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Zhe Zhang commented on HDFS-8131: --------------------------------- {{AvailableSpaceBlockPlacementPolicy}} is very useful for large production clusters, many of which are still running 2.6/2.7. So if there are no objections I plan to backport this to branch-2.7. Will wait until end of Wednesday. We are still discussing under HDFS-10967 whether to merge {{AvailableSpaceBlockPlacementPolicy}} into the default BPP. But I think whatever we decide, can be done on top of this one. > Implement a space balanced block placement policy > ------------------------------------------------- > > Key: HDFS-8131 > URL: https://issues.apache.org/jira/browse/HDFS-8131 > Project: Hadoop HDFS > Issue Type: Improvement > Components: namenode > Affects Versions: 3.0.0-alpha1 > Reporter: Liu Shaohui > Assignee: Liu Shaohui > Priority: Minor > Labels: BlockPlacementPolicy > Fix For: 2.8.0, 3.0.0-alpha1 > > Attachments: HDFS-8131-v1.diff, HDFS-8131-v2.diff, HDFS-8131-v3.diff, > HDFS-8131.004.patch, HDFS-8131.005.patch, HDFS-8131.006.patch, balanced.png > > > The default block placement policy will choose datanodes for new blocks > randomly, which will result in unbalanced space used percent among datanodes > after an cluster expansion. The old datanodes always are in high used percent > of space and new added ones are in low percent. > Through we can used the external balance tool to balance the space used rate, > it will cost extra network IO and it's not easy to control the balance speed. > An easy solution is to implement an balanced block placement policy which > will choose low used percent datanodes for new blocks with a little high > possibility. In a not long term, the used percent of datanodes will trend to > be balanced. > Suggestions and discussions are welcomed. Thanks -- This message was sent by Atlassian JIRA (v6.3.4#6332) --------------------------------------------------------------------- To unsubscribe, e-mail: hdfs-issues-unsubscr...@hadoop.apache.org For additional commands, e-mail: hdfs-issues-h...@hadoop.apache.org