How to Setup nmon – Monitor Linux Performance

Nmon (Nigel’s Monitor) is a great performance monitoring tool for Linux operating system.

It was written initially for AIX to monitor system performance. nmon for Linux can be used to collect informations on CPU, memory, network, disk I/O, top processes etc.

System administrator can use nmon as a tuner or benchmark tool that will provide performance information in one go.

It can output the data on the screen or can be save the data into a comma separated file for analysis and longer term data capture.

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Steps to setup nmon on linux operating system.

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2. Rum yum command to install nmon :

# yum install nmon -y

3. Example of nmon command usage :

Type command :

# nmon

Sample output :
setup nmon

nmon keyboard shortcuts

q – To stop and exit nmon.
h – To see quick help (hint) screen and press h again to remove the hints.
Use the following command to turn on or off stats:
c – See cpu stats.
m – See memory stats.
d – See disk stats.
k – See kernel stats.
n – See network stats.
N – See NFS stats.
j – See file system stats.
t – See top process.
V – See virtual memory stats.
. – See only busy disks/procs.
v – Verbose mode (display as Ok/warning/danger on screen).

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Sample outputs :
setup nmon

4. If you prefer to run nmon as a daemon in the background, run the below command, nmon will complete the data file collection and it will save in a file *.nmon file such as oss_140817_2359.nmon with the details of the command as below :

# nmon -f -s2 -c 30
-f : Start data collect mode and output in spreadsheet format.
-s 2 : Wait between 2 seconds or capture data every 2 seconds.
-c30 : Total number of refreshes (30).


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