Related characteristics
maturity
fault tolerance
recoverability
availability
degradability
Recoverability
Description
Attributes of software that bear on the capability to re-establish its level of performance and recover the data directly affected in case of a failure and on the time and effort needed for it.
Indicators
1. mean time to repair (MTTR)
Average time needed to recover the damaged software product.
Source: QUINT
Scale: ratio
Validity: ***
Protocol:
1. During a certain period of time, measure the duration of the periods in which the software product is out of order;
2. Average the duration of these periods.
or, Protocol:
1. During system-testing, measure the duration of the periods in which the software product is out of order;
2. Average the duration of these periods. Note: recoverability also depends on organisational and hardware aspects.
2. auto recovery ratio
The ratio of automatically resolved failures (by the software product) to the total number of failures for which automatic recovery would be preferred.
Source: QUINT
Scale: ratio
Validity: ***
Protocol:
1. Determine the failures and estimate the possibility of these occurring;
2. Develop tests for these failures;
3. Determine which ratio of failures are automatically resolved by the software product.
Note: In general, failures external to the software product have to be simulated by the system software.
3. mean recovery time
The mean time between occurrence of software system breakdown and completion of recovery from breakdown.
Source: ISO
Note: This indicator corresponds with (1) Mean Time To Repair.
4. mean breakdown time
The mean time between occurrence of software system breakdown and completion of recovery and restart from breakdown.
Source: ISO
5. mean restart time
The mean time between completing recovery of software system breakdown and completing restart after breakdown.
Source: ISO
6. mean fault life
The mean time between introduction of a fault and removal of the fault.
Source: ISO