On Tue, 2004-08-10 at 10:18 -0700, Josh Berkus wrote:
> Guys, just so you know:
>
> OSDL did some testing and found Ext3 to be perhaps the worst FS for PostgreSQL
> -- although this testing was with the default options. Ext3 involved an
> almost 40% write performance penalty compared with Ext2, whereas the penalty
> for ReiserFS and JFS was less than 10%.
>
> This concurs with my personal experience.
>
Yes, I have been wondering about the relative trade offs between
underlying file systems and pgsql.
For metadata journalled filesystems, wouldn't fdatasync be a better
option, since the fs is journalling the metadata anyway?
With its default settings (data=ordered), ext3 is making a guaranty that
after a crash, the filesystem will not only be in a consistent state,
but the files (including the WAL) will not contain garbage, though their
contents may not be the latest. With reiserfs and JFS, files can
contain garbage. (I'm not sure what the implications of all this for
pgsql are.)
And wouldn't the following comparisons with ext3 be more interesting:
ext3,data=writeback,fdatasync vs Other_Journalled_FS,fdatasync
or
ext3,data=journal,open_sync vs Other_Journalled_FS,fdatasync
Just wondering.
-Steve