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From "Lei (Eddy) Xu (JIRA)" <j...@apache.org>
Subject [jira] [Comment Edited] (HDFS-12482) Provide a configuration to adjust the weight of EC recovery tasks to adjust the speed of recovery
Date Thu, 19 Oct 2017 18:26:00 GMT

    [ https://issues.apache.org/jira/browse/HDFS-12482?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=16211500#comment-16211500
] 

Lei (Eddy) Xu edited comment on HDFS-12482 at 10/19/17 6:25 PM:
----------------------------------------------------------------

Thanks for the reviews, [~andrew.wang]

Updated the patch to add documents.  Empirically, an value between {{(0, 1.0]}} seems can
achieve similar recovery speed and network / cpu overhead between replicated blocks and ec
block recovery _on my testing cluster_. But it highly depends on HW.  I will set this value
to {{0.5}} initially in this patch.

[~xiaochen], [~manojg] mind to give a review?


was (Author: eddyxu):
Thanks for the reviews, [~andrew.wang]

Updated the patch to add documents.  Empirically, an value between {{(0, 1.0]}} seems can
achieve similar recovery speed and network / cpu overhead between replicated blocks and ec
block recovery _on my testing cluster_. But it highly depends on HW.  I will set this value
to {{0.5}} initially in this patch.


> Provide a configuration to adjust the weight of EC recovery tasks to adjust the speed
of recovery
> -------------------------------------------------------------------------------------------------
>
>                 Key: HDFS-12482
>                 URL: https://issues.apache.org/jira/browse/HDFS-12482
>             Project: Hadoop HDFS
>          Issue Type: Improvement
>          Components: erasure-coding
>    Affects Versions: 3.0.0-alpha4
>            Reporter: Lei (Eddy) Xu
>            Assignee: Lei (Eddy) Xu
>            Priority: Minor
>              Labels: hdfs-ec-3.0-nice-to-have
>         Attachments: HDFS-12482.00.patch, HDFS-12482.01.patch
>
>
> The relative speed of EC recovery comparing to 3x replica recovery is a function of (EC
codec, number of sources, NIC speed, and CPU speed, and etc). 
> Currently the EC recovery has a fixed {{xmitsInProgress}} of {{max(# of sources, # of
targets)}} comparing to {{1}} for 3x replica recovery, and NN uses {{xmitsInProgress}} to
decide how much recovery tasks to schedule to the DataNode this we can add a coefficient for
user to tune the weight of EC recovery tasks.



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