Virtualized Fan Speed Measurement in Server Blade Enclosures
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Solution Overview
Problem
In server blade enclosures, acquiring the desired fan speed from devices to effectively manage cooling without modifying server firmware is challenging, as existing solutions require complex communication channels.
Innovation Solution
The implementation of a virtualized fan speed measurement system using a server enclosure manager, CAN bus microcontroller, and analog low-pass filter allows for the extraction and regulation of fan speed without firmware modification, enabling shared fans to meet cooling needs by converting PWM signals to DC voltage and reconstructing PWM signals for fan speed control.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If complex communication channels like IPMI over Ethernet are used to communicate desired fan speed, then fan speed control capability is improved, but device complexity and implementation difficulty increase
Solution Approach 1:
The patent introduces a baseboard management controller (BMC) as an intermediary device that simplifies fan speed control. The BMC receives desired fan speed from the server management interface and communicates with the fan controller through standardized interfaces, eliminating the need for complex direct communication channels like IPMI over Ethernet between all components.
Solution Approach 2:
The BMC serves multiple functions including fan speed control, temperature monitoring, and system management. By consolidating these functions in a single controller, the system reduces overall complexity while maintaining comprehensive control capabilities without requiring separate specialized communication channels for each function.
2Measurement precision
If firmware modification is required to acquire desired fan speed, then measurement precision is improved, but ease of manufacture and deployment worsen
Solution Approach 1:
The server itself provides the desired fan speed information through its existing management interfaces without requiring external firmware modifications. The BMC interfaces with the server's built-in management capabilities to obtain fan speed requirements, allowing the server to serve its own thermal management needs without external intervention or firmware changes.
Solution Approach 2:
Instead of modifying server firmware to extract fan speed information, the system uses the BMC to create a virtualized copy of the fan speed control interface. The BMC replicates the necessary control functionality through software abstraction, allowing accurate fan speed acquisition without altering the original server firmware.
3Adaptability or versatility
If shared fans are used to cool multiple devices, then device versatility is improved, but temperature control precision worsens
Solution Approach 1:
The system dynamically adjusts fan speed based on real-time temperature readings from multiple devices. The BMC continuously monitors temperature conditions and adjusts the shared fan's speed accordingly, allowing a single fan to adaptively serve multiple devices with different thermal requirements. This dynamic control maintains temperature precision despite the shared cooling resource.
Solution Approach 2:
The system implements feedback control by continuously monitoring temperatures of multiple devices and adjusting fan speed based on the most critical thermal condition. The BMC receives temperature data from various devices, processes this information, and adjusts fan operation to maintain optimal temperatures across all devices, ensuring precise temperature control through closed-loop feedback.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
This solution enables efficient fan speed regulation within server blade enclosures without modifying server firmware, ensuring optimal cooling by accurately determining and communicating desired fan speeds across the enclosure.
Implementation Method 1
analog low-pass filter receives a PWM signal... converting the PWM signal to a DC voltage
Data Source
AI summary
Example implementations relate to virtualizing fan speed. For example, a system for virtualizing fan speed may include a server enclosure manager connected to a controller area network (CAN) bus, the server enclosure manager to regulate a speed of a fan in a server blade enclosure; and a CAN bus microcontroller connected to the CAN bus. The CAN bus microcontroller may receive a direct current (DC) voltage from an analog low-pass filter, determine a fan speed of the fan corresponding to the received DC voltage, and report the determined fan speed to the enclosure manager.