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1993 ACM SIGMETRICS Conference on Measurement and Modeling of Computer systems, SIGMETRICS 1993

作者： Biswas, Prabuddha Ramakrishnan, K.K. Towsley, Don Office and Teamware Engineering Group Digital Equipment Corporation 110 Spitbrook Road NashuaNH United States Distributed Systems Architecture and Performance Group Digital Equipment Corporation 550 King Street LittletonMA United States Computer Science Department University of Massachusetts AmherstMA United States

ISBN: (纸本)0897915801

The I/O subsystem in a computer system is becoming the bottleneck as a result of recent dramatic improvements in processor speeds. Disk caches have been effective in closing this gap but the benefit is restricted to the read operations as the write I/Os are usually committed to disk to maintain consistency and to allow for crash recovery. As a result, write I/O traffic is becoming dominant and solutions to alleviate this problem are becoming increasingly important. A simple solution which can easily work with existing file systems is to use non-volatile disk caches together with a write-behind strategy. In this study, we look at the issues around managing such a cache using a detailed trace driven simulation. Traces from three different commercial sites are used in the analysis of various policies for managing the write cache. We observe that even a simple write-behind policy for the write cache is effective in reducing the total number of writes by over 50%. We further observe that the use of hysteresis in the policy to purge the write cache, with two thresholds, yields substantial improvement over a single threshold scheme. The inclusion of a mechanism to piggyback blocks from the write cache with read miss I/Os further reduces the number of writes to only about 15% of the original total number of write operations. We compare two piggybacking options and also study the impact of varying the write cache size. We briefly looked at the case of a single non-volatile disk cache to estimate the performance impact of statically partitioning the cache for reads and writes. © 1993 ACM.

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File access characterization of VAX/VMS environments

File access characterization of VAX/VMS environments

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International Conference on distributed Computing systems

作者： P. Biswas K.K. Ramakrishnan Business and Office Systems Engineering Functional Analysis Group Digital Equipment Corporation Nashua NH USA Distributed Systems Architecture and Performance Group Digital Equipment Corporation Littleton MA USA

A comprehensive analysis of file access behavior of several commercial production VAX/VMS environments, based on detailed I/O traces, is presented. The characterization focuses on file control operations (such as opens and closes) which are often expensive in both processing and I/O requirements. The motivation for this analysis is the need to design good data management algorithms for distributed file systems. These algorithms are particularly important for managing client caches. Most of the operations for managing client caches are performed on file opens and closes. The authors present quantitative data on the number of file opens and closes, their timing characteristics, and their declared intent to allow sharing or have exclusive access. The precise dynamic sharing of files is examined.< >

关键词： Voice mail File systems Production systems Algorithm design and analysis Availability File servers Network servers Business systems engineering and theory Functional analysis

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THE “JIMMIE” HAMILTON AWARD FOR 1983

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Naval Engineers Journal 1984年第4期96卷

作者： CAPT. JAMES KEHOE JR. KENNETH S. BROWER EDWARD N. COMSTOCK USN (RET.) Captain James W. Kehoe Jr. USN (Ret:.) is well known for his work in conducting comparative naval architecture studies of U.S. and foreign warships design practices for which he received the ASNE Gold Medal for 1981 and the Legion of Merit. He is currently a partner in Spectrum Associates Incorporated Arlington Virginia where he engaged in the feasibility and concept design of naval ships and in continuing his comparative engineering analyses of U.S. and foreign warships. Prior to his retirement from the U.S. Navy in 1982 his naval career involved sea duty aboard three destroyers and three aircraft carriers including command of the USSJohn R. Pierce(DD-753) and engineer officer of the USSWasp(CVS-18). Ashore he had duty at the Naval Sea Systems Command where he directed the Comparative Naval Architecture Program as an instructor in project management in the Polaris missile project and as a nuclear weapons officer. A frequent contributor to theNaval Engineers Journal U.S. Naval Institute Proceedings and theInternational Defense Review he has published a number of articles on U.S. Soviet and other foreign design practices and the effects of design practices on ship size and cost. He has been a member of ASNE since 1974. Kenneth S. Brower:is a partner in Spectrum Associates Incorporated Arlington Virginia which he founded in June 1978. He graduated from the University of Michigan in 1965 with a Bachelor's Degree in Naval Architecture. Mr. Brower has contributed to the design and construction of numerous merchant ships and warships the latter of which include the CG-47 Project Arapaho (in both cases as feasibility design manager) the FDL and DX projects and the new NATO Frigate Replacement for the 90s DDGX and FFX projects. He conceived and directed the development of several frigates and corvettes for foreign military sales. Mr. Brower directed the development of unique reverse engineering ship design computer models and the development of Spectrum Associates' own keel-up Ship Desi

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SEAKEEPING AND COMBAT SYSTEM performance - THE OPERATORS ASSESSMENT

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NAVAL ENGINEERS JOURNAL 1983年第3期95卷 256-266页

作者： KEHOE, JW BROWER, KS COMSTOCK, EN Capt. James W. Kehoe Jr. USN (Ret.):is well known for his work in conducting comparative naval architecture studies of U.S. and foreign warship design practices for which he received the ASNE GoldMedalfor 1981 and the Legion ofMerit. He is currently a partner in Spectrum Associates Incorporated Arlington Virginia where he is engaged in the feasibility and concept design of naval ships and in continuing his comparative engineering analyses of U.S. and foreign warships. Prior to his retirement from theU.S. Navyas a Captain in 1982 his naval career involved sea duty aboard three destroyers and three aircraft carriers including command of theUSS John R. Pierce (DD-753)and engineer officer of theUSS Wasp (CVS-18). Ashore he had duty at the Naval Sea Systems Command where he directed the Comparative Naval Architecture Program as an instructor in project management in the Polaris missile project and as a nuclear weapons officer. He holds a B.S. in mathematics from Stonehill College Massachusetts (1952) and an MA in education from San Diego State College (1959). A frequent contributor to theNaval Engineers Journal U.S. Naval Institute Proceedings and theInternational Defense Review he has published a number of articles on U.S. Soviet and other foreign warship design practices and the effects of design practices on ship size and cost. Mr. Kenneth S. Brower:is a partner in Spectrum Associates Incorporated Arlington Virginia which he founded in June 1978. He graduated from the University of Michigan in 1965 with a Bachelor's Degree in Naval Architecture. Mr. Brower has contributed to the design and construction of numerous merchant ships and warships the latter of which include theCG-47 projectArapaho theFDLand DX projects the new NATO Frigate Replacement for the 90's DDGX and FFX projects as well as several frigates developed for Foreign Military Sales. Since 1972 he has actively supported the Naval Sea Systems Command's Comparative Naval Architecture Proram. During this period Mr. Brower has cont

In a recent effort to improve our assessment of the Comparative seakeeping performance of existing U.S. N avy ships, a seakeeping questionnaire was distributed to the Commanding Officers of U.S. N avy frigates, destroyers, and cruisers. The objectives were to determine, (1) the operational availability of existing weapons and sensors in relation to a ship's seakeeping performance, (2) the availability of ships to make full speed and to conduct sonar, helicopter, and replenishment-at-sea operations, (3) effects of a ship's seakeeping limitations on task force and convoy operation, and (4) realistic seakeeping design crteria for use in the design of new ships. The responses to the questionnaire indicated that frigates are severely limited in their availability to conduct ASW task force and convoy operations in the North Atlantic during the winter season because of seakeeping limitations on speed, hull sonar performance, and helicopter operations. The findings suggest that in the design of future ships we need to place emphasis on improving the seakeeping performance of ships in rough water, instead of just their speed and range in calm water. They indicate that the ASW capability of U.S. ships in high sea states would be enhanced by a towed acoustic sensor; an extended range ASW missile; active fin roll stabilizers; and a helicopter recovery assistance, securing and traverse (RAST) system. They also suggest that the question of the interaction of a ship's size and seakeeping characteristics with the choice of weapons and sensors requires careful attention in the design of future U.S. N avy ships.

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