load spikes

Does anyone happen to recognize the periodic spikes seen on friday and saturday here:

http://server1.liquenox.net/mrtg/load.html

It's not a cronjob. There were a couple of bursts of the same sort of thing on wednesday and thursday too (where the spikes were higher).

When I look at the 'top' processes, I'm seeing 4-8 httpd apache processes, a lot of which are running for up to a minute. I don't know if that's common or not.

Just wondered if someone might recognize the pattern?

Rowan.

Doesn't ring a bell. They don't appear to have a pattern either (different days/times)
Could be anything really. Do you have Automatic updates for some programs? (i.e. DirectAdmin etc.) that don't use cronjobs to initiate the process?

If you were able to pinpoint logs for the duration of those spikes, they might give you a better idea of who or what is causing it.

Actually, I wasn't talking about those HUGE spikes. They're caused by some sort of mysql problem (suddenly we'll start getting a flood of mysql processes until they're all used up and the server basically grinds to a halt -- restart of mysql a few times usually fixes it).

I'm referring to the regularly spaced peaks seen in the "daily" graph at the top. They seem to be very clearly running at regular intervals but they're not coming from cron. And there's no obvious cause showing in the process list. Very odd.

Row.