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Distributed Caching

An immediate problem with having the persistent store separate from the execution unit is that data transfer now not only incurs disk latency, but also network latency and the effect of the network's smaller bandwidth. Just as a distributed file system may implement caching to reduce network traffic, we introduce a Virtual Disk Cache. The Virtual Disk Cache is distributed over many hosts (to service many potential clients) and operates on data divided into 4K pages.

PerDiS [3] provides a very similar caching module. PerDiS additionally supports transactions, potentially alleviating a lot of effort that would otherwise have to be expended by the distributed application writer.

The techniques for keeping a distributed cache coherent come from Operating System research. Our particular implementation takes its algorithms from ``Memory Coherence in Shared Virtual Memory Systems'' [6] which describes a Distributed Shared Memory (DSM).

Section 2.2.3 describes our Virtual Disk Cache

Section 2 describes our implementation of the different parts of our new distributed system. Section 3 discusses the peformance and usability of our implementation. Section 4 is a discussion and conclusion.


next up previous
Next: Design and Implementation Up: Introduction Previous: Distributed Persistent Systems and
John Leuner
1999-10-13