Duchamp D., Tait C. D. "An Interface to Support Lazy Replicated File Service, " Proc. 2nd IEEE Workshop on Management of Replicated Data, Monterey, CA, November 1992.  Home/Search   Document Details and Download   Summary   Related Articles   Check

....requirements. These services mainly address the management of the data objects and files in the presence of mobility. They are also responsible for negotiating with MSSs the quality of the service according to both user requirements and services actually supplied by the wireless network [7, 13, 15, 22, 28, 29, 32]. The problem of locating MHs, i.e. of knowing their current position to allow the routing of the messages, has received great attention [5, 25] and is emphasized by the trend of reducing the cell s size to improve the communication bandwidth. Location service is architecturally located within ....

....may lead to the violation of the database correctness. As a consequence, the efforts to achieve fault tolerance have been addressed to redesign the notion of correctness rather than to redefine the notion of failure. A number of alternative definitions of ACID properties have been proposed [15, 21, 30, 33] that weaken one or more of the properties. In general, their goal is to guarantee the MHs a certain degree of autonomy in transaction processing during disconnections, and to preserve the (modified) system correctness by allowing bounded inconsistencies among the data copies. In the following, ....

Duchamp D., Tait C. D. "An Interface to Support Lazy Replicated File Service, " Proc. 2nd IEEE Workshop on Management of Replicated Data, Monterey, CA, November 1992.

....in [13] a variable consistency scheme for mobile environments is proposed, and [24] discusses different ways to keep consistency by efficiently exploiting different network connectivity. In our system, we adopt two different sharing semantics. When network connection is available, the strict CTO[23] semantics is supported. If the client system goes off network, it is impossible to keep CTO semantics with server. Therefore, all file access operations will be executed locally in an uncommitted 8 Parameters Description Values thinkTime thinking interval time 60 workTime working interval time ....

....immediately using the existing approaches and to solve conflicts[3, 25, 22] In the following, we only address the situation when a client can connect to a server in the wired network. In our system, we use different strategies to keep data files and directories consistency. We adopt CTO semantics[23] to keep data files consistent in adaptive volumes. The CTO semantics is also used in NFS[2] and Sprite[14] Following CTO semantics, the consistency checking will be triggered only by read and write operations on data files. For directories, we assume that the structure of the file hierarchy is ....

Dan Duchamp and Carl D. Tait. An Interface to Support Lazy Replicated File Service. In Proceedings of The Second Workshop on Management of Replicated Data, IEEE Monterey CA, Nov 1992, pp.6-8.

....However, there are several interesting projects, some ongoing, which are related to this task. Duchamp et al. 45, 1] have proposed the notion of introducing a proxy between the mobile client and the servers on the wired network, which delays writing out all but the most important data. In [38] they show its use in creating a lazy replicated file service. However, their system is based on Mach. Similar ideas, without the constraint of a particular OS choice, have been presented in our work on the theme of disconnected browsing [28, 24] however, they are specific to information ....

C. Tait and D. Duchamp, An Interface to Support Lazy Replicated File Service, Proc. Second Workshop on Management of Replicated Data (Monterey, CA), IEEE, November 1992, pp. 6--8.

....how sophisticated they become, simply because the mobile computers will be at least a step behind the mainstream computers. The supporting personnel will have to work harder to maintain a reasonably good mobile environments where the people and their computers may wander wherever they wish. In [40] Duchamp and Tait argue that, assuming low sharing workloads at the mobile computers, it is possible to build more efficient implementations that provide the same (or stronger) semantics by making fullest use of the assumption. Accordingly, they take an extreme point on the spreading searching ....

D. Duchamp and C. D. Tait, An Interface to Support Lazy Replicated File Service, Second Workshop on the Management of Replicated Data (Los Alamitos, CA, USA), IEEE, IEEE Comput. Soc. Press, 1992, pp. 6--8.

.... some of the performance benefits of write backs without consuming the same amount of bandwidth [7] By simply sending a small notification to the file server that a file has been modified, the server may be able to help reduce conflicts (especially if the server is allowed to initiate write backs [18, 17]) The performance benefit of using write notifications would depend on the amount of file sharing which occurs in the mobile environment. Prefetching Policy The availability of a fast network, combined with the difficulties of predicting future file system requests, has prevented prefetching ....

Tait, C., and Duchamp, D. An interface to support lazy replicated file service. In Proc. Second Workshop on Management of Replicated Data (Monterey, CA, Nov. 1992).

....conflict. Studies have shown that such conflicts occur only rarely [21, 24, 46] and that optimistic replication is a good strategy for a disconnected environment. However, some write write conflicts do occur, and these must be resolved. This is an issue which has been studied extensively [8, 16, 26, 29, 33, 40, 41, 43, 49, 50, 51], with current work focusing on the development of application specific resolvers [25] 2.3.2 Weakly Connected Operation Mobile clients differ from desktop workstations in two main ways. First, mobile clients tend to be resource poor compared to desktop workstations. Processing power, memory and ....

....relevant to the development of a prefetching algorithm for a mobile client s file cache. 2.7.3 Columbia University s Mobile File System Columbia University has also developed a distributed file system with support for mobile computing. Much of the work centres on efficient file replica management [51, 49, 50]. A unique feature of this file system is the write back mechanism, which is server based rather than client based; that is, the server notifies the client when a modified file should be written back (based on when it is convenient for the server) The server also informs the client when a ....

C. Tait and D. Duchamp. An interface to support lazy replicated file service. In Proc. Second Workshop on Management of Replicated Data, Monterey, CA, Nov. 1992.

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