I'm running a pretty standard LAMP stack on Fedora 15, mostly in support of some Drupal sites. Things generally seem to be running fine, but occasionally the disk on the machine will start to work noticeably harder than it usually does. My limited system debugging skills have found this:
'top' reports that httpd and mysqld are indeed active, taking up maybe 3-4% of what is otherwise a mostly idle machine.
There are no changes in the httpd log files, and nothing out of the ordinary is showing up on other system logs. So the obvious answer of "somebody's hitting your websites, dummy" doesn't seem to be the case.
resetting httpd with "apachectl graceful" has no effect. However, "apachectl stop" followed by "apachectl start" generally calms the machine down -- the disk churning stops.
I believe the machine is secure; I have no reason to believe that there's any hackery going on. (Of course, I suppose that's usually the case...)
I'd be surprised (but happy!) if that was enough for somebody to tell me what's going on, but is there any advice out there on how I might dig into the machine a bit more and figure out what's going on? Thanks!