DistOS 2014W Lecture 19

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 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