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https://issues.apache.org/jira/browse/HBASE-57?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=12693621#action_12693621
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stack commented on HBASE-57:
----------------------------
The going direct to local blocks reading is HADOOP-4801. In summary, the
payoff short-circuiting the datanode is small, and yet to be seen -- at least
to date -- and it seems doubtful that a second route to the data will be opened
because of security concerns, etc. Thats my take on the issue (It could change
of course).
I think that if we only made savings in network traffic, that'd be reason
enough to implement locality algorithms. JK makes an interesting point above
that we could manufacture hot datanodes if we blindly serve regions from a
datanode that hosts all the data but this can happen now since we operate
blindly and its only smart use of the locality info that will help damp hot
spots.
Samuel, if still interested, have you made petition to become a GSOC student
using this issue as your project? (Add in some of JKs notes on need to
research what happens in a running cluster so know best what to implement).
> [hbase] Master should allocate regions to regionservers based upon data
> locality and rack awareness
> ---------------------------------------------------------------------------------------------------
>
> Key: HBASE-57
> URL: https://issues.apache.org/jira/browse/HBASE-57
> Project: Hadoop HBase
> Issue Type: Improvement
> Components: master
> Affects Versions: 0.2.0
> Reporter: stack
> Fix For: 0.20.0
>
>
> Currently, regions are assigned regionservers based off a basic loading
> attribute. A factor to include in the assignment calcuation is the location
> of the region in hdfs; i.e. servers hosting region replicas. If the cluster
> is such that regionservers are being run on the same nodes as those running
> hdfs, then ideally the regionserver for a particular region should be running
> on the same server as hosts a region replica.
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