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Nathan Roberts commented on HDFS-2825: -------------------------------------- [~tlipcon] - It might help. I'm a little concerned about the additional round trip and how we might enable it globally for an entire cluster. We'll be running some experiments with a global config for the block placement policy, and then go from there. > Add test hook to turn off the writer preferring its local DN > ------------------------------------------------------------ > > Key: HDFS-2825 > URL: https://issues.apache.org/jira/browse/HDFS-2825 > Project: Hadoop HDFS > Issue Type: Improvement > Components: namenode > Affects Versions: 0.23.0 > Reporter: Todd Lipcon > Assignee: Todd Lipcon > Priority: Minor > Fix For: 0.24.0, 0.23.1 > > Attachments: hdfs-2825.txt, hdfs-2825.txt > > > Currently, the default block placement policy always places the first replica > in the pipeline on the local node if there is a valid DN running there. In > some network designs, within-rack bandwidth is never constrained so this > doesn't give much of an advantage. It would also be really useful to disable > this for MiniDFSCluster tests, since currently if you start a multi-DN > cluster and write with replication level 1, all of the replicas go to the > same DN. > _[per discussion below, this was changed to not add a config, but only to add > a hook for testing]_ -- This message was sent by Atlassian JIRA (v6.3.4#6332)