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Mouhamadou Diaw

Monitoring Linux With Nmon

I was looking for tools to monitor linux servers and I found an interesting one nmon ( short for Nigel’s Monitor). I did some tests. In this blog I am describing how to install nmon and how we can use it
I am using a Oracle Enterprise Linux System.

[root@condrong nmon]# cat /etc/issue
Oracle Linux Server release 6.8
Kernel \r on an \m

[root@condrong nmon]#

For the installation I used the repository epel

wget http://dl.fedoraproject.org/pub/epel/6/x86_64/epel-release-6-8.noarch.rpm
rpm -ivh epel-release-6-8.noarch.rpm 
yum search nmon
yum install nmon.x86_64

Once installed, the tool is launched by just running the nmon command

[root@condrong nmon]# nmon

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If we type c we have CPU statistics
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If we type m we have memory statistics
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If we type t we can see Top Processes and so on
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nmon can be also scheduled. The data are collected in a file and this file can be analyzed later. For this we can use following options

OPTIONS
       nmon follow the usual GNU command line syntax, with long options starting
       with  two  dashes  (‘-’).   nmon  [-h] [-s ] [-c ] [-f -d
        -t -r ] [-x] A summary of options is included below.

       -h     FULL help information

              Interactive-Mode: read startup banner and type:  "h"  once  it  is
              running For Data-Collect-Mode (-f)

       -f            spreadsheet output format [note: default -s300 -c288]
              optional

       -s   between refreshing the screen [default 2]

       -c    of refreshes [default millions]

       -d     to increase the number of disks [default 256]

       -t            spreadsheet includes top processes

       -x            capacity planning (15 min for 1 day = -fdt -s 900 -c 96)

In my example I just create a file my_nmon.sh and execute the script

[root@condrong nmon]# cat my_nmon.sh 
#! /bin/bash
nmon -f -s 60 -c 30

[root@condrong nmon]# chmod +x my_nmon.sh 
[root@condrong nmon]# ./my_nmon.sh

Once executed, the script will create a file in the current directory with an extension .nmon

[root@condrong nmon]# ls -l *.nmon
-rw-r--r--. 1 root root 55444 Oct 18 09:51 condrong_181018_0926.nmon
[root@condrong nmon]#

To analyze this file, we have many options. For me I downloaded the nmon_analyzer
This tool works with Excel 2003 on wards and supports 32-bit and 64-bit Windows.
After copying my nmon output file in my windows station, I just have to launch the excel file and then use the button Analyze nmon data
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And below I show some graphs made by the nmon_analyzer
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Conclusion
As we can see nmon is a very useful tool which can help monitoring our servers. It works also for Aix systems.

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Mouhamadou Diaw
Mouhamadou Diaw

Consultant