Package org.apache.hadoop.ha

Class FailoverController

java.lang.Object

org.apache.hadoop.ha.FailoverController

@Private
@Evolving
public class FailoverController
extends Object

The FailOverController is responsible for electing an active service on startup or when the current active is changing (eg due to failure), monitoring the health of a service, and performing a fail-over when a new active service is either manually selected by a user or elected.

Constructor Summary

Constructors

Constructor	Description
FailoverController(Configuration conf, HAServiceProtocol.RequestSource source)

Method Summary

Modifier and Type	Method	Description
void	failover(HAServiceTarget fromSvc, HAServiceTarget toSvc, boolean forceFence, boolean forceActive)	Failover from service 1 to service 2.

Methods inherited from class java.lang.Object

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

Constructor Details

FailoverController

public FailoverController(Configuration conf,
 HAServiceProtocol.RequestSource source)

Method Details

failover

public void failover(HAServiceTarget fromSvc,
 HAServiceTarget toSvc,
 boolean forceFence,
 boolean forceActive)
              throws FailoverFailedException

Failover from service 1 to service 2. If the failover fails then try to failback.

Parameters:

fromSvc - currently active service

toSvc - service to make active

forceFence - to fence fromSvc even if not strictly necessary

forceActive - try to make toSvc active even if it is not ready

Throws:

FailoverFailedException - if the failover fails