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March 21st, 2025 12:41
SNMP Thermal information not reported correctly on S4148T switches
I've set up our SNMP monitoring solution to periodically collect temperature information via oid .1.3.6.1.4.1.674.11000.5000.100.4.1.2.7 (os10ThermalSensorTable) from our S4148T switches and came across with a strange behavior happening in all of them.
Initially, I validated the values collected via SNMP against the values shown using the 'show environment' and everything matched, as expected.
After few days monitoring the devices, I notice that the values collected via SNMP weren't changing gradually. Instead, they kept the same for long periods and suddenly changed abruptly, changing multiples degrees at once.
At first, I couldn't explain why this behavior was happening, but after further tests I realized that the thermal values reported by the switch's SNMP service only were updated after running the command 'show environment' at the switch's console.
Since then, I've been executing the 'show environment' command periodically and values reported are changing in a more realistic way.
Is it a OS10 bug or is the expected behavior? Has anyone faced similar situation? How was it fixed?
Thank you in advanced.
Anderson
DELL-Charles R
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March 21st, 2025 18:42
Hello,
The switch has "thermal sensors" which measure the switch temperature. Switch temperature measurement makes sure that the switch does not overheat, for example if it is put in a hot room.
This switch temperature can be displayed in 2 ways :
1) manually using the "show environment" command in which case a trap or inform message is triggered
2) from an external Monitoring tool which connects to the switch and gets that information.
How often it connects is controlled by the "polling interval" which is configured at the Monitoring tool, not at the switch (so in a way it is not our switch problem).
Now if you what to see value getting updated more often automatically which is done via SNMP, lets say every 5 minutes. For that you have to look at the User Guide for your monitoring tool and modify the Polling Interval parameter, so that the tool "polls" or asks the switch more often to get the current temperature of the switch.
The switch always knows its temperature, but someone has to ask for it.
AndersonFerreira
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March 21st, 2025 19:32
Hello, @DELL-Charles R .
The problem isn't the pooling interval. We use Zabbix to monitoring the switches and it collects data every 5 minutes. Looking at the historical data collected was possible to see that the values collected stayed the same for hours.
Thermal data reported by the switch's SNMP service just changed after I logged in the switch console and executed the 'show environment' command.
I had to configure the cron service of each switch to execute that command periodically to be able to see more realistic variations in the values reported by the SNMP service.
Another curious thing I've observed while investigating this behavior is that although the 'show environment' somehow makes the values in SNMP to change, the same does not happen when I try to execute the /opt/dell/os10/bin/os10-show-env command.
Best regards,
Anderson