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https://issues.apache.org/jira/browse/HDFS-3672?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=13433788#comment-13433788
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Andrew Wang commented on HDFS-3672:
-----------------------------------
Thanks everyone for all your input! Here's another spin of the patch. Big
things:
* I renamed the Disk* classes to BlockStorageLocation and VolumeId, and tried
to update all the javadoc/comments.
* I split out most of the DFSClient code into a new BlockStorageLocationUtil
class, which is ~300 lines of static methods. I pulled apart one of the long
methods. Doing this for the other long method would arguably be messier, so I
left it.
* Added the DN-side config option. If any of the DNs throws an
UnsupportedOperationException, it's bubbled up to the client (thus failing the
entire call). The client-side code also checks for the same DN config option,
so you need to enable it in both the client and DN for this to do anything.
* Bumped the DN handler count to 10.
I think Suresh's other more minor comments are also addressed.
> Expose disk-location information for blocks to enable better scheduling
> -----------------------------------------------------------------------
>
> Key: HDFS-3672
> URL: https://issues.apache.org/jira/browse/HDFS-3672
> Project: Hadoop HDFS
> Issue Type: Improvement
> Affects Versions: 2.0.0-alpha
> Reporter: Andrew Wang
> Assignee: Andrew Wang
> Attachments: design-doc-v1.pdf, design-doc-v2.pdf, hdfs-3672-1.patch,
> hdfs-3672-2.patch, hdfs-3672-3.patch, hdfs-3672-4.patch, hdfs-3672-5.patch,
> hdfs-3672-6.patch, hdfs-3672-7.patch, hdfs-3672-8.patch, hdfs-3672-9.patch
>
>
> Currently, HDFS exposes on which datanodes a block resides, which allows
> clients to make scheduling decisions for locality and load balancing.
> Extending this to also expose on which disk on a datanode a block resides
> would enable even better scheduling, on a per-disk rather than coarse
> per-datanode basis.
> This API would likely look similar to Filesystem#getFileBlockLocations, but
> also involve a series of RPCs to the responsible datanodes to determine disk
> ids.
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