test Design	Not Applicable	Not Applicable	Optionally Started (**)	Completed	Not Applicable	Optional Regression	Not Applicable
Test Implementation	Not Applicable	Not Applicable	Optionally Started (**)	Completed	Not Applicable	Optional Regression	Not Applicable
Test Execution	Not Applicable	Not Applicable	Optionally Started (**)	Completed	Not Applicable	Optional Regression	Not Applicable
Test Reporting	Not Applicable	Not Applicable	Not Applicable	Completed	Not Applicable	Optional Regression	Not Applicable

(*) Optional availability testing of COTS software components during the technology analysis and technology vendor selection tasks.
(**) Optional availability testing of the executable architecture as well as the COTS components during the vendor and tool evaluation and vendor and tool selection tasks.

Some systems require high availability, which only allows a miniscule amount of downtime. Other systems require continuous availability, which does not allow for any scheduled downtime; the system must be available for users even while it's hardware is replaced or its software is upgraded.
Perform the following:
- Place hardware temporarily offline. Because these updates would be performed during a time of low traffic in a real-world environment, it is acceptable if the system handles a smaller load during the test. Nevertheless, all of the user requests have to be fulfilled.
- Upgrade a software component.
- Perform availability testing for several days.