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https://issues.apache.org/jira/browse/HDFS-7859?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=16146892#comment-16146892
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SammiChen commented on HDFS-7859:
---------------------------------
[~eddyxu] mentioned upgrade and downgrade, it's a good question. Not only user
defined ec policy, but also built-in ec policy will face this issue. The major
problem is if a codec is no longer supported after upgrade or downgrade, how
to handle these type of ec policies in the new cluster, also how to handle the
files/directories which used these no long supported files? I tend to keep
these ec policies in {{ErasureCodingPolicyManager}}, while mark it as obsolete,
and also load these files/directories into the namespace so that user can go
through the tree structures(read file cannot be supported). I will do some
experiment to see if it works.
Any other suggestions are welcome. [~andrew.wang], [~drankye], [~eddyxu]
> Erasure Coding: Persist erasure coding policies in NameNode
> -----------------------------------------------------------
>
> Key: HDFS-7859
> URL: https://issues.apache.org/jira/browse/HDFS-7859
> Project: Hadoop HDFS
> Issue Type: Sub-task
> Reporter: Kai Zheng
> Assignee: SammiChen
> Attachments: HDFS-7859.001.patch, HDFS-7859.002.patch,
> HDFS-7859.004.patch, HDFS-7859.005.patch, HDFS-7859.006.patch,
> HDFS-7859.007.patch, HDFS-7859.008.patch, HDFS-7859.009.patch,
> HDFS-7859.010.patch, HDFS-7859.011.patch, HDFS-7859-HDFS-7285.002.patch,
> HDFS-7859-HDFS-7285.002.patch, HDFS-7859-HDFS-7285.003.patch
>
>
> In meetup discussion with [~zhz] and [~jingzhao], it's suggested that we
> persist EC schemas in NameNode centrally and reliably, so that EC zones can
> reference them by name efficiently.
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