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Kihwal Lee commented on HDFS-7967: ---------------------------------- [~djp], the progress is stalled because the replica triplet structure was changed fundamentally in trunk. We cannot make an equivalent change in trunk. However, I think this should not block 2.8.2 release, as this is not a regression and HDFS-11384 should also mitigate this. > Reduce the performance impact of the balancer > --------------------------------------------- > > Key: HDFS-7967 > URL: https://issues.apache.org/jira/browse/HDFS-7967 > Project: Hadoop HDFS > Issue Type: Sub-task > Components: namenode > Affects Versions: 2.0.0-alpha > Reporter: Daryn Sharp > Assignee: Daryn Sharp > Priority: Critical > Attachments: HDFS-7967.branch-2.001.patch, > HDFS-7967.branch-2.002.patch, HDFS-7967.branch-2-1.patch, > HDFS-7967.branch-2.8.001.patch, HDFS-7967.branch-2.8.002.patch, > HDFS-7967.branch-2.8.003.patch, HDFS-7967.branch-2.8-1.patch, > HDFS-7967-branch-2.8.patch, HDFS-7967-branch-2.patch > > > The balancer needs to query for blocks to move from overly full DNs. The > block lookup is extremely inefficient. An iterator of the node's blocks is > created from the iterators of its storages' blocks. A random number is > chosen corresponding to how many blocks will be skipped via the iterator. > Each skip requires costly scanning of triplets. > The current design also only considers node imbalances while ignoring > imbalances within the nodes's storages. A more efficient and intelligent > design may eliminate the costly skipping of blocks via round-robin selection > of blocks from the storages based on remaining capacity. -- This message was sent by Atlassian JIRA (v6.4.14#64029) --------------------------------------------------------------------- To unsubscribe, e-mail: hdfs-issues-unsubscr...@hadoop.apache.org For additional commands, e-mail: hdfs-issues-h...@hadoop.apache.org