Hardware status is displayed as "unknown" for certain sensors on ESXi host

Products

• VMware vSphere ESXi

Issue/Introduction

Symptoms:
Certain sensors in ESXi host displays status as "unknown".

Environment

VMware vSphere 7.0.x
VMware vSphere ESXi 6.7
VMware vSphere ESXi 7.0.0
VMware vSphere ESXi 6.5

Cause

Sensor in below categories do not report their health status.

• Presence sensors,
• Disabled sensors,
• Sensors with no reading available,
• BIOS related,
• Event-only sensors
• Watchdog Sensors
• OEM Reserve

A change was made in vSphere 6.7 and 6.5 U2 releases to display status as "unknown".

Resolution

This is an expected behaviour in ESXi 6.5 U2 and ESXi 6.7.

Additional Information

How to identify sensor belongs to one of the above mentioned category

BIOS related sensor :Run 'esxcli hardware ipmi sdr list' command on the host. BIOS related sensor will have Entity-Instance column value "34.1"

Presence sensor : Run 'esxcli hardware ipmi sdr list' command and check below information for all sensors

• Base Unit should be either 'enabled-discrete' or 'available-discrete'
• Or Sensor Type should be 'Entity Presence'

Note : This data available only in 6.7 not in 6.5 U2, from 6.7 U1 it is filtered.

Disabled or No reading : Run /bin/cim-diagnostic.sh script.
In OMC_RawIpmiSensor class instances, check below fields for each entry:
ReadingStateUnavailable = true -> No reading sensors
Scanning disabled = true -> Disabled sensors

Event-only sensor : Use ipmitool and run below command:
'ipmitool sdr elist all'
 Check last column for 'Event-Only'entry.

Watchdog Sensor:
Running esxcli hardware ipmi sdr list command shows output  watchdog sensors category as "Watchdog"
eg:
Sensor              Health    SEL entries  Current reading   ID           Last updated  Category  Type/Unit
Other---0.35.0.212   Unknown   0               0              0.35.0.212      Unknown    Watchdog  Unknown