Yang Yun created HDFS-15896:
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Summary: Add used percert limitation to
BlockPlacementPolicyDefault for choosing DataNode to write
Key: HDFS-15896
URL: https://issues.apache.org/jira/browse/HDFS-15896
Project: Hadoop HDFS
Issue Type: Improvement
Components: block placement
Environment: {code:java}
{code}
Reporter: Yang Yun
Assignee: Yang Yun
Add used percent limitation to BlockPlacementPolicyDefault for choosing
datanode to write.
The logical is similar with avoid stale node.
Default is disable, the high used percent is 100.0%
{code:java}
public static final String
DFS_NAMENODE_HIGH_USED_DATANODE_FOR_WRITE_PERCENT_KEY =
"dfs.namenode.high-used.datanode.for.wirte.percent";
public static final float
DFS_NAMENODE_HIGH_USED_DATANODE_FOR_WRITE_PERCENT_DEFAULT =
100.0f;{code}
The choosing will try two times, if the first failed for high used datanode, it
will try again without high used limitation.
Also add a high used ratio, when the percentage of high used datanodes
reaches this ratio, allow writing to high used nodes to prevent hotspots.
{code:java}
public static final String
DFS_NAMENODE_HIGH_USED_DATANODE_FOR_WRITE_RATIO_KEY =
"dfs.namenode.high-used.datanode.for.wirte.ratio";
public static final float
DFS_NAMENODE_HIGH_USED_DATANODE_FOR_WRITE_RATIO_DEFAULT = 0.6f;{code}
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