Health Checks

Health checks allow you to query different aspects of your system to be alerted of potential issues. A good example is checking the SMART attributes of a hard drive.

Permissions

Some of these checks require elevated permissions, more commonly in Linux to the sudoers file.

Nagios Plugins / NRPE / Linux

The following KB articles explain how to add sudoers entries and to configure NRPE to execute checks using sudo.

Warning: This Plugin Must Be Either Run As Root Or Setuid

NRPE: Unable To Read Output (The Plugin Requires "sudo" Privileges)

Disk Health

Disk health checks can be queried by checking the SMART status.

Nagios Plugins

The check_ide_smart plugin is part of Nagios Plugins.

Command:

/usr/local/nagios/libexec/check_ide_smart -d /dev/sda

Output:

OK - Operational (15/15 tests passed)

NCPA

NPCA does not includes a SMART disk module.

NSClient++ via check_nt

NSClient++ does not includes a SMART disk module.

NSClient++ via check_nrpe

NSClient++ does not includes a SMART disk module.

WMI

Check WMI Plus includes a checksmart module.

Command:

./check_wmi_plus.pl -H 10.25.11.2 -u wmiagent -p Str0ngP@ssw0rd -m checksmart

Output:

Overall Status - OK -  Found 1 Disks(s), 1 OK and 0 failing |'WD-WXXXXXXXXXXX_Reallocated_Sector_Count'=0; 'WD-WXXXXXXXXXXX_Power_On_Hours'=12401;
'WD-WXXXXXXXXXXX_Power_Cycle_Count'=441; 'WD-WXXXXXXXXXXX_Temperature'=36; 'WD-WXXXXXXXXXXX_Current_Pending_Sector'=0; 'WD-WXXXXXXXXXXX_Offline_Uncorrectable'=0;
OK - Dev#0, WDC WD50000000-0000001, Serial#WD-WXXXXXXXXXXX, PredictFailure=False, Temperature=36

SNMP

Using SNMP to check disk health is possible but requires some additional work that is not possible to cover in this KB article.

Sensors

Sensor data is usually attributed to temperature and fan data.

Nagios Plugins

The check_sensors plugin is part of Nagios Plugins. It uses the program sensors/lm_sensors to interrogate the system hardware like CPU and Motherboard, this can report temperature and fan alerts.

Command:

./check_sensors

Output:

SENSOR CRITICAL - Sensor alarm detected!

NCPA

NPCA does not include any sensor capabilities.

NSClient++ via check_nt

NSClient++ does not include any sensor capabilities.

NSClient++ via check_nrpe

NSClient++ does not include any sensor capabilities.

WMI

Check WMI Plus does not include any sensor capabilities.

SNMP

The check_snmp plugin allows you to target any type of sensor using SNMP. Here is an example of checking the internal temperature sensor on an APC UPS:

Command:

./check_snmp -H 10.25.19.2 -C box293 -P 2c -o PowerNet-MIB::upsHighPrecBatteryTemperature.0 -c 450

Output:

SNMP OK - 391 | PowerNet-MIB::upsHighPrecBatteryTemperature.0=391;;450;

The value the UPS returns is in tenths of degrees Celsius. If you wanted to make this easier to read you would need to create a wrapper script to manipulate the results.

Final Thoughts

For any support related questions please visit the Nagios Support Forums at:

http://support.nagios.com/forum/