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From:Harald Fuchs Date:August 29 2002 11:22am
Subject:Re: MySQL/InnoDB-4.0.3 is released
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In article <20020828151013.GA12910@stripped>,
Dan Nelson <dnelson@stripped> writes:

> On a similar topic, many OSes support "Direct I/O" on files, which
> causes reads and writes to bypass the system's buffer cache.  It's
> usually enabled by adding the O_DIRECT (or O_DIRECTIO) flag to your
> open() call.  From a quick Google search, FreeBSD and IRIX use
> O_DIRECT, Tru64 uses O_DIRECTIO, and Solaris has you call a directio()
> function on the file descriptor after you open the file.

> Adding this should really help performance on large InnoDB tablespaces,
> and keeps you from having to fall back to raw partitions for unbuffered
> IO, which are a pain to manage.

Why?
* raw /dev/raw/rawN /dev/whatever
* chown mysql.daemon /dev/raw/rawN /dev/whatever               (not sure which)
* innodb_data_file_path = /dev/raw/rawN:xxxMnewraw
* innodb_data_file_path = /dev/raw/rawN:xxxMraw
and you're done.

It's hard to change/extend such a setup, but unbuffered raw devices
have the advantage that they bypass not only the buffer cache, but
also the filesystem.

[ Filter fodder: SQL query ]
Thread
MySQL/InnoDB-4.0.3 is releasedHeikki Tuuri28 Aug
  • Re: MySQL/InnoDB-4.0.3 is releasedHarald Fuchs28 Aug
    • Re: MySQL/InnoDB-4.0.3 is releasedDan Nelson28 Aug
  • Re: MySQL/InnoDB-4.0.3 is releasedHeikki Tuuri28 Aug
  • Re: MySQL/InnoDB-4.0.3 is releasedHarald Fuchs29 Aug
Re: MySQL/InnoDB-4.0.3 is releasedHeikki Tuuri28 Aug
  • Re: MySQL/InnoDB-4.0.3 is releasedHarald Fuchs29 Aug