concept peer in category nosql
This is an excerpt from Manning's book Making Sense of NoSQL.
From a distribution perspective, there are two main models: master-slave and peer-to-peer. Distribution models determine the responsibility for processing data when a request is made.
Understanding the pros and cons of each distribution model is important when you’re looking at a potential big data solution. Peer-to-peer models may be more resilient to failure than master-slave models. Some master-slave distribution models have single points of failure that might impact your system availability, so you might need to take special care when configuring these systems.
Distribution models get to the heart of the question who’s in charge here? There are two ways to answer this question: one node or all nodes. In the master-slave model, one node is in charge (master). When there’s no single node with a special role in taking charge, you have a peer-to-peer distribution model.
Figure 6.7. Master-slave versus peer-to-peer—the panel on the left illustrates a master-slave configuration where all incoming database requests (reads or writes) are sent to a single master node and redistributed from there. The master node is called the NameNode in Hadoop. This node keeps a database of all the other nodes in the cluster and the rules for distributing requests to each node. The panel on the right shows how the peer-to-peer model stores all the information about the cluster on each node in the cluster. If any node crashes, the other nodes can take over and processing can continue.
