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Replication has been shown to be an important tool in the design of high-performance and highly-available distributed systems. When applied to data, however, replication significantly complicates the problem of maintaining consistency within a system. This problem is further complicated when repositories of the data can potentially fail and recover. In this dissertation, we describe a log-based mechanism for restoring consistent states to replicated data objects after failures. (rrh)

A log-based mechanism is described for restoring consistent states to replicated data objects after failures. Preserving a causal form of consistency based on the notion of virtual time is focused upon in this report. Causal consistency has been shown to apply to a variety of applications, including distributed simulation, task decomposition, and mail delivery systems. Several mechanisms have been proposed for implementing causally consistent recovery, most notably those of Strom and Yemini, and Johnson and Zwaenepoel. The mechanism proposed here differs from these in two major respects. First, a roll-forward style of recovery is implemented. A functioning process is never required to roll-back its state in order to achieve consistency with a recovering process. Second, the mechanism does not require any explicit information about the causal dependencies between updates. Instead, all necessary dependency information is inferred from the orders in which updates are logged by the object servers. This basic recovery technique appears to be applicable to forms of consistency other than causal consistency. In particular, it is shown how the recovery technique can be modified to support an atomic form of consistency (grouping consistency). By combining grouping consistency with casual consistency, it may even be possible to implement serializable consistency within this mechanism.

A log-based mechanism is described for restoring consistent states to replicated data objects after failures. Preserving a causal form of consistency based on the notion of virtual time is focused upon in this report. Causal consistency has been shown to apply to a variety of applications, including distributed simulation, task decomposition, and mail delivery systems. Several mechanisms have been proposed for implementing causally consistent recovery, most notably those of Strom and Yemini, and Johnson and Zwaenepoel. The mechanism proposed here differs from these in two major respects. First, a roll-forward style of recovery is implemented. A functioning process is never required to roll-back its state in order to achieve consistency with a recovering process. Second, the mechanism does not require any explicit information about the causal dependencies between updates. Instead, all necessary dependency information is inferred from the orders in which updates are logged by the object servers. This basic recovery technique appears to be applicable to forms of consistency other than causal consistency. In particular, it is shown how the recovery technique can be modified to support an atomic form of consistency (grouping consistency). By combining grouping consistency with casual consistency, it may even be possible to implement serializable consistency within this mechanism.

1For Greater Things: The Story of Saint Stanislaus Kostka

By William T. Kane

Saint Stanislaus Kostka was a 16th century Polish novice in the Society of Jesus. Polish nobleman John Kostka was not pleased with the spiritual inclinations of his second son. He did all he could to discourage Stanislaus’s desire for Christian service. Paul, a brother two years older than Stanslaus, bullied him and tried to lure him into more worldly pursuits. Stanislaus was determined to join the Society of Jesus. To demonstrate his determination, Stanislaus walked the long and dangerous 350 miles from Vienna to Rome. He made the trip alone depending on the charity of others and there was accepted into the Society of Jesus as a novice on his 17th birthday. During his short time as a novice his religious fervor and piety were amazing. He was beatification in 1605; and he canonized on 31 December 1726. - Summary by Wikipedia and Phil Chenevert

Johnny Liddell, the fast-moving New York private eye, is hired to investigate a murder which everyone but the client calls a suicide. The client, a beautiful heiress, unfortunately fails to appear at a rendezvous to explain matters; instead a very active tommy-gun enlivens the proceedings. Score: one gunman killed, Liddell unscathed. The gangsters turn out to be members of a syndicate run from Sing Sing, but their connection with the girl is not clear. And she, by this time, has vanished completely, leaving the detective with nothing but a $500 retainer. With his usual keenness Johnny moves from this lively beginning on a violent trail of fights and point-blank killings from Park Avenue to Broadway, leading to a very unexpected climax. - Summary from inside front flap of book

Johnny Liddell cleans up the crime-ridden New York water front by making a dope charge stick against the head of the "organization", the group masterminding the big-time rackets. Liddell naturally arouses a grim determination to get rid of him via beating, fighting, and general mayhem on the part of the lowest mug as well as the remote Marty Regan, boss of the organization. With the cooperation of a crusading newspaper, an honest inspector, and a maritime insurance company, he boldly puts the finger on Regan. In this slam-bang story of suspense, Mr. Kane pulls aside the curtain to show how crime got its stranglehold on the city. - Summary by Inside sleeve of first edition

A Case of Corpses... They piled up so fast that private-eye Johnny Liddell figured he was ahead if he found them still warm. It started when he was hired as baby-sitter to a wildcat. She was blond and beautiful, and stacked better than a deck of marked cards. And she had a cool $200,000 worth of hot diamonds. There was just one hitch. She used bourbon instead of perfume. (Summary by Rear cover, 1955 Dell paperback edition)