Traditionally,
several problems constrain design of DHTs. e.g. Link capacity of node, physical
distance of nodes, network congestion/packet loss. This paper introduces a
distributed hash table aimed at lowering latency and improving throughout. This
paper addresses several important issues concerning the DHT's design.
Firstly, for
latency reduction, iterative/recursive lookups are compared. Iterative lookup
query to each successive node in the path, although it can detect node
failures, it has to wait for response before next operation. In comparison,
recursive lookup takes fewer queries and less network flow - it forward query
to the next node. Secondly, selection of proximity neighbor is also important
to reduce latency, ID-space range is defined to proximity detection. Lastly,
latency is related with storage policies: erasure-coding and replication,
latency is proportional to l/m where l is number of fragments and m is the
number required to reconstruct the block.
As for high throughput, the biggest difficulty is that data is spread over a large set of servers. This paper introduces an alternative transport protocol STP (Striped Transport Protocol), it can transmit data directly to other nodes in a single instance, which has higher throughput and lower latency than TCP.
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