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https://issues.apache.org/jira/browse/CASSANDRA-12907?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=15706809#comment-15706809
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Natale Galioto commented on CASSANDRA-12907:
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I got some basic stuff work, and I was able to map all non "-Data.db" files to
another location. The code can be checked on my fork on github at:
https://github.com/xmas79/cassandra/tree/CASSANDRA-12907
This is the commit:
https://github.com/xmas79/cassandra/commit/c72d0ea284bd54877ac1f808e7333e6fbbba4c93
This currently works for one "ssd" directory, and one "data" directory only.
The code changes the constructor of
"src/java/org/apache/cassandra/io/sstable/Descriptor.java", the descriptor of
the sstable, and mangles the "baseFilename" function based on the requested
"Component".
It really requires a deep review by people that have much more understanding of
the whole system.
Thanks.
> Different data directories for SSDs and HDDs at configuration level
> -------------------------------------------------------------------
>
> Key: CASSANDRA-12907
> URL: https://issues.apache.org/jira/browse/CASSANDRA-12907
> Project: Cassandra
> Issue Type: Improvement
> Reporter: Natale Galioto
> Labels: performance
>
> Currently, users can speed up some CFs by symlinking its data directory to
> fast media such as SSDs. In my opinion, instead, configuration file should
> allow two different sets of directory: one dedicated to spindles, one
> dedicated to SSDs.
> This would allow a "once and for all mixed SSD & HDD configuration", instead
> of continuously symlinking the "right" directory each time a CF is created
> (due to the name mangling of the CF directories).
> And this in turn would allow a priori knowledge on disk structures, and would
> allow to place indexes of all sort (lookup, partition, etc... everything that
> is needed to "just" locate data) on fast SSDs, speeding up ALL the CFs
> instead of only one, while the HDDs could be used just for data retrieval and
> sequential reads.
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