org.apache.hadoop.hdfs.server.namenode
Class FSNamesystem.SafeModeInfo

java.lang.Object
  org.apache.hadoop.hdfs.server.namenode.FSNamesystem.SafeModeInfo

Enclosing class:

org.apache.hadoop.hdfs.server.namenode.FSNamesystem

public class FSNamesystem.SafeModeInfo
extends Object

SafeModeInfo contains information related to the safe mode.

An instance of FSNamesystem.SafeModeInfo is created when the name node enters safe mode.

During name node startup FSNamesystem.SafeModeInfo counts the number of safe blocks, those that have at least the minimal number of replicas, and calculates the ratio of safe blocks to the total number of blocks in the system, which is the size of blocks in FSNamesystem.blockManager. When the ratio reaches the threshold it starts the SafeModeMonitor daemon in order to monitor whether the safe mode extension is passed. Then it leaves safe mode and destroys itself.

If safe mode is turned on manually then the number of safe blocks is not tracked because the name node is not intended to leave safe mode automatically in the case.

See Also:

ClientProtocol.setSafeMode(HdfsConstants.SafeModeAction, boolean)

Method Summary

String

toString()

Methods inherited from class java.lang.Object

clone, equals, finalize, getClass, hashCode, notify, notifyAll, wait, wait, wait

Method Detail

toString

public String toString()

Overrides:

toString in class Object