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https://issues.apache.org/jira/browse/HDFS-7680?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel
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Joe Pallas updated HDFS-7680:
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Description:
As described in HDFS-5194, the current support for short circuit reading is
tightly coupled to the default Dataset implementation. Since alternative
implementations of the FsDatasetSpi may use a different short circuit pathway,
there needs to be a way for the client to acquire the right kind of BlockReader.
Reviewing some considerations:
Today, there is only one dataset per datanode (with multiple volumes). Is that
likely to change?
Can there be multiple datanodes local to a client? (definition of "local" might
depend on dataset implementation)
Is it okay to assume that the client and datanode share configuration? More
broadly, how should the client discover the appropriate short-circuit
implementation?
was:
As described in HDFS-5194, the current support for short circuit reading is
tightly coupled to the default Dataset implementation. Since alternative
implementations of the FsDatasetSpi may use a different short circuit pathway,
there needs to be a way for the client to acquire the right kind of BlockReader.
Reviewing some considerations:
Today, there is only one dataset per datanode (with multiple volumes). Is that
likely to change?
Can there be multiple datanodes local to a client?
Is it okay to assume that the client and datanode share configuration? More
broadly, how should the client discover the appropriate short-circuit
implementation?
> Support dataset-specific choice of short circuit implementation
> ---------------------------------------------------------------
>
> Key: HDFS-7680
> URL: https://issues.apache.org/jira/browse/HDFS-7680
> Project: Hadoop HDFS
> Issue Type: Sub-task
> Components: datanode, dfsclient, hdfs-client
> Affects Versions: 3.0.0
> Reporter: Joe Pallas
> Assignee: Joe Pallas
>
> As described in HDFS-5194, the current support for short circuit reading is
> tightly coupled to the default Dataset implementation. Since alternative
> implementations of the FsDatasetSpi may use a different short circuit
> pathway, there needs to be a way for the client to acquire the right kind of
> BlockReader.
> Reviewing some considerations:
> Today, there is only one dataset per datanode (with multiple volumes). Is
> that likely to change?
> Can there be multiple datanodes local to a client? (definition of "local"
> might depend on dataset implementation)
> Is it okay to assume that the client and datanode share configuration? More
> broadly, how should the client discover the appropriate short-circuit
> implementation?
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