SCR Algorithm: Saving/Restoring States of File Systems  

作　　者：魏晓辉 鞠九滨 

出　　处：《Journal of Computer Science & Technology》2000年第4期393-400,共8页计算机科学技术学报（英文版）

摘　　要：Fault-tolerance is very important in cluster computing and has beenimplemented in many famous cluster-computing systems using checkpoint/restartmechanisms. But existent check-pointing algorithms cannot restore the states of afile system when roll-backing the running of a program, so there are many restrictionson file accesses in existent fault-tolerance systems. SCR algorithm, an algorithmbased on atomic operation and consistent schedule, which can restore the states offile systems, is presented in this paper. In the SCR algorithm, system calls on filesystems 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-potentoperation does not. SCR algorithm tracks changes of the file system states. It logseach non-idem-potent operation used by user programs and the information that canrestore the operation in disks. When check-pointing roll-backing the program, SCRalgorithm will revert the file system states to the last checkpoint time. By usingSCR algorithm, users are allowed to use any file operation in their programs.Fault-tolerance is very important in cluster computing and has beenimplemented in many famous cluster-computing systems using checkpoint/restartmechanisms. But existent check-pointing algorithms cannot restore the states of afile system when roll-backing the running of a program, so there are many restrictionson file accesses in existent fault-tolerance systems. SCR algorithm, an algorithmbased on atomic operation and consistent schedule, which can restore the states offile systems, is presented in this paper. In the SCR algorithm, system calls on filesystems 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-potentoperation does not. SCR algorithm tracks changes of the file system states. It logseach non-idem-potent operation used by user programs and the information that canrestore the operation in disks. When check-pointing roll-backing the program, SCRalgorithm will revert the file system states to the last checkpoint time. By usingSCR algorithm, users are allowed to use any file operation in their programs.

关 键 词：FAULT-TOLERANCE check-pointing atomic operation recoverability of file systems 

分 类 号：TP301[自动化与计算机技术—计算机系统结构]