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https://issues.apache.org/jira/browse/HDFS-12682?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=16224526#comment-16224526
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Kai Zheng commented on HDFS-12682:
----------------------------------

Thanks for the work and discussions here. I thought the smell of this issue 
indicated we should unify all the EC policies for better and easier 
maintenance. Is it possible or doable? Not sure about its impact though. Thanks.

> ECAdmin -listPolicies will always show SystemErasureCodingPolicies state as 
> DISABLED
> ------------------------------------------------------------------------------------
>
>                 Key: HDFS-12682
>                 URL: https://issues.apache.org/jira/browse/HDFS-12682
>             Project: Hadoop HDFS
>          Issue Type: Bug
>          Components: erasure-coding
>            Reporter: Xiao Chen
>            Assignee: Xiao Chen
>            Priority: Blocker
>              Labels: hdfs-ec-3.0-must-do
>         Attachments: HDFS-12682.01.patch, HDFS-12682.02.patch, 
> HDFS-12682.03.patch
>
>
> On a real cluster, {{hdfs ec -listPolicies}} will always show policy state as 
> DISABLED.
> {noformat}
> [hdfs@nightly6x-1 root]$ hdfs ec -listPolicies
> Erasure Coding Policies:
> ErasureCodingPolicy=[Name=RS-10-4-1024k, Schema=[ECSchema=[Codec=rs, 
> numDataUnits=10, numParityUnits=4]], CellSize=1048576, Id=5, State=DISABLED]
> ErasureCodingPolicy=[Name=RS-3-2-1024k, Schema=[ECSchema=[Codec=rs, 
> numDataUnits=3, numParityUnits=2]], CellSize=1048576, Id=2, State=DISABLED]
> ErasureCodingPolicy=[Name=RS-6-3-1024k, Schema=[ECSchema=[Codec=rs, 
> numDataUnits=6, numParityUnits=3]], CellSize=1048576, Id=1, State=DISABLED]
> ErasureCodingPolicy=[Name=RS-LEGACY-6-3-1024k, 
> Schema=[ECSchema=[Codec=rs-legacy, numDataUnits=6, numParityUnits=3]], 
> CellSize=1048576, Id=3, State=DISABLED]
> ErasureCodingPolicy=[Name=XOR-2-1-1024k, Schema=[ECSchema=[Codec=xor, 
> numDataUnits=2, numParityUnits=1]], CellSize=1048576, Id=4, State=DISABLED]
> [hdfs@nightly6x-1 root]$ hdfs ec -getPolicy -path /ecec
> XOR-2-1-1024k
> {noformat}
> This is because when [deserializing 
> protobuf|https://github.com/apache/hadoop/blob/branch-3.0.0-beta1/hadoop-hdfs-project/hadoop-hdfs-client/src/main/java/org/apache/hadoop/hdfs/protocolPB/PBHelperClient.java#L2942],
>  the static instance of [SystemErasureCodingPolicies 
> class|https://github.com/apache/hadoop/blob/branch-3.0.0-beta1/hadoop-hdfs-project/hadoop-hdfs-client/src/main/java/org/apache/hadoop/hdfs/protocol/SystemErasureCodingPolicies.java#L101]
>  is first checked, and always returns the cached policy objects, which are 
> created by default with state=DISABLED.
> All the existing unit tests pass, because that static instance that the 
> client (e.g. ECAdmin) reads in unit test is updated by NN. :)



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