Forum Discussion
Cirruschecking the fan status on the device.
Understanding how the threshold system works for sensor monitoring on your F5 device is crucial for maintaining the health and performance of the system. The thresholds determine when the system will flag a sensor reading as normal, warning, or critical. Here’s a detailed explanation of how this typically works:
Threshold System Overview
- Sensor Measurement: The system continuously monitors various sensors, such as fan speeds, temperatures, voltages, etc.
- Thresholds: Each sensor has predefined thresholds that specify what values are considered normal, warning, or critical. These thresholds can include:
- Lower Critical (LC): The value below which the sensor reading is considered critical.
- Lower Warning (LW): The value below which the sensor reading is considered a warning.
- Upper Warning (UW): The value above which the sensor reading is considered a warning.
- Upper Critical (UC): The value above which the sensor reading is considered critical.
- Hysteresis: This is a value used to prevent frequent toggling of the sensor status. It creates a buffer zone so that minor fluctuations around the threshold do not cause constant status changes.
Example of Thresholds
For a fan speed sensor:
- LC: 500 RPM (below this is critical)
- LW: 750 RPM (below this is warning)
- UW: 5000 RPM (above this is warning)
- UC: 5500 RPM (above this is critical)
View Current Thresholds:
tmsh show /sys hardware
ModeratorHI Zen_Y,
Let me try to breakdown the terms found in the command output.
The CRIT (Critical) value and Hyst (Hysteresis) value serve different purposes in system monitoring and are not directly compared to determine if a component is in a critical state. Instead, the critical status (CRIT) is typically determined based on predefined thresholds or conditions set for the component, independent of the hysteresis value.
- CRIT (Critical):
- The CRIT status indicates that a component's current measurement (e.g., fan speed, voltage) is outside the acceptable operational range and is in a critical state. This typically means that the component is either failing or performing in a way that could lead to system instability or damage.
- Therefore, the actual threshold for what constitutes a critical state is predefined by the system's monitoring policies and can vary depending on the component and its specifications.
- Hyst (Hysteresis):
- Hysteresis is a buffer range used to prevent frequent toggling or cycling of a component. For example, in temperature control, hysteresis might define how much the temperature needs to decrease below a set threshold before a cooling fan turns off, thus avoiding rapid on/off cycles.
- The hysteresis value helps stabilize the operation by introducing a delay or buffer before triggering actions like turning on/off fans or other controls.
In the output you provided, the "CRIT" status indicates that the current value (Cur) of the component is outside the predefined acceptable range, triggering a critical alert.
- For example, the 1/bld_cpu_fan has a current speed of 4928 RPM but is marked as "CRIT," indicating that this speed is outside the acceptable operational range for the CPU fan.
The hysteresis (Hyst) value, in this context, serves to provide a buffer for operational changes but does not directly influence whether a component is marked as critical. The critical status is determined based on whether the current value exceeds the predefined thresholds, not in comparison to the hysteresis value.
If you'd like F5 TAC to take a look at the fan reading and examine if there's an issue, you can submit a support case to F5.
Cheers,
Mo
