On system rollback and totalized fields An algebraic approach to system change Mark Burgess

摘要

In system operations the term rollback is often used to imply that arbitrary changes can be reversed i.e. 'rolled back' from an erroneous state to a previously known acceptable state. We show that this assumption is flawed and discuss error-correction schemes based on absolute rather than relative change. Insight may be gained by relating change management to the theory of computation. To this end, we reformulate previously-defined 'convergent change operators' of Burgess into the language of groups and rings. We show that, in this form, the problem of rollback from a convergent operation becomes equivalent to that of'division by zero' in computation. Hence, we discuss how recent work by Bergstra and Tucker on zero-totalized fields helps to clear up long-standing confusion about the options for 'rollback' in change management.