SCR Algorithm：Saving／Restoring States of File Systems
摘要
Fault-tolerance is very important in cluster computing and has been implemented in many famous cluster-computing systems using checkpoint/restart mechanisms,But existent check-pointing algorithms cannot restore the states of a file system when roll-backing the running of a program,so there are many restrictions on file accesses in existent fault-tolerance systems.SCR algorithm,an algorithm based on atomic operation and consistent schedule,which can restore the states of file systems,is presented into idem-potent operations and non-idem-potent operations.systems are classified into idem-potent operations and non-idem-potent operations.A non-idem-potent operation modifies a file system's states,while an idem-potent operation does not.SCR algorithm tracks changes of the file system states.It logs each non-idem-potent operation used by user programs and the information that can restore the operation in disks.When check-pointing roll-backing the program,SCR algorithm will revert the file system states to the last checkpoint time.By using SCR algorithm,users are allowed to use any file operation in their programs.