README.md

Fan Monitor Configuration File

Table of Contents

• Overview
• Data Format
• Example
• System Config Location
• Contents
• Validation
• Firmware Updates
• Loading and Reloading

Overview

The phosphor-fan-monitor application is controlled by a configuration file (config file) to manage the Functional property's state on the xyz.openbmc_project.State.Decorator.OperationalStatus interface for fan inventory objects. The config file defines the method to use in determining the functional state and the logging of errors for each fan within a machine. It also provides the ability to adjust the determination of a fan being non-functional due to fan hardware limitations.

Data Format

The config file is written using the JSON (JavaScript Object Notation) data format and can be created using a text editor.

Example

See config.json.

System Config Location

The config file name is config.json.

Supported Directory

/usr/share/phosphor-fan-presence/monitor/

The supported version of the config file is installed under this read-only directory location as part of the firmware image install. This is where the config file will be loaded from when no overriding config file exists.

Default Location

Where a single config file for 1-or-more system types can be used, the config file can be located at the base of the supported directory.

i.e.) /usr/share/phosphor-fan-presence/monitor/config.json

Compatible System Type Location

The config file location can also be based on a system type. This is necessary where more than one type of machine is supported in a single BMC firmware image and those system types can not share a common config file.

A system type sub-directory can be obtained from the IBMCompatibleSystem D-Bus interface's Names property. The Names property contains a list of one or more compatible system types, ordered from most specific to the most general.

Example:

• ibm,rainier-2u
• ibm,rainier

The phosphor-fan-monitor application then traverses the supported directory, appending each compatible system type entry as a sub-directory from most specific to most general until the config file is found.

Example:

1. /usr/share/phosphor-fan-presence/monitor/ibm,rainier-2u/
   • (directory/config file does not exist)
2. /usr/share/phosphor-fan-presence/monitor/ibm,rainier/config.json
   • (config file found)

If a config file is not found and the machine is powered on, an error is logged and phosphor-fan-monitor application terminates preventing the machine from successfully powering on.

Override Directory

/etc/phosphor-fan-presence/monitor/

A different version of the config file can be loaded by placing it into this writable directory location. This avoids the need to build and install a new firmware image on the BMC when changing the configuration, such as for testing purposes.

The override directory may not exist on the BMC, therefore to be able to use an overriding config file it must be created using the following command:

mkdir -p /etc/phosphor-fan-presence/monitor

Search Order

The phosphor-fan-monitor application will search for the config file at the directory locations in the following order:

1. Override directory
2. Supported directory
   • Default location
   • Compatible System Type location

Contents

Structure

The config file consists of an array of fan objects that define how to monitor their functional state and what fault handling should occur. Fault handling includes creating error logs and/or powering off the system for a configured number of fans that are missing or nonfunctional.

{
  "fans": [
    {
      ...
    },
    .
    .
    .
  ],
  "sensor_trust_groups": [
    {
      ...
    },
    .
    .
    .
  ],
  "fault_handling": {
    ...
  }
}

Syntax

Fan object attributes: (Required unless otherwise noted)

• inventory
• method - *Optional, default = "timebased"
• deviation
• num_sensors_nonfunc_for_fan_nonfunc - Optional, default = 0
• monitor_start_delay - Optional, default = 0
• fan_missing_error_delay - Optional
• nonfunc_rotor_error_delay - Optional
• set_func_on_present - Optional, default = false
• sensors

Trust group attributes: (Optional)

• class
• group

Fault handling attributes: (Optional)

• num_nonfunc_rotors_before_error - Optional, default = 1
• power_off_config - Optional

*-See attribute page for more details

Comments

The JSON data format does not support comments. However, an optional comments attribute name can be used to annotate any specific entry of the JSON configuration. It is suggested that the value of this comments attribute be an array of strings for comments containing line breaks. All comments objects are ignored when the JSON configuration is processed.

Note: Only 1 comments object can exist at any given 'layer' of the configuration hierarchy

Example:

{
  "comments": [
   "Fan monitoring configuration of X-number of fans",
   "Where some fan sensors are not trusted at times",
   "Faults create error logs and power off the system"
  ],
  "fans": [
    {
      "comments": "Monitor this fan",
      ...
    },
    .
    .
    .
  ],
  "sensor_trust_groups": [
    {
      "comments": "Only trust these fan sensors when all are not zero",
      ...
    },
    .
    .
    .
  ],
  "fault_handling": {
    "comments": "Log errors and power off the system",
    ...
  }
}

Validation

TBD

Firmware Updates

When a new firmware image is installed on the BMC, it will update the config file in the standard directory.

The override directory will not be modified by a firmware update. If a config file exists in the override directory, it will continue to be used as the fan presence configuration instead of the config file located under the appropriate location within the supported directory.

Loading and Reloading

The config file is loaded when the phosphor-fan-monitor application starts.

To force the application to reload the config file, use the following command on the BMC:

systemctl kill -s HUP phosphor-fan-monitor@0.service

To confirm which config file was loaded, use the following command on the BMC:

journalctl -u phosphor-fan-monitor@0.service | grep Loading