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From "Benedict (JIRA)" <j...@apache.org>
Subject [jira] [Commented] (CASSANDRA-6993) Windows: remove mmap'ed I/O for index files and force standard file access
Date Tue, 09 Dec 2014 11:40:12 GMT

    [ https://issues.apache.org/jira/browse/CASSANDRA-6993?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=14239307#comment-14239307
] 

Benedict commented on CASSANDRA-6993:
-------------------------------------

Replacing isUnix() with !isWindows() is not functionally equivalent; this will capture Mac,
Solaris, OpenBSD, FreeBSD and others as well, although in many situations this actually adequately
captures what we want (such as for your specific change) it likely won't in all cases. 

As with CASSANRA-8038 this would benefit from sanitising our OS detection. Perhaps we could
split this out into a minor ticket these both depend upon, as we have a bit of a mess right
now that permits these sorts of logical mismatches to crop up. We should probably group POSIX
compliant OSes together, and POSIX compliant file systems together, one of which is probably
what we generally mean when we say isUnix().


> Windows: remove mmap'ed I/O for index files and force standard file access
> --------------------------------------------------------------------------
>
>                 Key: CASSANDRA-6993
>                 URL: https://issues.apache.org/jira/browse/CASSANDRA-6993
>             Project: Cassandra
>          Issue Type: Improvement
>            Reporter: Joshua McKenzie
>            Assignee: Joshua McKenzie
>            Priority: Minor
>              Labels: Windows
>             Fix For: 3.0, 2.1.3
>
>         Attachments: 6993_2.1_v1.txt, 6993_v1.txt, 6993_v2.txt
>
>
> Memory-mapped I/O on Windows causes issues with hard-links; we're unable to delete hard-links
to open files with memory-mapped segments even using nio.  We'll need to push for close to
performance parity between mmap'ed I/O and buffered going forward as the buffered / compressed
path offers other benefits.



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