The nmon (Nigel’s Monitor) tool was written initially for AIX to monitor system performance, but there are plenty of distributions available now so people can use it on a variety of operating systems these days, including flavours of Linux and even the recent Raspberry Pi (mini ARM based computer).
It’s one of my favourite performance monitoring tools out there, and can be used to obtain information on CPU, memory, network, disk I/O, top processes etc. As well as running nmon interactively, you can also run it in recording mode to build up historical statistics for your server(s).
To install nmon on Linux, it’s as straight forward as this:
cd /usr/bin wget http://sourceforge.net/projects/nmon/files/nmon_x86_64_rhel6 chmod +x nmon_x86_64_rhel6 ln -s nmon_x86_64_rhel6 nmon export NMON=cmt nmon
NOTE: If your PuTTY session starts rendering lines as “qqqqqqqqq” try changing the following setting in your PuTTY session and reconnect:
Connection > Data > Terminal-type string > change from “xterm” to “linux”
If you want to install nmon on a different OS, just browse the following URL and fetch the appropriate release: http://sourceforge.net/projects/nmon/files
The following keyboard shortcuts can be used turn on (and off) statistics about various components:
t Top processes
V Virtual memory
n Network adapters
h Help screens
v Verbose mode
q Exit nmon
If you prefer, rather than running nmon and then hitting c, m, and t each time to view CPU, memory, and top processes information (in that order) for example, you can simply export the settings before hand (or add them to your profile) as I did above, like so:
There is a good article on the IBM developerWorks site here (focusing on the AIX versions) which also explains how to run nmon in recording mode and gather historical snapshots.