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Natale Galioto edited comment on CASSANDRA-12907 at 11/29/16 10:52 PM: ----------------------------------------------------------------------- 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 than me of the whole system. Indeed, I don't know what really happens with snapshots, backup, and many other things I cannot think about. I apologize if I got something really wrong. Thanks. was (Author: xmas79): 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. -- This message was sent by Atlassian JIRA (v6.3.4#6332)