Lecture 6 Notes

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Unformatted text preview: llenges –  Scale to millions of nodes –  Churn –  Heterogeneity DHTs •  IDs from a flat namespace –  Contrast with hierarchical IP, DNS •  Metaphor: hash table, but distributed •  Interface –  Get(key) –  Put(key, value) •  How? –  Every node supports a single opera)on: Given a key, route messages to node holding key Consistent Hashing •  Map keys to nodes •  nodeid = hash(node ip) •  K mapped to successor(k) •  Successor(k) = node equal to or follows K 7 Consistent Hashing Proper)es •  Designed for node join/leave with minimal churn in key mapping •  K/N keys per node •  K/N keys change hands during join/leave 8 Iden)fier to Node Mapping Example •  •  •  •  •  Node 8 maps [5,8] Node 15 maps [9,15] Node 20 maps [16, 20] … Node 4 maps [59, 4] 4 58 8 15 •  Each node maintains a pointer to its successor 44 20 35 32 Example from Ion Stoica Lookup lookup(37) •  Each node maintains its successor 4 58 •  Route packet (ID, data) to the...
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This note was uploaded on 01/27/2014 for the course COSC 4377 taught by Professor Staff during the Spring '08 term at University of Houston.

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