Thks Darshan, sorry for late answer
We have dedicated cache for syslogs and , for disks , as numerous sites we use EMC sans. Nowadays, I cannot really choose where to install files for segments , and we don't use segments at all then .
I plan to put RDDB option for temporary databases for decreasing log writes, and I have also to increase user log cache and session tempdb log too , although already both are 128K sized .
reagrds
Marc