DistOS 2014W Lecture 19

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Dynamo

  • Key value-store.
  • Build a distributed storage system:
  • Scale
  • Simple: key-value
  • Highly available
  • Guarantee Service Level Agreements (SLA).
  • high concurrent.
  • no dynamic routing.
  • 0-hop DHT: means it is doe not have information when deliver packet from node to another , it has direct link to the destination
  • Dynamo sacrifices consistency under certain failure scenarios.
  • it has partition algorithm.
  • Consistent hashing: the output range of a hash function is treated as a fixed circular space or “ring”.
  • Key is linear and the nodes is partition.
  • ”Virtual Nodes”: Each node can be responsible for more than one virtual node.
  • Each data item is replicated at N hosts.
  • “preference list”: The list of nodes that is responsible for storing a particular key.
  • Sacrifice strong consistency for availability
  • it work with 100 servers,it is not more big.

Bigtable

  • BigTable is a distributed storage system for managing structured data.
  • Designed to scale to a very large size
  • it stores the column together ,the raw is web pages and the column is the contents.
  • Each pages have incoming links
  • A BigTable is a sparse, distributed persistent multi-dimensional sorted map.
  • it have a many columns and it is look as table.
  • Each raw has arbitrary column.
  • It is multi daimination map.
  • An SSTable provides a persistent,ordered immutable map from keys to values, where both keys and values are arbitrary byte strings.
  • Large tables broken into tablets at row boundaries and each raw Tablet holds contiguous range of rows.