In this paper we present a simple and efficient method, called ARIES ( Algorithm for Recouery and Isolation Exploiting Semantics), which supports partial rollbacks of transactions, finegranularity (e.g., record) locking and recovery using write-ahead logging (WAL). We introduce the paradigm of repeating history to redo all missing updates before performing the rollbacks of the loser transactions during restart after a system failure. ARIES uses a log sequence number in each page to correlate the state of a page with respect to logged updates of that page. All updates of a transaction are logged, including those performed during rollbacks. By appropriate chaining of the log records written during rollbacks to those written during forward progress, a bounded amount of logging is ensured during rollbacks even in the face of repeated failures during restart or of nested rollbacks We deal with a variety of features that are very Important in building and operating an industrial-strength transaction processing system ARIES supports fuzzy checkpoints, selective and deferred restart, fuzzy image copies, media recovery, and high concurrency lock modes (e. g., increment /decrement) which exploit the semantics of the operations and require the ability to perform operation logging. ARIES is flexible with respect to the kinds of buffer management policies that can be implemented. It supports objects of

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developed at the IBM Almaden Research Center, which uses atomic tran.sactions as a unified failure recovery mechanism for a client-server structured distributed system. Transactions allow failure atomicity for related activities at a single server or at a number of independent servers. Rather than bundling transaction management into a dedicated language or recoverable object manager, Quicksilver exposes the basic commit protocol and log recovery primi-tives, allowing clients and servers to tailor their recovery techniques to their specific needs. Servers can implement their own log recovery protocols rather than being required to use a system-defined protocol. These decisions allow servers to make their own choices to balance simplicity, efficiency, and recoverability. Categories and Subject Descriptors: D.4.3 [Operating Systems]: File System Management-distrib-uted file systems; file organization; maintenance; D.4.5 [Operating Systems]: Reliability-FauZt-tolerance; checkpoint/restart; H.2.4 [Database Management]: Systems--distributed systems; trun.s-action processing

Abstract. Weighted voting is used as the basis for a replication technique for directories. This technique affords arbitrarily high data availability as well as high concurrency. Efficient algorithms are presented for all of the standard directory operations. A structural property of the replicated directory that permits the construction of an efficient algorithm for deletion is proven. Simulation results are presented and the system is modeled and analyzed. The analysis agrees well with the simulation, and the space and time performance are shown to be good for all configurations of the system.

. Database applications often impose temporal dependencies between transactions that must be satisfied to preserve data consistency. The extant correctness criteria used to schedule the execution of concurrent transactions are either time independent or use strict, difficult to satisfy real-time constraints. On one end of the spectrum, serializability completely ignores time. On the other end, deadline scheduling approaches consider the outcome of each transaction execution correct only if the transaction meets its real-time deadline. In this paper, we explore new correctness criteria and scheduling methods that capture temporal transaction dependencies and belong to the broad area between these two extreme approaches. We introduce the concepts of succession dependency and chronological dependency and define correctness criteria under which temporal dependencies between transactions are preserved even if the dependent transactions execute concurrently. We also propose a chronological s...

So much has already been written about everything that you can't nd out anything about it. | James Thurber, Lanterns and Lances (1961) Loosely-coupled distributed systems haveevolved using message passing as the main paradigm for sharing information. Other paradigms used in loosely-coupled distributed systems, such as rpc, are usually implemented on top of an underlying message-passing system. On the other hand, in tightly-coupled architectures, such asmulti-processor machines, the paradigm is usually based on shared memory with its attractively simple programming model. The shared-memory paradigm has recently been extended for use in more loosely-coupled architectures and is known as distributed shared memory (dsm [153, 178,58]) in this context. This chapter discusses some of the issues involved in the design and implementation of such adsm in loosely-coupled distributed systems and brie y discusses related work in other elds. In dsm systems, processes share data transparently across node boundaries � data faulting, location, and movement are handled by thedsm system. Among other things, this allows parallel programs designed to use the shared-memory abstraction to execute without modi cation on a

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