JASMIN is a functionally distributeddatabase machine consisting of a three-level hierarchical architecture in which each level can be implemented by any number of real processors. Improving performance by the replica...
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ISBN:
(纸本)0818605642
JASMIN is a functionally distributeddatabase machine consisting of a three-level hierarchical architecture in which each level can be implemented by any number of real processors. Improving performance by the replication of data is discussed. The benefit is reduced access time resulting from increased availability of the data. The cost is the overhead of keeping copies mutually consistent. JASMIN is different in that it uses a distributed optimistic concurrency control method combined with a versioning scheme. The authors describe how they integrate replicated data into JASMIN's concurrency control, commit, and recovery subsystems.
The authors introduce a new concept in naming for distributedsystems. which is motivated by the need for easily-migratable objects, which is in turn motivated by the need for reliable operations. This naming scheme a...
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ISBN:
(纸本)0818605642
The authors introduce a new concept in naming for distributedsystems. which is motivated by the need for easily-migratable objects, which is in turn motivated by the need for reliable operations. This naming scheme attempts to solve certain problems associated with correcting remote references to objects which are subject to migration. A name is divided into two parts, of which the first is used to locate the possible current sites of a target object and the second is used to select the specific site (and hence the object) in which the object is to be found. The set of possible sites constitutes a cluster. The authors discuss how clusters and cluster-based naming can be applied to enhance the migratability, and thus reliability, of a system in our context. The same scheme may be applied for other purposes such as load-balancing, protection, and support of transparent services.
The authors consider the problems of partitioning and processor failure in a loosely-coupled distributed system using a synchronous Send/Receive/Reply style of interprocess communication. These problems are described ...
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ISBN:
(纸本)0818605642
The authors consider the problems of partitioning and processor failure in a loosely-coupled distributed system using a synchronous Send/Receive/Reply style of interprocess communication. These problems are described in a client-server setting using both connectionless and connection-based protocols. To solve these problems, the concept of unique and non-reusable process identifiers is utilized. A solution using agent processes is currently implemented in Waterloo Port, a network operating system. The authors propose a new solution that does not impose a significant performance penalty on message-passing and does not require any additional processes.
A distributed algorithm for deadlock detection and resolution in distributeddatabasesystems.is presented that has the following advantages: (1) Every site maintains only local information and need not maintain any g...
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ISBN:
(纸本)0818605642
A distributed algorithm for deadlock detection and resolution in distributeddatabasesystems.is presented that has the following advantages: (1) Every site maintains only local information and need not maintain any global information. (2) Messages exchanged between sites are of short and fixed length. (3) The correctness of the algorithm is ensured even if side effects of deadlock resolution are taken into account. (4) The number of messages needed to detect deadlocks decreases as the ratio of local transactions to global transactions increases. (5) There is only one resolver for each deadlock. The performance of this algorithm with respect to time and communication complexities is analyzed.
A system is presented that involves a debugging tool to help detect logical errors and remove them efficiently. The debugging tool is supported by a special architecture named SPRING, which was originally developed fo...
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ISBN:
(纸本)0818605642
A system is presented that involves a debugging tool to help detect logical errors and remove them efficiently. The debugging tool is supported by a special architecture named SPRING, which was originally developed for reliable execution of Ada or Pascal programs. Following an overview of the system backed up by SPRING, the implementation of high-level debugging on the SPRING architecture is discussed in detail. In conclusion, the trial is seen as a step toward an advanced programming environment for the development of reliable software.
The TABS prototype is an experimental facility that provides operating-system level support for distributed transactions operating on shared abstract types. It is hoped that the facility will simplify the construction...
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ISBN:
(纸本)0818605642
The TABS prototype is an experimental facility that provides operating-system level support for distributed transactions operating on shared abstract types. It is hoped that the facility will simplify the construction of available, reliable, distributed applications. The authors describe the TABS system model, the structure of the prototype, and certain aspects of its operation. They conclude with an evaluation of the status of the TABS project.
作者：
Barbara, DanielGarcia-Molina, HectorPrinceton Univ
Dep of Electrical Engineering & Computer Science Princeton NJ USA Princeton Univ Dep of Electrical Engineering & Computer Science Princeton NJ USA
In a faulty distributed system, voting is commonly used to achieve mutual exclusion among groups of nodes. Each node is assigned a number of votes, and any group with a majority of votes can perform the critical opera...
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ISBN:
(纸本)0818605642
In a faulty distributed system, voting is commonly used to achieve mutual exclusion among groups of nodes. Each node is assigned a number of votes, and any group with a majority of votes can perform the critical operations. Vote assignments can have a significant impact on system reliability. To compare vote assignments, the authors define two deterministic metrics, node and edge, vulnerability. They present various properties of these metrics and discuss how they can be computed. For these metrics, they discuss the selection of the best assignment and propose heuristics to identify good candidate assignments. Finally, they summarize experimental results that indicate that the heuristics yield optimal or close to optimal assignments.
A technique is described for implementing k-resilient objects, i. e. , distributed objects that remain available, and whose operations are guaranteed to progress to completion, despite up to k site failures. The imple...
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ISBN:
(纸本)0818605642
A technique is described for implementing k-resilient objects, i. e. , distributed objects that remain available, and whose operations are guaranteed to progress to completion, despite up to k site failures. The implementation is derived from the object specification automatically, and does not require any information beyond what would be required for a nonresilient, nondistributed implementation. It is therefore unnecessary for an applications programmer to have knowledge of the complex protocols normally used to implement fault-tolerant objects. The technique is used in ISIS, a system being developed at Cornell to support resilient objects.
Several protocols that ensure that a database can be recovered to a consistent state after a transaction failure or system crash are compared. The study includes a collection of simple analytic models, based on Markov...
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ISBN:
(纸本)0818605642
Several protocols that ensure that a database can be recovered to a consistent state after a transaction failure or system crash are compared. The study includes a collection of simple analytic models, based on Markov processes, for these protocols and some surprising results on the relative performance of the protocols. The authors consider only two-stage transactions (all reads before writes) and ignore effects of serializing transactions. The most interesting performance result presented is that, for systems.obeying the assumptions of this paper, the 'pessimistic' policy of holding write locks to commit point is considerably less efficient than the 'optimistic' policy that allows reading of uncommitted data but risks cascading aborts. A multiversion policy was also studied and found always to be nearly as good as the optimistic policy and sometimes much better.
作者：
McKendry, Martin S.Georgia Inst of Technology
Sch of Information & Computer Science Atlanta GA USA Georgia Inst of Technology Sch of Information & Computer Science Atlanta GA USA
Examples to illustrate requirements for ordering mechanisms are introduced. A model of nested actions is then used as a basis for categorizing visibility requirements. These requirements go beyond those typical of dat...
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ISBN:
(纸本)0818605642
Examples to illustrate requirements for ordering mechanisms are introduced. A model of nested actions is then used as a basis for categorizing visibility requirements. These requirements go beyond those typical of databasesystems. because often the entities managed by operating systems.cannot be recovered if an action fails. Several simplifications that apply to many operating system problems are discussed. Algorithms for controlling ordering are then presented, with examples of their use. Several expediencies that result from ordering requirements are established. In many situations, recovery for nested actions can be implemented with a single backup copy of each item, a single synchronization variable can be used to control blocking, and generalized locking is not required. These savings appear to be fundamental to making the object-action approach viable for operating system construction.
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