There are some very useful linux commands / utilities, which can be used to monitor the system performance at any time. Some of them, which I recommend for any sysadmin are summarized below:
- vmstat
Reports virtual memory statistics, for example:
$ vmstat procs -----------memory---------- ---swap-- -----io---- --system-- -----cpu------ r b swpd free buff cache si so bi bo in cs us sy id wa st 0 0 4 1325196 151544 299408 0 0 2 54 0 0 2 1 97 0 0