nmon is a popular system monitor

System monitor

A system monitor is a hardware- or software- based system used to monitor resources and performance in a computer system.Software monitors occur more commonly, sometimes as a part of a widget engine. These monitoring systems are often used to keep track of system resources, such as CPU usage and...

 tool for the AIX and Linux

Linux

Linux is a Unix-like computer operating system assembled under the model of free and open source software development and distribution. The defining component of any Linux system is the Linux kernel, an operating system kernel first released October 5, 1991 by Linus Torvalds...

 operating systems.

Description

The original nmon was a freely downloadable tool for AIX 4.3 from the AIX wiki. It was also rewritten for the Linux operating system running on IA-32, x86-64, RS/6000 and Power processor and Mainframe and released by IBM to open source

Open source

The term open source describes practices in production and development that promote access to the end product's source materials. Some consider open source a philosophy, others consider it a pragmatic methodology...

 in July 2009. Its features were then bundled as part of the AIX operating systems from AIX 5.3 TL09 and AIX 6.1 TL02 within the topas command. It is used by AIX and Linux Systems Administrators and performance tuning specialists around the world.

Features

The features that make nmon unique are:

• It is free and available for download from the IBM AIX Wiki website.
• It is a single binary (one for each OS release), so installation is very simple.
• There are two modes available:

1. In Online Mode it uses curses
   Curses (programming library)
   curses is a terminal control library for Unix-like systems, enabling the construction of text user interface applications.The name is a pun on the term “cursor optimization”. It is a library of functions that manage an application's display on character-cell terminals .- Overview :The curses API...
   
    for efficient screen handling, which updates the terminal frequently for real-time monitoring.
2. In Capture Mode, the data is saved to a file in CSV
   Comma-separated values
   A comma-separated values file stores tabular data in plain-text form. As a result, such a file is easily human-readable ....
   
    format for later processing and graphing. The file also includes important configuration details that are useful for recommending tuning.
   • nmon takes very little CPU time to run but captures the key performance numbers.
   • Has been in development for 10 years and includes many features requested by performance monitoring and systems administrator users.
   • nmon concentrates on useful performance information for the performance tuner and in a concise layout to aim understanding. This includes: CPU, memory, disks, adapters, networks, NFS, Kernel statistics, File-systems, Workload Manger (AIX), Workload Partitions (AIX) and Top Processes.
   • There are three main post processing tools, which are all available for free:
3. nmon Analyser is an Excel spreadsheet for graphing the collected data.
4. nmon2rrd creates Round-Robin Database (RRD) files via the Open Source RRDtool
   RRDtool
   RRDtool aims to handle time-series data like network bandwidth, temperatures, CPU load, etc...
   
    and then generates graphs and html files to display the data and graphs on a website.
5. nmon2web is similar to nmon2rrd but based on Perl.
   • These tools make it simple to produce reports with the key performance graphs or to automate the collection of performance data and create a website to aid tuning.
   • Because nmon includes support for older AIX releases, Linux running on x86, POWER and Mainframe platforms nmon is a tool that can be used to monitor them all.
   • Discussion, hints and tips are hosted on the IBM Performance tools Forum
   • nmon has been presented at many IT conferences including the UK UNIX User Group 2006 and IBM Power Systems Technical Universities held in the USA, European and Asia.

Alternatives

On AIX there is the topas command that can output reports to a file but this is not in a format that can be used easily as a source for a spread sheet or web tools like rrdtool.

On Linux there is the top command

Top (Unix)

top is a program found in many Unix-like operating systems. It produces an ordered list of running processes selected by user-specified criteria, and updates it periodically. Default ordering by CPU usage, and only the top CPU consumers shown top shows how much processing power and memory are...

 which is good for CPU and processes but does not cover disks and networks. For disk I/O, the iostat

Iostat

iostat is a computer system monitor tool used to collect and show operating system storage input and output statistics.It is often used to identify performance issues with local disks or networked file systems such as NFS....

 command can give you the details. But neither of these commands allow saving data in a format suitable for a spreadsheet or simple further processing.

For monitoring many systems at a higher level the Ganglia

Ganglia (software)

Ganglia is a scalable distributed system monitor tool for high-performance computing systems such as clusters and grids. It allows the user to remotely view live or historical statistics for all machines that are being monitored.-Ganglia:It is based on a hierarchical design targeted at...

open source tool is a good addition to lower detailed level. nmon and Ganglia both support UNIX (including AIX) and Linux systems.

External links

• Updated Link to Wiki and Download Web page
• nmon (Performance Tools) Forum
• nmon Analyser Webpage
• Other similar free Performance tools for AIX
• Older but useful nmon Article
• Ganglia open source project home website
• nmon for Linux website - for the source code and Linux binaries for Intel, AMD, Power and Mainframe.
• nmon manual page in the AIX Operating System
• IBM Systems magazine article including nmon