linux redhat 5.4 - swap while memory is still available

I have a Sybase server with CentOS 5 which causes no swap. The trick is to set swappiness to 0 and to left enough memory for OS. The server has 16GB (10GB for Sybase and 6GB for OS and other services). Start with a smaller Sybase cache and increase it progressively.

[root@db2 ~]# tail -2 /etc/sysctl.conf 
# Set Swappiness
vm.swappiness = 0