Regular high load peaks on servers

[Julien <julien@no-log.org>]

Hi,

Since quite a long time now, we observe the same phenomenon on three
web servers we have on two different places. They regularly have 
high load peaks, until 20 to 50. These peaks append very regularly
(from once a day to several an hour), and we can't explain why. It
doesn't seem to be linked to a special increase in traffic or web
requests.

Two of the three servers are load-balanced web frontends running
apache with nfs mounts. The third is an autonomous server with web,
mail, mysql… services, without nfs. The three run under Debian Lenny.

I know nobody could really solve this problem without access to the
machines and logs, but I wonder if someone already experienced this
sort of regular load peaks.

Thanks in advance for any help,

-- 
Julien