[CentOS] ext4 in CentOS 5.6?

Tue Jul 5 14:10:50 UTC 2011
Charles Polisher <cpolish at surewest.net>

Christopher Chan wrote:
> James Hogarth wrote:
> >>>
> >>> If you're running a database on it, you might re-think using a
> >>> journaled filesystem. For that, ext2 will be faster and much
> >>> less prone to unrecoverable data loss.
> >>
> >> Did you mean EXT4, or in actual fact EXT2? I thought EXT4 was faster than
> >> EXT2?

In general and with some simplifiying assumptions, a database
consists of statically pre-allocated files. The process of extending
the files happens at birth. The relative speed over the lifetime
of the database is dominated by raw I/O, not by extending the files.

> >
> > The optimum on an EXT basis for a filesystem that does not require
> > journaling going forwards would be EXT4 with no journal... that way
> > you get the benefit of extents etc without a journal slowing you
> > down.... A better option than EXT2 ;)
> 
> 
> Test, test, and test again for your own particular case.

Couldn't agree more! 

A reminder that blind trust in filesystems is not always well placed:
http://thread.gmane.org/gmane.comp.file-systems.ext4/6702

Everyone uses foo, therefore foo is what you should use:
http://www.nizkor.org/features/fallacies/appeal-to-popularity.html

Important Person uses foo, therefore foo is what you should use:
http://www.nizkor.org/features/fallacies/appeal-to-authority.html

I've been using foo for years in production with no problems:
maybe http://www.nizkor.org/features/fallacies/composition.html 

(I'm sharpening my axe for the "Use ZFS, it's bulletproof" discussion.)

-- 
Charles Polisher