Usage notes: This
nmon tool is NOT OFFICIALLY SUPPORTED. No warrantee is given or implied, and you cannot obtain help with it from IBM. If you have a question on
nmon, please go on the Performance Tools Forum site (see Resources) so that others can find and benefit from the answers. To protect your email address from junk mail, you need to create a USER ID first (takes 20 seconds at most).
nmon tool runs on:
- AIX® 4.1.5, 4.2.0 , 4.3.2, and 4.3.3 (
nmonVersion 9a: This version is functionally established and will not be developed further.)
- AIX 5.1, 5.2, and 5.3 (
nmonVersion 10: This version now supports AIX 5.3 and POWER5™ processor-based machines, with SMT and shared CPU micro-partitions.)
- Linux® SUSE SLES 9, Red Hat EL 3 and 4, Debian on pSeries® p5, and OpenPower™
- Linux SUSE, Red Hat, and many recent distributions on x86 (Intel and AMD in 32-bit mode)
- Linux SUSE and Red Hat on zSeries® or mainframe
nmon tool is updated roughly every six months, or when new operating system releases are available. To place your name on the e-mail list for updates, contact Nigel Griffiths.
Use this tool together with nmon analyser (see Resources), which loads the
nmon output file and automatically creates dozens of graphs.
nmon tool is designed for AIX and Linux performance specialists to use for monitoring and analyzing performance data, including:
- CPU utilization
- Memory use
- Kernel statistics and run queue information
- Disks I/O rates, transfers, and read/write ratios
- Free space on file systems
- Disk adapters
- Network I/O rates, transfers, and read/write ratios
- Paging space and paging rates
- CPU and AIX specification
- Top processors
- IBM HTTP Web cache
- User-defined disk groups
- Machine details and resources
- Asynchronous I/O -- AIX only
- Workload Manager (WLM) -- AIX only
- IBM TotalStorage® Enterprise Storage Server® (ESS) disks -- AIX only
- Network File System (NFS)
- Dynamic LPAR (DLPAR) changes -- only pSeries p5 and OpenPower for either AIX or Linux
Also included is a new tool to generate graphs from the
nmon output and create .gif files that can be displayed on a Web site.
See the README file for more details.
Benefits of the tool
nmon tool is helpful in presenting all the important performance tuning information on one screen and dynamically updating it. This efficient tool works on any dumb screen, telnet session, or even a dial-up line. In addition, it does not consume many CPU cycles, usually below two percent. On newer machines, CPU usage is well below one percent.
Data is displayed on the screen and updated once every two seconds, using a dumb screen. However, you can easily change this interval to a longer or shorter time period. If you stretch the window and display the data on X Windows, VNC, PuTTY, or similar, the
nmon tool can output a great deal of information in one place.
nmon tool can also capture the same data to a text file for later analysis and graphing for reports. The output is in a spreadsheet format (.csv).
Installing the tool
The tool is a stand-alone binary file (a different file for each AIX or Linux version) that you can install in five seconds, probably less if you type fast. Installation is simple:
- Copy the
nmonXXX.tar.Zfile to the machine. If using FTP, remember to use binary mode.
Note: Version XXX replaces this example.
- To uncompress the file, run
- To extract the files, run
tar xvf nmonXX.tar.
- Read the README file.
- To start the
- If you are the root user, you might need to type
Extra notes for using
nmon 9 for AIX 4 only
- You must be the root user or allow regular users to read the /dev/kmem file by typing the following command (as root):
chmod ugo+r /dev/kmem
- If you want the disk statistics, then also run (as root):
chdev -l sys0 -a iostat=true
How to run the tool interactively
For running the tool interactively, read the front page of the file for a few hints. Then start the tool and use the one-key commands to see the data you want. For example, to get CPU, Memory, and Disk statistics, start
nmon and type:
How to get help information while running interactively
Additional help information
For additonal help information, try the following:
- Type the
nmon -?command for brief details.
- Type the
nmon -hcommand for full details.
- Read the README file.
How to capture the data to a file for later analysis and graphing
nmon with the -f flag. See
nmon -h for the details. But as an example, try to run
nmon for an hour capturing data snapshots every 30 seconds by using:
Â Â Â Â
nmon -f -s 30 -c 120 nmon -fT -s 30 -c 120
The second line also captures the top processes. Both of these create the output file in the current directory called: Â Â Â Â
This file is in a comma-separated values (CSV) format and can be imported into a spreadsheet directly. If you are using Lotus® 1-2-3, the file needs to be sorted. (This is not required for the Excel version of the
nmon analyser.) On AIX, follow this example:
Â Â Â Â
sort -A mymachine_311201_1030.nmon > xxx.csv
Notes to save you time:
- To load the
nmondata capture file into a spreadsheet, check the spreadsheet documentation for loading CSV data files (.csv). Many spreadsheets accept this data as just one of the possible files to load or provide an import function to do this. Many spreadsheets have a fixed number of columns and rows. I suggest you collect a maximum of 300 snapshots to avoid hitting these issues.
- When you are capturing data to a file,
nmondisconnects from the shell to ensure that it continues running, even if you log out. This means that
nmoncan appear to crash, even though it's still running in the background. To see if the process is still running, type:
ps ?ef | grep nmon
- Read the README file for more information about which version of
nmonto run on your particular operating system.
nmonVersion 10 for AIX 5 no longer uses /dev/kmem, but only public APIs. So, you don't have to chage the permissions on /dev/kmem, and there is no need to have 32- and 64-bit versions of
- For AIX 5.1, 5.2, and 5.3, use
- On AIX, don't report
lslpp -Lcq bos.?pcore dumps on AIX 5.1, about ML03 onwards. Also, WLM stats go missing after upgrading to AIX 5.2 ML5 to Nigel Griffiths, as these are AIX bugs. These are avoided by using
- Don't use Microsoft® Windows® Telnet and use a larger window than 80 x 25 characters. Many developers use VNC and PuTTY to display
nmonfrom a Windows machine -- why not do the same!
New features for
nmon on AIX Version 10
|Starting up||There is also now a small shell script called |
|N = NFS||NFS is completely new for |
|p = Partitions||This is for shared CPU partitions information -- the big p5/AIX5.3 feature.|
|C = CPU||This is for machines with 32 plus CPUs -- up to 128 logical CPUs by demand.|
|c = CPU||Details your physical CPU use -- if you are on a POWER5 with AIX 5.3 and in a shared CPU environment.|
|S = Subclass||This is for WLM subclasses -- by request.|
|a = Disk adapters||Gives you details of the disk adapter -- like their full type.|
|r = Resources||This includes your CPU speed in MHz.|
|k = Kernel||Gives some new fields.|
|L = Large pages||Gives you large-page stats -- popular with high-performance guys.|
|D = Disk||Gives you more information about your disks, disk type sizes, free, volume groups, adapter, and so forth.|
|n = Network||Gives you information about your network adapters details, MTU, and errors.|
|m = Memory||Gives you more details on where your memory is going, system (kernel) and processes, and active virtual memory.|
|-B||This is a start-up option to remove the boxes.|
Sample output for nmon 10 for AIX 5
Figure 1 below is a sample of the screen output. It shows the opening screen for AIX 5, with lots of useful information.
Figure 1. Sample output for nmon 10 for AIX 5
Figure 2 illustrates the details for CPU (this is a 4 CPU POWER5 machine with SMT switched on), memory use, kernel internal statistics, and disks statistics. Note: This logical partition (LPAR) is using six times its entitlement in half a CPU.
Figure 2. CPU details
Figure 3 shows the details of the network, NFS statistics, and journal filesystem use.
Figure 3. Network details
The details of the POWER5 shared processor micro-partitions statistics are shown in Figure 4 below.
Figure 4. LPAR details
details of the Linux version of
nmon, showing the CPU (this is a 2 CPU POWER5 machine with SMT switched on), LPAR statistics, memory use, network statistics, file system use, and disks statistics. Note: The physical CPU of this LPAR is only available with SUSE SLES9 Service Pack 1 and Red Hat EL 4 Update 1.
Figure 5. Linux version of nmon
Figure 6 shows the OS details of the machine, disk statistics (detailed mode), and the top processes.
Figure 6. Linux version of nmon continued
Obtaining the tool
The following download options are available:
- You can download nmon and its tools from IBM Wiki at http://www-941.haw.ibm.com/collaboration/wiki/display/WikiPtype/nmon.
- Check out the Performance Tools forum for nmon questions and ideas at http://www-03.ibm.com/systems/p/community/.
- "nmon analyser -- A free tool to produce AIX performance reports" (developerWorks, April 2006): Produce a wealth of report-ready graphs from nmon output.
- Check out the following IBM Redbooks for additional information on performance:
- Understanding IBM pSeries Performance and Sizing, SG24-4810-01, Febraruary 2001
- Database Performance on AIX in the DB2 UDB and Oracle Environments, SG24-5511, January 2003
- AIX 5L Performance Tools Handbook,SG24-6039, August 2003
- Check out other articles and tutorials written by Nigel Griffiths:
- "AIX 5 performance series: CPU monitoring and tuning": Browse through this article to get rid of your CPU bottlenecks and improve performance.
- Search the AIX and UNIX library by topic:
- AIX and UNIX: The AIX and UNIX developerWorks zone provides a wealth of information relating to all aspects of AIX systems administration and expanding your UNIX skills.
- New to AIX and UNIX: Visit the New to AIX and UNIX page to learn more about AIX and UNIX.
- AIX 5L™ Wiki: A collaborative environment for technical information related to AIX.
- IBM Power Systems on IBM PartnerWorld
- Safari bookstore: Visit this e-reference library to find specific technical resources.
- developerWorks technical events and webcasts: Stay current with developerWorks technical events and webcasts.
- Podcasts: Tune in and catch up with IBM technical experts.
Get products and technologies
- IBM trial software: Build your next development project with software for download directly from developerWorks.
- nmon: Download nmon and its tools.
- Participate in the developerWorks blogs and get involved in the developerWorks community.
- Participate in the AIX and UNIX forums:
- nmon questions: Check out the Performance Tools forum for nmon questions and ideas.
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