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https://issues.apache.org/jira/browse/HDFS-16521?focusedWorklogId=755010&page=com.atlassian.jira.plugin.system.issuetabpanels:worklog-tabpanel#worklog-755010
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ASF GitHub Bot logged work on HDFS-16521:
-----------------------------------------
Author: ASF GitHub Bot
Created on: 10/Apr/22 09:49
Start Date: 10/Apr/22 09:49
Worklog Time Spent: 10m
Work Description: virajjasani commented on PR #4107:
URL: https://github.com/apache/hadoop/pull/4107#issuecomment-1094233257
To provide more insights,
[FanOutOneBlockAsyncDFSOutput](https://github.com/apache/hbase/blob/master/hbase-asyncfs/src/main/java/org/apache/hadoop/hbase/io/asyncfs/FanOutOneBlockAsyncDFSOutput.java)
in HBase currently has to rely on it's own way of marking and excluding slow
nodes while 1) creating pipelines and 2) handling ack, based on factors like
the data length of the packet, processing time with last ack timestamp, whether
flush to replicas is finished etc. If it can utilize slownode API from HDFS to
exclude nodes appropriately while writing block, a lot of it's own post-ack
computation of slow nodes can be _saved_ or _improved_ or based on further
experiment, we could find _better solution_ to manage slow node detection logic
both in HDFS and HBase. However, in order to collect more data points and run
more POC around this area, at least we should expect HDFS to provide API for
downstreamers to efficiently utilize slownode info for such critical
low-latency use-case (like writing WALs).
cc @jojochuang @saintstack
Issue Time Tracking
-------------------
Worklog Id: (was: 755010)
Time Spent: 3h (was: 2h 50m)
> DFS API to retrieve slow datanodes
> ----------------------------------
>
> Key: HDFS-16521
> URL: https://issues.apache.org/jira/browse/HDFS-16521
> Project: Hadoop HDFS
> Issue Type: New Feature
> Reporter: Viraj Jasani
> Assignee: Viraj Jasani
> Priority: Major
> Labels: pull-request-available
> Time Spent: 3h
> Remaining Estimate: 0h
>
> Providing DFS API to retrieve slow nodes would help add an additional option
> to "dfsadmin -report" that lists slow datanodes info for operators to take a
> look, specifically useful filter for larger clusters.
> The other purpose of such API is for HDFS downstreamers without direct access
> to namenode http port (only rpc port accessible) to retrieve slownodes.
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