[jira] [Created] (HDFS-9083) Replication violates block placement policy.

["Rushabh S Shah (JIRA)" <ji...@apache.org>]

Rushabh S Shah created HDFS-9083:
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             Summary: Replication violates block placement policy.
                 Key: HDFS-9083
                 URL: https://issues.apache.org/jira/browse/HDFS-9083
             Project: Hadoop HDFS
          Issue Type: Bug
          Components: HDFS, namenode
    Affects Versions: 2.6.0
            Reporter: Rushabh S Shah


Recently we are noticing many cases in which all the replica of the block are residing on the same rack.
During the block creation, the block placement policy was honored.
But after node failure event in some specific manner, the block ends up in such state.

On investigating more I found out that BlockManager#blockHasEnoughRacks is dependent on the config (net.topology.script.file.name)
{noformat}
 if (!this.shouldCheckForEnoughRacks) {
      return true;
    }
{noformat}
We specify DNSToSwitchMapping implementation (our own custom implementation) via net.topology.node.switch.mapping.impl and no longer use net.topology.script.file.name config.




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