Gerald J. Popek

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Virtual machine systems have been implemented on a limited number of third generation computer systems, for example CP-67 on the IBM 360/67. The value of virtual machine techniques to ease the development of operating systems, to aid in program transferability, and to allow the concurrent running of disparate operating systems, test and diagnostic programs(More)
As we approach nation-wide integration of computer systems, it is clear that le replication will play a key role, both to improve data availability in the face of failures, and to improve performance by locating data near where it will be used. We expect that future le systems will have an extensible, modular structure in which features such as replication(More)
<bold>LOCUS is a distributed operating system which supports transparent access to data through a network wide filesystem, permits automatic replication of storage, supports transparent distributed process execution, supplies a number of high reliability functions such as nested transactions, and is upward compatible with Unix. Partitioned operation of(More)
Ficus is a flexible replication facility with optimistic concurrency control designed to span a wide range of scales and network environments. Optimistic concurrency control provides rapid local access and high availability of files for update in the face of disconnection, at the cost of occasional conflicts that are only discovered when the system is(More)
Many distributed systems are now being developed to provide users with convenient access to data via some kind of communications network. In many cases it is desirable to keep the system functioning even when it is partitioned by network failures. A serious problem in this context is how one can support redundant copies of resources such as files (for the(More)
Rumor is an optimistically replicated le system designed for use in mobile computers Rumor uses a peer model that allows oppor tunistic update propagation among any sites replicating les The paper outlines basic characteristics of replication systems for mobile computers describes the design and implementation of the Rumor le system and presents performance(More)
Ficus is a exible replication facility with optimistic concurrency control designed to span a wide range of scales and network environments. Support for partitioned operation is fundamental to the Ficus design but was not widely exercised in early Ficus use. This position paper reports recent experiences using Ficus in settings where some replicas are only(More)
SUMMARY This research proposes and tests an approach to engineering distributed le systems that are aimed at wide-scale, Internet-based use. The premise is that replication is essential to deliver performance and availability, yet the traditional conservative replica consistency algorithms do not scale to this environment. Our Ficus replicated le system(More)