recovery - Recovery CSCI 5105 Foundations of Modern...

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1 CSCI 5105 Foundations of Modern Operating Systems Instructor: Abhishek Chandra 2 Recovery Operations to be performed to move from an erroneous state to an error-free state Backward recovery: Go back to a previous correct state E.g.: packet retransmission Forward recovery: Go to a new correct state E.g.: Error-correction codes 3 Recovery techniques Checkpointing Message logging Rebooting 4 Checkpointing Periodically store state on stable storage Mirrored/RAID disks, etc. At error-recovery, go back to the last checkpointed state Problem: How do we rollback so that all process go back to a consistent global state?
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2 5 Cuts in Global State Space Cut: Partition of events representing a global state Set of last recorded event for each process 6 Distributed Snapshot Consistent cut: Receipt of a message m in the cut => sending of m also in the cut If event a is in the cut, then all b s.t. b->a are in the cut Distributed Snapshot:
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recovery - Recovery CSCI 5105 Foundations of Modern...

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