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

Class AvailableSpaceVolumeChoosingPolicy<V extends FsVolumeSpi>

java.lang.Object

org.apache.hadoop.hdfs.server.datanode.fsdataset.AvailableSpaceVolumeChoosingPolicy<V>

All Implemented Interfaces:

org.apache.hadoop.conf.Configurable, VolumeChoosingPolicy<V>

public class AvailableSpaceVolumeChoosingPolicy<V extends FsVolumeSpi>
extends java.lang.Object
implements VolumeChoosingPolicy<V>, org.apache.hadoop.conf.Configurable

A DN volume choosing policy which takes into account the amount of free space on each of the available volumes when considering where to assign a new replica allocation. By default this policy prefers assigning replicas to those volumes with more available free space, so as to over time balance the available space of all the volumes within a DN. Use fine-grained locks to enable choosing volumes of different storage types concurrently.

Constructor Summary

Constructors

Constructor	Description
AvailableSpaceVolumeChoosingPolicy()

Method Summary

Modifier and Type	Method	Description
V	chooseVolume(java.util.List<V> volumes, long replicaSize, java.lang.String storageId)	Choose a volume to place a replica, given a list of volumes and the replica size sought for storage.
org.apache.hadoop.conf.Configuration	getConf()
void	setConf(org.apache.hadoop.conf.Configuration conf)

Methods inherited from class java.lang.Object

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

Constructor Detail

AvailableSpaceVolumeChoosingPolicy

public AvailableSpaceVolumeChoosingPolicy()

Method Detail

setConf

public void setConf(org.apache.hadoop.conf.Configuration conf)

Specified by:

setConf in interface org.apache.hadoop.conf.Configurable

getConf

public org.apache.hadoop.conf.Configuration getConf()

Specified by:

getConf in interface org.apache.hadoop.conf.Configurable

chooseVolume

public V chooseVolume(java.util.List<V> volumes,
                      long replicaSize,
                      java.lang.String storageId)
               throws java.io.IOException

Description copied from interface: VolumeChoosingPolicy

Choose a volume to place a replica, given a list of volumes and the replica size sought for storage. The caller should synchronize access to the list of volumes.

Specified by:

chooseVolume in interface VolumeChoosingPolicy<V extends FsVolumeSpi>

Parameters:

volumes - - a list of available volumes.

replicaSize - - the size of the replica for which a volume is sought.

storageId - - the storage id of the Volume nominated by the namenode. This can usually be ignored by the VolumeChoosingPolicy.

Returns:

the chosen volume.

Throws:

java.io.IOException - when disks are unavailable or are full.