When a procedure is being executed inside of a system of any scale, there are points where failure recovery may be difficult or impossible.  There are many patterns that apply to recovery from failure, and many are visible in TransactionalSystems.

   o Rollback to a safe point and try again.
   o Start Over when everything done so far can be redone.
   o Undo everything done so far and start over.

Some other variations are visible in such places as software installation applications, database systems and in device driver setup code.

GreggWonderly