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https://issues.apache.org/jira/browse/HDFS-17868?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=18057152#comment-18057152
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ASF GitHub Bot commented on HDFS-17868:
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hadoop-yetus commented on PR #8159:
URL: https://github.com/apache/hadoop/pull/8159#issuecomment-3867193179
:broken_heart: **-1 overall**
| Vote | Subsystem | Runtime | Logfile | Comment |
|:----:|----------:|--------:|:--------:|:-------:|
| +0 :ok: | reexec | 0m 0s | | Docker mode activated. |
| -1 :x: | patch | 0m 29s | |
https://github.com/apache/hadoop/pull/8159 does not apply to trunk. Rebase
required? Wrong Branch? See
https://cwiki.apache.org/confluence/display/HADOOP/How+To+Contribute for help.
|
| Subsystem | Report/Notes |
|----------:|:-------------|
| Console output |
https://ci-hadoop.apache.org/job/hadoop-multibranch/job/PR-8159/6/console |
| versions | git=2.34.1 |
| Powered by | Apache Yetus 0.14.1 https://yetus.apache.org |
This message was automatically generated.
> introduce BlockPlacementPolicyCrossDC for multi datacenter stretched hdfs
> cluster
> ---------------------------------------------------------------------------------
>
> Key: HDFS-17868
> URL: https://issues.apache.org/jira/browse/HDFS-17868
> Project: Hadoop HDFS
> Issue Type: New Feature
> Components: block placement
> Reporter: YUBI LEE
> Priority: Major
> Labels: pull-request-available
>
> I was inspired by the ideas presented in
> https://dan.naver.com/25/sessions/692 and
> https://www.youtube.com/watch?v=1h4k_Dbt0t8 and implemented a new block
> placement policy called BlockPlacementPolicyCrossDC.
> Thanks to [~acedia28] for the original ideas. It would be great if
> [~acedia28] could share an improved or more mature version of this block
> placement policy.
> This implementation introduces the following configuration options
> (default values are shown in parentheses):
> {code}
> dfs.block.replicator.cross.dc.async.enabled (false)
> dfs.block.replicator.cross.dc.preferred.datacenter
> dfs.block.replicator.cross.dc.bandwidth.limit.mb (5120)
> dfs.block.replicator.cross.dc.bandwidth.refill.period.sec (1)
> dfs.block.replicator.cross.dc.sync.paths
> dfs.block.replicator.cross.dc.limited.sync.paths
> {code}
> BlockPlacementPolicyCrossDC assumes that DataNodes are registered with
> two-level rack topology information, such as /dc1/rack1 or /dc2/rack2.
> Based on the ideas from the session mentioned above, this policy supports
> three different HDFS block write modes:
> 1. Synchronous write
> The standard HDFS behavior, where block replicas are synchronously written to
> all target DataNodes.
> 2. Limited synchronous write
> Uses bucket4j to control cross-datacenter traffic.
> Writes below the configured threshold are performed synchronously, while
> writes exceeding the threshold fall back to asynchronous replication.
> 3. Asynchronous write
> The client is initially given only DataNode candidates located in the same
> datacenter.
> With asynchronous write, the hdfs client app will not suffer from write
> latency caused by cross-datacenter communication.
> Any under-replicas are created later through background HDFS replication to
> other datacenters.
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