C.5. Linux

The probes in this section monitor essential aspects of your Linux systems, from CPU usage to virtual memory. Apply them to mission-critical systems to obtain warnings prior to failure.

Unlike other probe groups, which may or may not require the Red Hat Network Monitoring Daemon, every Linux probe requires that the rhnmd daemon be running on the monitored system.

C.5.1. Linux::CPU Usage

The Linux::CPU Usage probe monitors the CPU utilization on a system and collects the following metric:

Requirements — The Red Hat Network Monitoring Daemon (rhnmd) must be running on the monitored system to run this probe.

FieldValue
Timeout*15
Critical Maximum CPU Percent Used 
Warning Maximum CPU Percent Used 

Table C-15. Linux::CPU Usage settings

C.5.2. Linux::Disk IO Throughput

The Linux::Disk IO Throughput probe monitors a given disk and collects the following metric:

To obtain the value for the required Disk number or disk name field, run iostat on the system to be monitored and see what name has been assigned to the disk you desire. The default value of 0 usually provides statistics from the first hard drive connected directly to the system.

Requirements — The Red Hat Network Monitoring Daemon (rhnmd) must be running on the monitored system to execute this probe. Also, the Disk number or disk name parameter must match the format visible when the iostat command is run. If the format is not identical, the configured probe enters an UNKNOWN state.

FieldValue
Disk number or disk name*0
Timeout*15
Critical Maximum KB read/second 
Warning Maximum KB read/second 
Warning Minimum KB read/second 
Critical Minimum KB read/second 
Critical Maximum KB written/second 
Warning Maximum KB written/second 
Warning Minimum KB written/second 
Critical Minimum KB written/second 

Table C-16. Linux::Disk IO Throughput settings

C.5.3. Linux::Disk Usage

The Linux::Disk Usage probe monitors the disk space on a specific file system and collects the following metrics:

Requirements — The Red Hat Network Monitoring Daemon (rhnmd) must be running on the monitored system to execute this probe.

FieldValue
File system*/dev/hda1
Timeout*15
Critical Maximum File System Percent Used 
Warning Maximum File System Percent Used 
Critical Maximum Space Used 
Warning Maximum Space Used 
Warning Minimum Space Available 
Critical Minimum Space Available 

Table C-17. Linux::Disk Usage settings

C.5.4. Linux::Inodes

The Linux::Inodes probe monitors the specified file system and collects the following metric:

An inode is a data structure that holds information about files in a Linux file system. There is an inode for each file, and a file is uniquely identified by the file system on which it resides and its inode number on that system.

Requirements — The Red Hat Network Monitoring Daemon (rhnmd) must be running on the monitored system to execute this probe.

FieldValue
File system*/
Timeout*15
Critical Maximum Inodes Percent Used 
Warning Maximum Inodes Percent Used 

Table C-18. Linux::Inodes settings

C.5.5. Linux::Interface Traffic

The Linux::Interface Traffic probe measures the amount of traffic into and out of the specified interface (such as eth0) and collects the following metrics:

Requirements — The Red Hat Network Monitoring Daemon (rhnmd) must be running on the monitored system to execute this probe.

FieldValue
Interface* 
Timeout*30
Critical Maximum Input Rate 
Warning Maximum Input Rate 
Warning Minimum Input Rate 
Critical Minimum Input Rate 
Critical Maximum Output Rate 
Warning Maximum Output Rate 
Warning Minimum Output Rate 
Critical Minimum Output Rate 

Table C-19. Linux::Interface Traffic settings

C.5.6. Linux::Load

The Linux::Load probe monitors the CPU of a system and collects the following metric:

Requirements — The Red Hat Network Monitoring Daemon (rhnmd) must be running on the monitored system to execute this probe.

FieldValue
Timeout*15
Critical CPU Load 1-minute average 
Warning CPU Load 1-minute average 
Critical CPU Load 5-minute average 
Warning CPU Load 5-minute average 
Critical CPU Load 15-minute average 
Warning CPU Load 15-minute average 

Table C-20. Linux::Load settings

C.5.7. Linux::Memory Usage

The Linux::Memory Usage probe monitors the memory on a system and collects the following metric:

You can also include the reclaimable memory in this metric by entering yes or no in the Include reclaimable memory field.

Requirements — The Red Hat Network Monitoring Daemon (rhnmd) must be running on the monitored system to execute this probe.

FieldValue
Include reclaimable memoryno
Timeout*15
Warning Maximum RAM Free 
Critical Maximum RAM Free 

Table C-21. Linux::Memory Usage settings

C.5.8. Linux::Process Counts by State

The Linux::Process Counts by State probe identifies the number of processes in the following states:

Requirements — The Red Hat Network Monitoring Daemon (rhnmd) must be running on the monitored system to execute this probe.

FieldValue
Timeout*15
Critical Maximum Blocked Processes 
Warning Maximum Blocked Processes 
Critical Maximum Defunct Processes 
Warning Maximum Defunct Processes 
Critical Maximum Stopped Processes 
Warning Maximum Stopped Processes 
Critical Maximum Sleeping Processes 
Warning Maximum Sleeping Processes 
Critical Maximum Child Processes 
Warning Maximum Child Processes 

Table C-22. Linux::Process Counts by State settings

C.5.9. Linux::Process Count Total

The Linux::Process Count Total probe monitors a system and collects the following metric:

Requirements — The Red Hat Network Monitoring Daemon (rhnmd) must be running on the monitored system to execute this probe.

FieldValue
Timeout*15
Critical Maximum Process Count 
Warning Maximum Process Count 

Table C-23. Linux::Process Count Total settings

C.5.10. Linux::Process Health

The Linux::Process Health probe monitors user-specified processes and collects the following metrics:

Specify the process by its command name or process ID. (PID). Entering a PID overrides the entry of a command name. If no command name or PID is entered, the error Command not found is displayed and the probe will be set to a CRITICAL state.

Requirements — The Red Hat Network Monitoring Daemon (rhnmd) must be running on the monitored system to execute this probe.

FieldValue
Command Name 
Process ID (PID) file 
Timeout*15
Critical Maximum CPU Usage 
Warning Maximum CPU Usage 
Critical Maximum Child Process Groups 
Warning Maximum Child Process Groups 
Critical Maximum Threads 
Warning Maximum Threads 
Critical Maximum Physical Memory Used 
Warning Maximum Physical Memory Used 
Critical Maximum Virtual Memory Used 
Warning Maximum Virtual Memory Used 

Table C-24. Linux::Process Health settings

C.5.11. Linux::Process Running

The Linux::Process Running probe verifies that the specified process is functioning properly. It counts either processes or process groups, depending on whether the Count process groups checkbox is selected.

By default, the checkbox is selected, thereby indicating that the probe should count the number of process group leaders independent of the number of children. This allows you, for example, to verify that two instances of the Apache HTTP Server are running regardless of the (dynamic) number of child processes. If it is not selected, the probe conducts a straightforward count of the number of processes (children and leaders) matching the specified process.

Specify the process by its command name or process ID. (PID). Entering a PID overrides the entry of a command name. If no command name or PID is entered, the error Command not found is displayed and the probe enters a CRITICAL state.

Requirements — The Red Hat Network Monitoring Daemon (rhnmd) must be running on the monitored system to execute this probe.

FieldValue
Command name 
PID file 
Count process groups(checked)
Timeout*15
Critical Maximum Number Running 
Critical Minimum Number Running 

Table C-25. Linux::Process Running settings

C.5.12. Linux::Swap Usage

The Linux::Swap Usage probe monitors the swap partitions running on a system and reports the following metric:

Requirements — The Red Hat Network Monitoring Daemon (rhnmd) must be running on the monitored system to execute this probe.

FieldValue
Timeout*15
Warning Minimum Swap Free 
Critical Minimum Swap Free 

Table C-26. Linux::Swap Usage settings

C.5.13. Linux::TCP Connections by State

The Linux::TCP Connections by State probe identifies the total number of TCP connections, as well as the quantity of each in the following states:

This probe can be helpful in finding and isolating network traffic to specific IP addresses or examining network connections into the monitored system.

The filter parameters for the probe let you narrow the probe's scope. This probe uses the netstat -ant command to retrieve data. The Local IP address and Local port parameters use values in the Local Address column of the output; the Remote IP address and Remote port parameters use values in the Foreign Address column of the output for reporting.

Requirements — The Red Hat Network Monitoring Daemon (rhnmd) must be running on the monitored system to execute this probe.

FieldValue
Local IP address filter pattern list 
Local port number filter 
Remote IP address filter pattern list 
Remote port number filter 
Timeout*15
Critical Maximum Total Connections 
Warning Maximum Total Connections 
Critical Maximum TIME_WAIT Connections 
Warning Maximum TIME_WAIT Connections 
Critical Maximum CLOSE_WAIT Connections 
Warning Maximum CLOSE_WAIT Connections 
Critical Maximum FIN_WAIT Connections 
Warning Maximum FIN_WAIT Connections 
Critical Maximum ESTABLISHED Connections 
Warning Maximum ESTABLISHED Connections 
Critical Maximum SYN_RCVD Connections 
Warning Maximum SYN_RCVD Connections 

Table C-27. Linux::TCP Connections by State settings

C.5.14. Linux::Users

The Linux::Users probe monitors the users of a system and reports the following metric:

Requirements — The Red Hat Network Monitoring Daemon (rhnmd) must be running on the monitored system to execute this probe.

FieldValue
Timeout*15
Critical Maximum Users 
Warning Maximum Users 

Table C-28. Linux::Users settings

C.5.15. Linux::Virtual Memory

The Linux::Virtual Memory probe monitors the total system memory and collects the following metric:

Requirements — The Red Hat Network Monitoring Daemon (rhnmd) must be running on the monitored system to execute this probe.

FieldValue
Timeout*15
Warning Minimum Virtual Memory Free 
Critical Minimum Virtual Memory Free 

Table C-29. Linux::Virtual Memory settings