org.apache.hadoop.hdfs.protocol.datatransfer

Enum ReplaceDatanodeOnFailure

java.lang.Object

java.lang.Enum<ReplaceDatanodeOnFailure>

org.apache.hadoop.hdfs.protocol.datatransfer.ReplaceDatanodeOnFailure

All Implemented Interfaces:

Serializable, Comparable<ReplaceDatanodeOnFailure>

@InterfaceAudience.Private
@InterfaceStability.Evolving
public enum ReplaceDatanodeOnFailure
extends Enum<ReplaceDatanodeOnFailure>

The setting of replace-datanode-on-failure feature.

Enum Constant Summary

Enum Constants

Enum Constant and Description
ALWAYS Always add a new datanode when an existing datanode is removed.
DEFAULT DEFAULT policy: Let r be the replication number.
DISABLE The feature is disabled in the entire site.
NEVER Never add a new datanode.

Method Summary

Methods

Modifier and Type	Method and Description
void	checkEnabled() Check if the feature is enabled.
static ReplaceDatanodeOnFailure	get(Configuration conf) Get the setting from configuration.
boolean	satisfy(short replication, DatanodeInfo[] existings, boolean isAppend, boolean isHflushed) Is the policy satisfied?
static ReplaceDatanodeOnFailure	valueOf(String name) Returns the enum constant of this type with the specified name.
static ReplaceDatanodeOnFailure[]	values() Returns an array containing the constants of this enum type, in the order they are declared.
void	write(Configuration conf) Write the setting to configuration.

Methods inherited from class java.lang.Enum

clone, compareTo, equals, finalize, getDeclaringClass, hashCode, name, ordinal, toString, valueOf

Methods inherited from class java.lang.Object

getClass, notify, notifyAll, wait, wait, wait

Enum Constant Detail

DISABLE

public static final ReplaceDatanodeOnFailure DISABLE

The feature is disabled in the entire site.

NEVER

public static final ReplaceDatanodeOnFailure NEVER

Never add a new datanode.

DEFAULT

public static final ReplaceDatanodeOnFailure DEFAULT

DEFAULT policy: Let r be the replication number. Let n be the number of existing datanodes. Add a new datanode only if r >= 3 and either (1) floor(r/2) >= n; or (2) r > n and the block is hflushed/appended.

ALWAYS

public static final ReplaceDatanodeOnFailure ALWAYS

Always add a new datanode when an existing datanode is removed.

Method Detail

values

public static ReplaceDatanodeOnFailure[] values()

Returns an array containing the constants of this enum type, in the order they are declared. This method may be used to iterate over the constants as follows:

for (ReplaceDatanodeOnFailure c : ReplaceDatanodeOnFailure.values())
    System.out.println(c);

Returns:

an array containing the constants of this enum type, in the order they are declared

valueOf

public static ReplaceDatanodeOnFailure valueOf(String name)

Returns the enum constant of this type with the specified name. The string must match exactly an identifier used to declare an enum constant in this type. (Extraneous whitespace characters are not permitted.)

Parameters:

name - the name of the enum constant to be returned.

Returns:

the enum constant with the specified name

Throws:

IllegalArgumentException - if this enum type has no constant with the specified name

NullPointerException - if the argument is null

checkEnabled

public void checkEnabled()

Check if the feature is enabled.

satisfy

public boolean satisfy(short replication,
              DatanodeInfo[] existings,
              boolean isAppend,
              boolean isHflushed)

Is the policy satisfied?

get

public static ReplaceDatanodeOnFailure get(Configuration conf)

Get the setting from configuration.

write

public void write(Configuration conf)

Write the setting to configuration.