IMPACT OF SOFTWARE FAILURES ON THE RELIABILITY OF A MAN-COMPUTER SYSTEM

摘要

Software failures and human errors are the most common reasons of inoparability of computer systems. Computers are increasingly reliable, but the level of transcient faults, caused by errors hidden in the programs, remains the same. For this reason software is becoming the key factor in the synthesis of highly reliable systems. Software errors do not result from operation, they either exist from the start or are inserted when patching or upgrading it. Some errors result from incorrect human interaction or unexpected environmental changes. Assessment of software impact requires functional-reliability approach to reliability analysis: the software fault occurs when it causes incorrect operation and not when it is introduced to the system. It is proposed to use software reliability models in system analysis, to predict the intensity of software faults. The software recovery after a failure is realized by restarts of various extend (microrestarts, minirestarts and macrorestarts). The impact of software failures and restarts on system availability is assessed.