I noticed after boot up, if i don't log in after a while, there's a flurry of disk activity going
on .. i also get mail as root about some cron job.. sorry, i forget exactly what (don't
have machine here now) but it was dealing with some maintenance thing ..

in addition, after logging in, i notice regular short spurts of disk i/o no matter what i'm
doing.. even purely idle .. it's very regular like precisely every min? or maybe 30-40
secs? i notice it because the scsi drive i use is very loud with each head movement
making a CLAK!

so i just want to know what's going on ..
this is a RH9 install with all packages and default security settings, software raid, and
no network

thanks

As far as I've been informed Linux does not instantly write info to the partions so this could simply be your system performing routing maintenance such as saving, defragging etc.... You can force things to be written, however the clockwork cycle and the cron job you're describing makes it sound legit - Just my 2 bits however I could be wrong - If you are worried about security and would like to harden your box I'd recommend looking at the following site:

http://www.linuxexposed.com/modules....&mode=&order=0

Take care!