Very high load spikes

["Mimmus" <dviggiani tiscali it>]

Hi,
I'm experiencing very high (even 40-50!) load peaks, during only a few of 
seconds.
During these peaks, user cpu is usually low but system cpu is ~80-99%.
System is a DL740 with 8 CPUs and 32 GB of RAM with Linux Red Hat Advanced 
Server 3.0 (kernel 2.4.21-9.0.3.ELhugemem), connected by a 2GBps SAN to an 
EVA3000 disk-array.
It is an Oracle-only machine (but 9 istances are active), no other 
significative processes are running.
I tuned it using usual parameters from Oracle (eventually I can attach a 
kernel parameters list).
It seems that there is no exceptional I/O or paging/swap activity during 
peaks but I'm not sure (I'm using dstat - 
http://dag.wieers.com/home-made/dstat/ - to monitor several metrics at same 
time).

How can I identify what system does when load is high?

Any help will be appreciated.
Domenico Viggiani