top. View overall system performance. This tool displays CPU usage, memory usage, and swap usage for the system and for individual processes running on the system.

iostat. Monitor the loading operation for every disk attached to the database server. Iostat displays the percentage of time that the disk is physically active. If you use disk arrays, use utilities provided with the disk arrays instead of iostat.

vmstat. Monitor disk swapping actions.

sar. View detailed system activity reports of CPU, memory, and disk usage. You can use this tool to monitor CPU loading. It provides percent usage on user, system, idle time, and waiting time. You can also use this tool to monitor disk swapping actions.