Dan, ----- Original Message ----- From: "Dan Nelson" <[EMAIL PROTECTED]> To: "Harald Fuchs" <[EMAIL PROTECTED]> Cc: <[EMAIL PROTECTED]>; <[EMAIL PROTECTED]> Sent: Wednesday, August 28, 2002 6:10 PM Subject: Re: MySQL/InnoDB-4.0.3 is released
> In the last episode (Aug 28), Harald Fuchs said: > > I think there's something missing in the changelog. About a month > > ago, someone named Christian Jaeger from ETH Zurich asked about > > unbuffered raw device support for Linux. You replied immediately > > with two sets of patches for 3.23.x (regaring unaligned access) which > > apparently fixed the problems, for Mr. Jaeger at least. When I tried > > to apply those patches to 4.0.2, I still got operating system error > > #22. Thus I decided to wait for 4.0.3. > > 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. this may come some time in future. It is just a small change to innodb_flush_method in my.cnf. I am cautious to use O_DIRECT on Unixes. There is evidence that fdatasync() corrupted files both in Linux and Solaris. That is why also the InnoDB flush method O_DSYNC is currently internally mapped to normal O_SYNC. Thus the problem in these nonstandard file i/o methods is that they often seem to be buggy. But giving users the option to test these would be good. > 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. > > -- > Dan Sql Query Nelson > [EMAIL PROTECTED] Best regards, Heikki --------------------------------------------------------------------- Before posting, please check: http://www.mysql.com/manual.php (the manual) http://lists.mysql.com/ (the list archive) To request this thread, e-mail <[EMAIL PROTECTED]> To unsubscribe, e-mail <[EMAIL PROTECTED]> Trouble unsubscribing? Try: http://lists.mysql.com/php/unsubscribe.php
