Package org.apache.hadoop.hdfs.server.datanode

Class DiskBalancer

java.lang.Object

org.apache.hadoop.hdfs.server.datanode.DiskBalancer

@Private
public class DiskBalancer
extends Object

Worker class for Disk Balancer.

Here is the high level logic executed by this class. Users can submit disk balancing plans using submitPlan calls. After a set of sanity checks the plan is admitted and put into workMap.

The executePlan launches a thread that picks up work from workMap and hands it over to the BlockMover#copyBlocks function.

Constraints :

Only one plan can be executing in a datanode at any given time. This is ensured by checking the future handle of the worker thread in submitPlan.

Nested Class Summary

Nested Classes

Modifier and Type	Class	Description
static interface	DiskBalancer.BlockMover	BlockMover supports moving blocks across Volumes.
static class	DiskBalancer.DiskBalancerMover	Actual DataMover class for DiskBalancer.
static class	DiskBalancer.VolumePair	Holds source and dest volumes UUIDs and their BasePaths that disk balancer will be operating against.

Field Summary

Fields

Modifier and Type	Field	Description
static final org.slf4j.Logger	LOG

Constructor Summary

Constructors

Constructor	Description
DiskBalancer(String dataNodeUUID, org.apache.hadoop.conf.Configuration conf, DiskBalancer.BlockMover blockMover)	Constructs a Disk Balancer object.

Method Summary

Modifier and Type	Method	Description
void	cancelPlan(String planID)	Cancels a running plan.
long	getBandwidth()	Returns the current bandwidth.
long	getPlanValidityInterval()	Gets maximum amount of time disk balancer plan is valid.
long	getPlanValidityIntervalInConfig()	Gets maximum amount of time disk balancer plan is valid in config.
String	getVolumeNames()	Returns a volume ID to Volume base path map.
boolean	isDiskBalancerEnabled()	Returns the value indicating if diskBalancer is enabled.
org.apache.hadoop.hdfs.server.datanode.DiskBalancerWorkStatus	queryWorkStatus()	Returns the current work status of a previously submitted Plan.
void	setDiskBalancerEnabled(boolean diskBalancerEnabled)	Sets Disk balancer is to enable or not to enable.
void	setPlanValidityInterval(long planValidityInterval)	Sets maximum amount of time disk balancer plan is valid.
void	shutdown()	Shutdown disk balancer services.
void	submitPlan(String planId, long planVersion, String planFileName, String planData, boolean force)	Takes a client submitted plan and converts into a set of work items that can be executed by the blockMover.

Methods inherited from class java.lang.Object

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

Field Details

LOG

@VisibleForTesting
public static final org.slf4j.Logger LOG

Constructor Details

DiskBalancer

public DiskBalancer(String dataNodeUUID,
 org.apache.hadoop.conf.Configuration conf,
 DiskBalancer.BlockMover blockMover)

Constructs a Disk Balancer object. This object takes care of reading a NodePlan and executing it against a set of volumes.

Parameters:

dataNodeUUID - - Data node UUID

conf - - Hdfs Config

blockMover - - Object that supports moving blocks.

Method Details

shutdown

public void shutdown()

Shutdown disk balancer services.

submitPlan

public void submitPlan(String planId,
 long planVersion,
 String planFileName,
 String planData,
 boolean force)
                throws DiskBalancerException

Takes a client submitted plan and converts into a set of work items that can be executed by the blockMover.

Parameters:

planId - - A SHA-1 of the plan string

planVersion - - version of the plan string - for future use.

planFileName - - Plan file name

planData - - Plan data in json format

force - - Skip some validations and execute the plan file.

Throws:

DiskBalancerException

queryWorkStatus

public org.apache.hadoop.hdfs.server.datanode.DiskBalancerWorkStatus queryWorkStatus()
                                                                              throws DiskBalancerException

Returns the current work status of a previously submitted Plan.

Returns:

DiskBalancerWorkStatus.

Throws:

DiskBalancerException

cancelPlan

public void cancelPlan(String planID)
                throws DiskBalancerException

Cancels a running plan.

Parameters:

planID - - Hash of the plan to cancel.

Throws:

DiskBalancerException

getVolumeNames

public String getVolumeNames()
                      throws DiskBalancerException

Returns a volume ID to Volume base path map.

Returns:

Json string of the volume map.

Throws:

DiskBalancerException

getBandwidth

public long getBandwidth()
                  throws DiskBalancerException

Returns the current bandwidth.

Returns:

string representation of bandwidth.

Throws:

DiskBalancerException

setDiskBalancerEnabled

public void setDiskBalancerEnabled(boolean diskBalancerEnabled)

Sets Disk balancer is to enable or not to enable.

Parameters:

diskBalancerEnabled - true, enable diskBalancer, otherwise false to disable it.

isDiskBalancerEnabled

@VisibleForTesting
public boolean isDiskBalancerEnabled()

Returns the value indicating if diskBalancer is enabled.

Returns:

boolean.

setPlanValidityInterval

public void setPlanValidityInterval(long planValidityInterval)

Sets maximum amount of time disk balancer plan is valid.

Parameters:

planValidityInterval - - maximum amount of time in the unit of milliseconds.

getPlanValidityInterval

@VisibleForTesting
public long getPlanValidityInterval()

Gets maximum amount of time disk balancer plan is valid.

Returns:

the maximum amount of time in milliseconds.

getPlanValidityIntervalInConfig

@VisibleForTesting
public long getPlanValidityIntervalInConfig()

Gets maximum amount of time disk balancer plan is valid in config.

Returns:

the maximum amount of time in milliseconds.