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https://issues.apache.org/jira/browse/HBASE-55?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=12568412#action_12568412
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Jim Kellerman commented on HBASE-55:
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+1 on defining what is server load.
When we first defined it it was very simplistic and about the best we could do
at the time.
Now we have multiple factors:
- update rate
- read rate
- memory pressure on region server
part of this will come from HBASE-70, but it is a more subtle problem, because
you have to take into
account hot spots (lots of updates), cold spots (almost no updates), memory
consumption on the
region server, etc.
Aside from #regions being served by a region server and the number of requests
it had served
since last heartbeat, none of these other considerations were in play.
What we need to do wrt region servers is come up with a metric that represents
'load factor'
If people have ideas on what that computation should be we'd be greatly
interested in
hearing them.
Most of our test cases are pretty artificial, and do not represent a real world
load, so trying to come
up with a computation that tells us that a region server is too busy to accept
more load is difficult.
> [hbase] Improve Master region assignment function
> -------------------------------------------------
>
> Key: HBASE-55
> URL: https://issues.apache.org/jira/browse/HBASE-55
> Project: Hadoop HBase
> Issue Type: Improvement
> Components: regionserver
> Reporter: Bryan Duxbury
> Fix For: 0.2.0
>
>
> We would like the master's region assignment function to take into account
> more factors when choosing where to assign regions.
>
> - More advanced accounting of load on regionserver - memory, # requests, etc
> - Don't deploy both daughter regions to the same regionserver
> - Assign regions where the underlying DFS blocks are hosted if possible
> Please add additional ideas in comments as they come up.
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