All-purpose admin tool
Peak Performance
Administrators often assume that if all nodes are functioning, the system is fine. However, a common problem is poor or unexpected application performance. In this case, you need a simple tool to help you understand what's happening on the nodes: nmon.
The most common user complaint I receive is poor or unexpected performance by a user application, so I've been spending some time looking at tools that can help me understand what is happening on a server. A good place to start is with simple command-line applications that watch overall system performance. I chose command-line tools because I don't always have a nice GUI to the node, and sometimes I am left with just a simple SSH connection or a crash cart (the nodes likely don't have graphics cards). In this article, I'm going to examine a comprehensive tool that provides a quick glance at node performance from many perspectives (i.e., CPU, network, disk). The tool is called nmon [1].
Nmon Overview
Nmon is short for "Nigel's Monitor" and is a command-line tool that presents performance information about the system to the user. It started in the AIX world but has migrated to other *nix systems, including Linux. Nmon has lots of options for monitoring different aspects of the system, including:
- Machine (system) information
- CPU stats
- Memory stats
- Virtual memory stats
- Kernel internal stats
- Network stats (and errors)
- NFS information
- Disk I/O stats (and graphs)
- Disk busy information (Disk I/O map)
- Partition disk I/O stats
- Logical partition disk I/O stats
[...]
Buy this article as PDF
(incl. VAT)
Buy Linux Magazine
US / Canada
UK / Australia