MySQL Performance Woody Vs Sarge

[Simon <dev@networker.co.nz>]

Hi There, I have a strange issue with mysql performance... We are 
running sarge on our production web server and woody on our dev 
server... MySQL is the only issue we have:

Both servers are running MySQL 4.0.24, one Debian_4 (woody) and one 
Debian_5 (sarge)... Both my.cnf files are pretty much the same, both 
servers are 1.5Mhz single processor AMD with 512MB RAM, both running 
software RAID 1 (2 disks) where the mysql data is stored....

We have a database with about 900,000 records in it... serial numbers 
for products... Looking up the woody box:

select * from serial_numbers where serial_number is 'XXXXXXXXXXXXXX';

works (pretty much) instantly, where as the sarge box takes about 3 seconds.

How do i start figuing out this issue?

The only difference i can find is that an htparm on the RAID drive:

woody:

Timing buffer-cache reads:   128 MB in  0.46 seconds =278.26 MB/sec
Timing buffered disk reads:  64 MB in  1.33 seconds = 48.12 MB/sec

sarge:

Timing cached reads:   196 MB in  3.38 seconds =  57.98 MB/sec
Timing buffered disk reads:  130 MB in  3.01 seconds =  43.22 MB/sec

Seems to directly relate to the issue? I dont know.

Thanks,

Simon