David Lang wrote:
On Tue, 14 Mar 2006, Chris wrote:
The only other thing I can see is the old server is ext2:
/dev/hda4 on / type ext2 (rw,errors=remount-ro)
the new one is ext3:
/dev/hda2 on / type ext3 (rw)
this is actually a fairly significant difference.
with ext3 most of your data actually gets written twice, once to the
journal and a second time to the spot on the disk it's actually going to
live.
in addition there are significant differences in how things are arranged
on disk between the two filesystems, (overridable at mount, but only
changes future new files). the ext3 layout is supposed to be better for
a general purpose filesystem, but I've found common cases (lots of files
and directories) where it's significantly slower, and I think postgres
will fall into those layouts.
try makeing a xfs filesystem for your postgres data and see what sort of
performance you get on it.
Interesting.
To be honest I think I'm just lucky with my really old server. I can't
see any particular tweaks in regards to drives or anything else. I have
another server running postgres 7.4.something and it's as slow as the
8.1 system.
#1 is running 2.4.x kernel - pg 7.4 (debian package) - good performance.
ext2.
#2 is running 2.2.x kernel (I know I know).. - pg 7.4 (debian package)
- reasonable performance. ext2.
#3 is running 2.6.x kernel - pg 8.1 (fedora package) - reasonable
performance. ext3.
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