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https://issues.apache.org/jira/browse/CASSANDRA-3948?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=13214616#comment-13214616
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Pavel Yaskevich commented on CASSANDRA-3948:
--------------------------------------------
We algorithm behind it - we do fadvice(fd, <start_position>, 0) after each
128MB of data written, flush is done in the process of each re-buffer (which is
each 64KB by default) so we can skip doing sync when we do fadvice() and just
use 0 which would hint kernel so skip everything starting from
<start_position>.
> SequentialWriter doesn't fsync() before posix_fadvise()
> -------------------------------------------------------
>
> Key: CASSANDRA-3948
> URL: https://issues.apache.org/jira/browse/CASSANDRA-3948
> Project: Cassandra
> Issue Type: Bug
> Components: Core
> Reporter: Peter Schuller
> Assignee: Pavel Yaskevich
> Fix For: 1.1.0
>
>
> This should make the fadvising useless (mostly). See CASSANDRA-1470 for why,
> including links to kernel source. I have not investigated the history of when
> this broke or whether it was like from the beginning.
> For the record I have not confirmed this by testing, only by code inspection.
> I happened to notice it working on other things, so there is some chance that
> I'm just mis-reading the code.
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