A Practical guide to the design of differential files for recovery of online databases

http://deepblue.lib.umich.edu/bitstream/2027.42/35347/2/b1377036.0001.001.pdfhttp://deepblue.lib.umich.edu/bitstream/2027.42/35347/1/b1377036.0001.001.tx

Differential Files: Applications and Analysis.

The representation of a collection of data in terms of its differences from a preestablished point of reference is a basic storage compaction technique with wide applicability. This dissertation studies a differential file architecture which has been suggested as an efficient means of storing large and volatile databases. A comprehensive analysis of this scheme is provided, and key decision variables in the design of an efficient differential file architecture are identified. An analytic model for the differential file operation is developed. Solution procedures, based on st and ard numerical search techniques and heuristics, are provided which can quickly generate (near) optimal differential file design. Applying the results to realistic problems, the potential for a modest reduction in operating cost, and significant improvements in database recovery and access times are demonstrated.Ph.D.Computer scienceUniversity of Michiganhttp://deepblue.lib.umich.edu/bitstream/2027.42/158571/1/8204584.pd

Clock Synchronization in the Presence of Omission and Performance Failures, and Processor Joins

This paper presents a simple practical protocol for synchronizing clocks in a distributed system. Synchronization consists of maintaining logical clocks which run at roughly the speed of a correct hardware clock and are within some known bound of each other. Synchronization is achieved by periodically computing adjustments to the hardware clocks present in the system. The protocol is tolerant of any number of omission failures (e.g. processor crashes, link crashes, occasional message losses) and performance failures (e.g. overloaded processors, slow links) that do not partition the communications network and handles any number of simultaneous processor joins. An earlier version of this paper was ppresented at the 16th IEEE Int. Symp. on Fault-tolerant Computing Systems, Vienna, July 1-4, 1986. Flaviu Cristian is now with the University of California, San Diego. Houtan Aghili is now with IBM Research, T. J. Watson Research Center. 1 Introduction Consider a set of processors interconn..

Atomic Broadcast: From Simple Message Diffusion to Byzantine Agreement

In distributed systems subject to random communication delays and component failures, atomic broadcast can be used to implement the abstraction of synchronous replicated storage, a distributed storage that displays the same contents at every correct processor as of any clock time. This paper presents a systematic derivation of a family of atomic broadcast protocols that are tolerant of increasingly general failure classes: omission failures, timing failures, and authentication-detectable Byzantine failures. The protocols work for arbitrary point-to-point network topologies, and can tolerate any number of link and process failures up to network partitioning. After proving their correctness, we also prove two lower bounds that show that the protocols provide in many cases the best possible termination times. Keywords and phrases: Atomic Broadcast, Byzantine Agreement, Computer Network, Correctnesss, Distributed System, Failure Classification, Fault-Tolerance, Lower Bound, Real-Time Syste..