The quantification of distributed Data Base (DDB) reliability is needed for the DDB design phase and for the comparative evaluation of the effectiveness of various data distribution strategies. A method based on a Mar...
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The quantification of distributed Data Base (DDB) reliability is needed for the DDB design phase and for the comparative evaluation of the effectiveness of various data distribution strategies. A method based on a Markov model is outlined to evaluate the transition probabilities from a functioning system to a faulty one and viceversa. The method consists of two steps: first is the computation of the transition rate matrix of the DDB with Kronecker algebra, which is used then to calculate the probabilities of the different possible states of the DDB;the second is an algorithm to calculate the structure vector related to a given transaction of the DDB.
作者：
Lin, James J.Liu, Ming T.Ohio State Univ
Dep of Computer & Information Science Columbus OH USA Ohio State Univ Dep of Computer & Information Science Columbus OH USA
The system design and performance evaluation of a local data network for very large distributeddatabases. The growing database problem stimulates the need of hardware support for data management in distributed system...
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The system design and performance evaluation of a local data network for very large distributeddatabases. The growing database problem stimulates the need of hardware support for data management in distributedsystems. A novel hardware configuration, the distributed Double-Loop Data Network (DDLDN), is exemplified. Concurrency control mechanisms and query processing techniques used in the DDLDN are described. Optimal strategy for disk allocation is selected. A performance comparison is made for different types of systems.under various conditions, showing superior performance of the DDLDN. Finally, a way to cope with potential growth of the system is demonstrated.
Some ideas on the construction of user applications as atomic actions are developed. Atomic actions that last a long time pose several problems if conventional ideas on concurrency control and recovery are applied. Wh...
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Some ideas on the construction of user applications as atomic actions are developed. Atomic actions that last a long time pose several problems if conventional ideas on concurrency control and recovery are applied. What is required is some means of delaying commitment without sacrificing performance. A model is proposed in which it is possible for an action to release and process as yet uncommitable objects. The impact of this on recovery is also discussed.
作者：
Minoura, ToshimiUniv of Southern California
Dep of Electrical Engineering-Systems Los Angeles CA USA Univ of Southern California Dep of Electrical Engineering-Systems Los Angeles CA USA
Two schemes for realizing mutual exclusion in a distributed system are discussed. The ranking scheme is a common framework for the three mutual exclusion algorithms found in the literature. In the ranking scheme, the ...
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Two schemes for realizing mutual exclusion in a distributed system are discussed. The ranking scheme is a common framework for the three mutual exclusion algorithms found in the literature. In the ranking scheme, the site with the smallest rank number can enter the mutual exclusion state. Another method of realizing mutual exclusion is to let a single 'control token' float in the system and to allow only its holder to enter the mutual exclusion state. One result in this paper shows how the control token is effectively transferred by the ranking scheme.
Two-Phase Commit and other distributed commit protocols provide a method to commit changes while preserving consistency in a distributeddatabase. These protocols can cope with various failures occurring in the system...
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Two-Phase Commit and other distributed commit protocols provide a method to commit changes while preserving consistency in a distributeddatabase. These protocols can cope with various failures occurring in the system. But in case of failure they do not guarantee termination (of protocol processing) within a given time: sometimes the protocol requires waiting for a failed processor to be returned to operation. It happens that a straightforward use of timeouts in a distributed system is fraught with unexpected peril and does not provide an easy solution to the problem. Byzantine Agreement is combined with Two-Phase Commit, using observations of Lamport to provide a method to cope with failure within a given time bound. An extra benefit of this combination of ideas is that it handles undetected and transient faults as well as the more usual system or processor down faults handled by other distributed commit protocols.
Intuition tells us that in a distributed DBMS using two phase locking, the ratio (denoted by R/W) of read-only to update transactions affects system performance - the higher the ratio, the better the performance. Read...
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Intuition tells us that in a distributed DBMS using two phase locking, the ratio (denoted by R/W) of read-only to update transactions affects system performance - the higher the ratio, the better the performance. Read-only transactions only request share locks, and thus should cause fewer conflicts and deadlocks among all transactions. Therefore both read-only and update transactions are expected to perform better if R/W is higher. The results of a study contradicting this intuition are reported, and the relationship between the R/W ratio and system performance in detail.
The Byzantine Generals problem involves a system of N processes, t of which may be unreliable. The problem is for the reliable processes to agree on a binary value sent by a 'general' which may itself be one o...
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The Byzantine Generals problem involves a system of N processes, t of which may be unreliable. The problem is for the reliable processes to agree on a binary value sent by a 'general' which may itself be one of the N processes. If the general sends the same value to each process, then all reliable processes must agree on that value but in any case, they must agree on the same value. An explicit solution is given for a binary value among N equals 3t plus 1 processes, using 2t plus 4 rounds and O(t**3 log t) message bits, where t bounds the number of faulty processes. This solution is easily extended to the general case of N greater than equivalent to 3t plus 1 to give a solution using 2t plus 5 rounds and O(tN plus t**3 log t) message bits.
proceedings includes 30 papers, one of which appears in abstract form only, dealing with current topics and achievements in promoting the reliability of distributedsoftware and data base systems. Topics considered in...
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proceedings includes 30 papers, one of which appears in abstract form only, dealing with current topics and achievements in promoting the reliability of distributedsoftware and data base systems. Topics considered include: computer networks, protocols, computer programming and programming languages, microprocessors, Petri nets, mathematical trees, fault tolerance, data base management, data networks, modeling, and algorithms. Technical and professional papers from this conference are indexed with the conference code no. 00660 in the Ei Engineering Meetings (TM) database produced by Engineering Information, Inc.
Distribution of computing to achieve goals such as enhanced reliability depend on the use of decentralized software. Decentralization typically replaces a sequential process by a system of small, concurrent processes ...
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A new concurrency control algorithm for distributeddatabasesystems.that spatially extends the idea of ″exclusive/share locks″ is presented. The new algorithm, extended true-copy token algorithm, combines a locking...
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A new concurrency control algorithm for distributeddatabasesystems.that spatially extends the idea of ″exclusive/share locks″ is presented. The new algorithm, extended true-copy token algorithm, combines a locking mechanism and a ″true-copy token″ mechanism. ″True-copy tokens″ handle partitioned data that cannot be handled efficiently by locks alone.
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