Package org.apache.hadoop.dfs

A distributed implementation of FileSystem.

See:
          Description

Interface Summary
FSConstants Some handy constants
 

Class Summary
DataNode DataNode is a class (and program) that stores a set of blocks for a DFS deployment.
DatanodeID DatanodeID is composed of the data node name (hostname:portNumber) and the data storage ID, which it currently represents.
DatanodeInfo DatanodeInfo represents the status of a DataNode.
DataNodeReport Deprecated. Use DatanodeInfo instead.
DFSck This class provides rudimentary checking of DFS volumes for errors and sub-optimal conditions.
DFSck.Result Result of checking, plus overall DFS statistics.
DFSShell This class provides some DFS administrative access.
DistributedFileSystem Implementation of the abstract FileSystem for the DFS system.
JspHelper  
NameNode NameNode serves as both directory namespace manager and "inode table" for the Hadoop DFS.
StreamFile  
 

Exception Summary
AlreadyBeingCreatedException The exception that happens when you ask to create a file that already is being created, but is not closed yet.
LeaseExpiredException The lease that was being used to create this file has expired.
NotReplicatedYetException The file has not finished being written to enough datanodes yet.
 

Package org.apache.hadoop.dfs Description

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.



Copyright © 2006 The Apache Software Foundation