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https://issues.apache.org/jira/browse/HDFS-7337?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=16007259#comment-16007259
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Lei (Eddy) Xu commented on HDFS-7337:
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Thanks a lot for the new design doc, it looks great, [~Sammi]
bq. For remove policy, one suggestion is the lazy remove. That is, when user
uses the CLI command to remove a policy A, policy A will only be marked as
removed in NN and will not be available to apply to new dir/file any more. But
until next time NN restart, if there is no dir/file using this policy, then
policy A can be deleted permanently from the system.
Do you know what is the overhead of this check when NN restarts? Will it
introduce noticeable slowdown to NN start process?
* Enable policy: while it supports to add / remove policies using CLI, but why
it dose not support to enable / use the policy via CLI? This limitation makes
the user experience not consistent .
* For the configuration keys of codecs, why do we need ".rawcoders" as suffix
for each one?
bq. The order is defined by a list of coder names separated by commas.
Do you mean the implementations of the same algorithm? Btw, is there a
system-wide default codec / configuration to use?
> Configurable and pluggable Erasure Codec and schema
> ---------------------------------------------------
>
> Key: HDFS-7337
> URL: https://issues.apache.org/jira/browse/HDFS-7337
> Project: Hadoop HDFS
> Issue Type: New Feature
> Components: erasure-coding
> Reporter: Zhe Zhang
> Priority: Critical
> Labels: hdfs-ec-3.0-nice-to-have
> Attachments: HDFS-7337-prototype-v1.patch,
> HDFS-7337-prototype-v2.zip, HDFS-7337-prototype-v3.zip,
> PluggableErasureCodec.pdf, PluggableErasureCodec-v2.pdf,
> PluggableErasureCodec-v3.pdf, PluggableErasureCodec v4.pdf
>
>
> According to HDFS-7285 and the design, this considers to support multiple
> Erasure Codecs via pluggable approach. It allows to define and configure
> multiple codec schemas with different coding algorithms and parameters. The
> resultant codec schemas can be utilized and specified via command tool for
> different file folders. While design and implement such pluggable framework,
> it’s also to implement a concrete codec by default (Reed Solomon) to prove
> the framework is useful and workable. Separate JIRA could be opened for the
> RS codec implementation.
> Note HDFS-7353 will focus on the very low level codec API and implementation
> to make concrete vendor libraries transparent to the upper layer. This JIRA
> focuses on high level stuffs that interact with configuration, schema and etc.
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