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https://issues.apache.org/jira/browse/CASSANDRA-11550?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=15579164#comment-15579164
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Dikang Gu commented on CASSANDRA-11550:
---------------------------------------

I test this in one of our cluster, in default fanout_size=10 case, the sstables 
look like this: [1, 11/10, 135/100, 98, 0, 0, 0, 0, 0], in fanout_size=6 case, 
the sstables look like this:  [1, 7/6, 38/36, 142, 0, 0, 0, 0, 0]. So in this 
case, after the change, the highest level for sstables is still level 3, and we 
can see improvements (reduce) in space usage, write amplification, and 
compaction cpu usage. I can see ~20% improvements on those areas.

Some graphs are attached.


> Make the fanout size for LeveledCompactionStrategy to be configurable
> ---------------------------------------------------------------------
>
>                 Key: CASSANDRA-11550
>                 URL: https://issues.apache.org/jira/browse/CASSANDRA-11550
>             Project: Cassandra
>          Issue Type: New Feature
>          Components: Compaction
>            Reporter: Dikang Gu
>            Assignee: Dikang Gu
>              Labels: lcs
>             Fix For: 3.x
>
>         Attachments: bytes_compacted.png, cpu_nice.png, 
> write_amplification.png
>
>
> Currently, the fanout size for LeveledCompactionStrategy is hard coded in the 
> system (10). It would be useful to make the fanout size to be tunable, so 
> that we can change it according to different use cases.
> Further more, we can change the size dynamically.



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