Package org.apache.hadoop.hdfs

A distributed implementation of FileSystem. This is loosely modelled after Google's GFS.

The most important difference is that unlike GFS, Hadoop DFS files have strictly one writer at any one time. Bytes are always appended to the end of the writer's stream. There is no notion of "record appends" or "mutations" that are then checked or reordered. Writers simply emit a byte stream. That byte stream is guaranteed to be stored in the order written.

Class Summary

Class	Description
DeprecatedUTF8	A simple wrapper around UTF8.
DFSConfigKeys	This class contains constants for configuration keys and default values used in hdfs.
DFSUtil
DFSUtil.ConfiguredNNAddress	Represent one of the NameNodes configured in the cluster.
DFSUtil.ServiceComparator	Comparator for sorting DataNodeInfo[] based on decommissioned and entering_maintenance states.
DFSUtil.StaleAndSlowComparator	Comparator for sorting DataNodeInfo[] based on slow, stale, entering_maintenance, decommissioning and decommissioned states.
HAUtil
HdfsDtFetcher	DtFetcher is an interface which permits the abstraction and separation of delegation token fetch implementaions across different packages and compilation units.
HDFSPolicyProvider	PolicyProvider for HDFS protocols.
NameNodeProxies	Create proxy objects to communicate with a remote NN.
SWebHdfsDtFetcher	DtFetcher for SWebHdfsFileSystem using the base class HdfsDtFetcher impl.
WebHdfsDtFetcher	DtFetcher for WebHdfsFileSystem using the base class HdfsDtFetcher impl.