====== HDFS (HaDoop File System) ======
HDFS is one of utils that included at [[Hadoop]] framework.
  * HDFS knows to handle large file (Ex. 1ptb) and split it to [[Data block|Data blocks]] and distrebute it over [[Cluster]].
  * HDFS has [[wp>Fault tolerance]] - [[HDFS]] replicate same [[Data block]] on X [[Data node|Data nodes]]. X is  [[Replication factor]]
  * HDFS Master / Slaves architecture

===== HDFS Features =====
  * Rack awarness - What happends if entire rack is lost ?
  * Reliable storage
  * High throughput
===== Tools =====
  * [[dfsadmin]]
  * [[fs shell]]
  * Web-UIs

===== Nodes =====
==== Data world ====
  * [[Name node]] - FS Ops, Block Mapping
  * [[Secondary name node]] - Checkpoint Ops
  * [[Data node]] - Block Ops, Replications
==== MapReduce world ====
See: [[MapReduce]]
  * Master: [[Job tracker]] - controller of [[Task tracker|Task trackers]]
  * [[Task tracker]]