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

Interface VolumeChoosingPolicy<V extends FsVolumeSpi>

All Known Implementing Classes:

AvailableSpaceVolumeChoosingPolicy, RoundRobinVolumeChoosingPolicy

@Private
public interface VolumeChoosingPolicy<V extends FsVolumeSpi>

This interface specifies the policy for choosing volumes to store replicas.

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.

Method Detail

chooseVolume

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

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.

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.