Recommended Tools:  Nmon Monitoring Tool for Linux

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Affected Roles:  Administrator, Owner

Related Digital Watchdog VMS Apps:  DW Spectrum® IPVMS

Last Edit:  January 21, 2022

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Nmon Command Line Utility

The Nmon command line utility is an optional tool for performance monitoring, benchmarking, or system administrator tuning.  It is fully interactive and can help Linux users with the necessary commands as needed.

Some included monitoring options include:

• CPU performance
• Memory performance
• Network performance
• Storage disks
• File systems
• NFS
• Top processes
• Resources
• Power micro-partition

This article will outline how to install and use the Nmon monitoring tool for Linux.

**NOTE:  This is an optional, supplemental tool that can be installed for Linux-based DW Spectrum® Servers.  DW Blackjack® Servers shipping with Ubuntu 18.04 will come pre-loaded with this tool.

Supported/Affected Devices:

• DW Blackjack® Tower Server Series (Linux)
• DW Blackjack® Rack Server Series (Linux)
• DW Blackjack® E-Rack Series (Linux)
• DW Blackjack® P-Rack Series (Linux)
• DW Blackjack® Cube Series (Linux)
• DW Blackjack® Bolt Series

Enabling Repository Access

By default, DW Blackjack® Servers have OS updates disabled to prevent unexpected operating issues that may occur from auto-updates.

As so, Servers using Ubuntu have repository access disabled by default as well.      

To install the Nmon utility, the repository will need to be made accessible to acquire the installation files.  If Nmon is already installed and you are just seeking operating instructions, you can skip to the Using Nmon to Monitor LinuxOS Performance section.

**DISCLAIMER:  Please be aware that DW Blackjack® Servers have OS updates and repository access disabled by default.  Altering a DW Blackjack® Server’s OS configuration from default settings are performed at the owner’s risk.

**NOTE:  When using the Linux command line, be aware that commands are case-sensitive.  Press the ENTER key after each command, unless otherwise instructed.

Add Repository Access

To restore repository access:

1. Open the Terminal program.  You can do this by using the Search function in the system Unity menu.

Alternatively, you can simultaneously press the Ctrl+Alt+T keys on the keyboard to launch the Terminal program.

2. The Terminal window will display.

To add the repository, use the command:

sudo add-apt-repository “deb http://us.archive.ubuntu.com/ubuntu/ xenial universe multiverse”

3. You will be prompted to enter the superuser password.  Use the root admin password (will not display):

Dw5pectrum

**NOTE:  For older DW Blackjack units purchased prior to June 18, 2021, the previously utilized default Linux OS login was “admin/admin”.

4. Follow adding the repository by adding the main repository as well:

sudo add-apt-repository “deb http://us.archive.ubuntu.com/ubuntu/ xenial main universe multiverse”

5. Next, to download OS updates, use the command:

sudo add-apt-repository “deb http://us.archive.ubuntu.com/ubuntu xenial-updates universe multiverse”

Follow with command:

sudo apt-get update

6. Allow the system to finish fetching the data packages.

You may enter the command again to double-check that the available updated data packages have been obtained.

sudo apt-get update

Repairing Broken Repository Dependencies

If an error occurs while attempting to add the repository, there is a chance that the atp-get command may be encountering issues when retrieving third-party dependencies.  For example, such an error may display as:

The following packages have unmet dependencies:

   E: Unable to correct problems, you have held broken packages.

If you encounter an issue with repository access or package corruption, refer to Repairing Broken Repository Dependencies for Ubuntu Servers for troubleshooting help.

Installing the Nmon Utility

To install Nmon command line utility:

1. Open the Terminal program.  You can do this by using the Search function in the system Unity menu.

Alternatively, you can simultaneously press the Ctrl+Alt+T keys on the keyboard to launch the Terminal program.

2. The Terminal window will display.

Log in as the root Administrator with the following command:

sudo su

3. When prompted, use the root admin password (will not display):

Dw5pectrum

**NOTE:  For older DW Blackjack units purchased prior to June 18, 2021, the previously utilized default Linux OS login was “admin/admin”.

4. Install the Nmon utility from the default repository using the command:

sudo apt-get install nmon

5. Allow the utility to download and install.

Using Nmon to Monitor Linux OS Performance

To launch the Nmon utility, use the command:

nmon

As a result, the Nmon utility will run as an interactive interface.

Nmon Controls

The Nmon command line utility operates completely through toggles and text.

Use the following keys to toggle the performance statistics ON or OFF.