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https://issues.apache.org/jira/browse/CASSANDRA-8460?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=14589084#comment-14589084
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Jeff Jirsa commented on CASSANDRA-8460:
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Pushed a version, which I believe works as described. Would appreciate some
feedback, and then if it looks promising, I'll finish it up with adding unit
tests.
https://github.com/jeffjirsa/cassandra/commit/079b22136d178937b28b82326f132e33e96f6cad
A few explicit questions for [~krummas] and [~Bj0rn] :
1) If compaction strategy calls for archive, but no archive disk is available
(not defined or otherwise full), I'm falling back to standard disk. Agree?
https://github.com/jeffjirsa/cassandra/commit/079b22136d178937b28b82326f132e33e96f6cad#diff-2c2b50ecd5e8515531c5d041117c9b4fR371
2) I originally planned to explicitly prohibit compaction of N files in
archival disk, but I couldn't convince myself if that made sense. Instead, I'm
allowing it if sstable_max_age_days allows it (if you set archive lower than
max age, you could conceivably compact on archival disk tier). Agree?
3) In the case where archived sstables can still be compacted, it's possible in
some windows to have them compacted with sstables on the faster standard disk.
In those cases, I'm making a judgement call that if any of the source sstables
were archived, the resulting sstable will also be archived. Agree?
https://github.com/jeffjirsa/cassandra/commit/079b22136d178937b28b82326f132e33e96f6cad#diff-7a9ada329d886c1871344b1d6fceec5cR56
4) Finally, I was trying to determine the right way to tell if an sstable was
already archived. The logic I eventually used was simply parsing the path of
the sstable and seeing if it was in the array of archive directories (
https://github.com/jeffjirsa/cassandra/commit/079b22136d178937b28b82326f132e33e96f6cad#diff-894e091348f28001de5b7fe88e65733fR1665
) . I'm not convinced this is best, but I didn't know if it was appropriate to
extend sstablemetadata or similar to avoid this. Thoughts?
> Make it possible to move non-compacting sstables to slow/big storage in DTCS
> ----------------------------------------------------------------------------
>
> Key: CASSANDRA-8460
> URL: https://issues.apache.org/jira/browse/CASSANDRA-8460
> Project: Cassandra
> Issue Type: Improvement
> Reporter: Marcus Eriksson
> Assignee: Jeff Jirsa
> Labels: dtcs
>
> It would be nice if we could configure DTCS to have a set of extra data
> directories where we move the sstables once they are older than
> max_sstable_age_days.
> This would enable users to have a quick, small SSD for hot, new data, and big
> spinning disks for data that is rarely read and never compacted.
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