[elasticsearch] node master/data ....
Elastic/Elasticsearch 2014. 1. 14. 17:34참고글 : http://stackoverflow.com/questions/15019821/what-differents-between-master-node-gateway-and-other-node-gateway-in-elasticsea
참고 하시라고 올려 봅니다.
[원문]
The master node is the same as any other node in the cluster, except that it has been elected to be the master.
It is responsible for coordinating any cluster-wide changes, such as as the addition or removal of a node, creation, deletion or change of state (ie open/close) of an index, and the allocation of shards to nodes. When any of these changes occur, the "cluster state" is updated by the master and published to all other nodes in the cluster. It is the only node that may publish a new cluster state.
The tasks that a master performs are lightweight. Any tasks that deal with data (eg indexing, searching etc) do not need to involve the master. If you choose to run the master as a non-data node (ie a node that acts as master and as a router, but doesn't contain any data) then the master can run happily on a smallish box.
A node is allowed to become a master if it is marked as "master eligible" (which all nodes are by default). If the current master goes down, a new master will be elected by the cluster.
An important configuration option in your cluster is minimum_master_nodes.
This specifies the number of "master eligible" nodes that a node must
be able to see in order to be part of a cluster. Its purpose is to
avoid "split brain" ie having the cluster separate into two clusters,
both of which think that they are functioning correctly.
For instance, if you have 3 nodes, all of which are master eligible, and set minimum_master_nodes
to 1, then if the third node is separated from the other two it, it
still sees one master-eligible node (itself) and thinks that it can form
a cluster by itself.
Instead, set minimum_master_nodes to 2 in this case
(number of nodes / 2 + 1), then if the third node separates, it won't
see enough master nodes, and thus won't form a cluster by itself. It
will keep trying to join the original cluster.
While Elasticsearch tries very hard to choose the correct defaults, minimum_master_nodes
is impossible to guess, as it has no way of knowing how many nodes you
intend to run. This is something you must configure yourself.
[구글 번역]