| Popis: |
In recent years there has been considerable research on new distributed hash tables (DHTs), improvements on existing DHTs, and DHT-enabled systems. However, little of it focuses on their differences [M. Castro et al., 2002]. To this purpose we introduce a simple modeling framework that allows us to mathematically model the search costs of most classes of DHTs. To illustrate the usefulness of this framework, we examine a class of DHTs, which includes tapestry and pastry, that we call dynamic PRR meshes (DPMs). In particular we examine how planned object duplication (POD) strategies affect the search costs of DPMs that employ them. We introduce 3 new DPMs that employ different POD strategies and compare them with the POD strategies that tapestry and pastry use. Through our model we discover cyclic behaviors in search costs over the number of nodes present in the DPM, the effects of variability in the underlying network and provide comparisons of the performance of all 5 DPMs. |
