The system administrator should monitor system performance to see if any bottlenecks or other system problems are developing. Several system utilities are useful in this regard.
The sar command is a very powerful way to look at various aspects of system performance. Run this from the root account. The following is the general syntax of sar:
sar -REPORT LEN CNT
The following are your available options:
REPORT is a single-letter option to tell what report to run. Here are three of the most useful reports:
-u reports CPU usage.
-b reports disk buffer and cache access.
-d reports disk drive usage.
There are many more reports as well. Check the man page on sar.
LEN tells how long to monitor the system ...