Patent Application
20130242504
Computer systems or servers, at a datacenter or other location, may be rack-mounted. Each rack (e.g., Electronics Industry Association standard racks) may house a number of computer systems or servers. The components of each computer system may dissipate significant amounts of heat during operation. Each computer system is typically cooled by fans that move cooling fluid, e.g., air, conditioned air, etc., across the heat dissipating components.
For a detailed description of various examples of the invention, reference will now be made to the accompanying drawings in which:
Certain terms are used throughout the following description and claims to refer to particular system components. As one skilled in the art will appreciate, computer companies may refer to a component by different names. This document does not intend to distinguish between components that differ in name but not function. In the following discussion and in the claims, the terms “including” and “comprising” are used in an open-ended fashion, and thus should be interpreted to mean “including, but not limited to . . . .” Also, the term “couple” or “couples” is intended to mean either an indirect, direct, optical or wireless electrical connection. Thus, if a first device couples to a second device, that connection may be through a direct electrical connection, through an indirect electrical connection via other devices and connections, through an optical electrical connection, or through a wireless electrical connection. The recitation “based on” is intended to mean “based at least in part on.” Therefore, if X is based on Y, X may be based on Y and any number of additional factors.
The following discussion is directed to various implementations of a cooling system that employs individually positionable louvers to direct cooling fluid to an electronic assembly. The principles disclosed have broad application, and the discussion of any implementation is meant only to illustrate that implementation, and not intended to intimate that the scope of the disclosure, including the claims, is limited to that implementation.
Servers and other electronic assemblies are generally cooled using fans to move cool air across heat dissipating components. Data centers supporting a large number of servers can employ thousands of fans. Such systems are subject to a number of disadvantages. For example, fan inefficiencies accumulate as the number of fans increase, and fans always consume some power because they must be run at at least a nominal rate to prevent leakage current even when no cooling is needed.
The systems disclosed herein employ flow restrictors, such as louvers, to control airflow across server components. The flow restrictors can directly replace fans and be operated by a fan controller, and unlike fans, the flow restrictors do not present cumulative inefficiencies. Further, use of flow restrictors reduces system power consumption because the flow restrictors consume power only when changing position, and the power consumed is not dependent on the rate of airflow as with fans. Additionally, in some implementations, the flow restrictors require less space than fans.
The server 104 includes an enclosure 114, a plurality of louvers 112 or other airflow restrictors, a thermal controller 106, thermal sensors 108, and heat generating components 110. The louvers 112 are slats, blades, fins, or the like that change position about an axis to vary the size of an air passage and/or the direction of airflow. The heat generating components may be, for example, electronic components, such as processor(s), memories, and/or various other integrated circuits, semiconductor devices, etc. that dissipate heat while operating.
The thermal sensors 108 are distributed about the interior of the server 104 to provide measurement of temperatures across different regions of the interior of the server 104. The thermal sensors 108 may include any type of suitable temperature sensor, and may be integrated into or separate from any electronic component included in the server 104. For example, a temperature sensor 108 may integrated with a processor and/or provided as a discrete device. While three temperature sensors 108 are illustrated in the server 104 as a matter of convenience, in practice, the server 104 may include two or more thermal sensors 108.
The thermal sensors 108 are coupled to a thermal controller 106. The thermal controller 106 controls the positioning of the louvers 112 in accordance with the temperature measurements provided by the thermal sensors 108 and/or other relevant information provided by the server 104. The thermal controller 106 receives temperature measurements from the thermal sensors 108, and determines from the measurements a level of cooling needed for each of multiple regions of the server 104, where the regions correspond to areas having a temperature measured by one or more of the thermal sensors 108. For example, one thermal region of the server 104 may be dedicated to a processor, and another thermal region of the server 104 may be dedicated to memory, etc.
The thermal controller 106 may include a processor that executes instructions retrieved from a computer-readable medium. Suitable processors may include, for example, one or more general-purpose microprocessors, digital signal processors, microcontrollers, or other devices capable of executing instructions retrieved from a computer-readable storage medium. Processor architectures generally include execution units (e.g., fixed point, floating point, integer, etc.), storage (e.g., registers, memory, etc.), instruction decoding, peripherals (e.g., interrupt controllers, timers, direct memory access controllers, etc.), input/output systems (e.g., serial ports, parallel ports, etc.) and various other components and sub-systems. In some implementations, the thermal controller 106 may be implemented via a server management system, such as an Integrated Lights-Out Baseboard Management Computer.
A processor may store data in and execute instructions retrieved from a non-transitory computer-readable storage medium. A non-transitory computer-readable storage medium may include volatile storage such as random access memory, non-volatile storage (e.g., a hard drive, an optical storage device (e.g., CD or DVD), FLASH storage, read-only-memory), or combinations thereof. In some implementations, a storage medium may be local to the processor. In other implementations, storage may be remote from the processor accessed via a network.
The thermal controller 106 generates signals that control the positions of the louvers 112. Some implementations of the thermal controller 106 control the position of each louver 112 individually. The thermal controller 106 may generate signals that can be used to control the rotation rate of fans, i.e., the thermal controller 106 may be a fan controller. For example, the thermal controller 106 may generate pulse width modulated (PWM) signals, wherein the duty cycle of each signal corresponds to the rotation rate of a fan used to cool a portion of the server. The louvers 112 may replace fans in the server 104, and the louvers 112 may apply the PWM fan control signals generated by the thermal controller 106 to determine louver position. For example, the degree to which a louver 112 is open may correspond to the duty cycle of the PWM fan control signal. Accordingly, in some implementations, a louver 112 may move to the closed position 112B (blocking airflow therethrough) based on a 0% duty cycle PWM fan control signal and move to the fully open position 112C based on a 100% duty cycle PWM fan control signal.
The thermal controller 106 may individually position the louvers 112 to provide a needed level of flow of cooled airflow to each region of the server 104, and may also position the louvers 106 to direct cooled airflow within the server 104. For example, the positioning of the louvers 112A may direct cooled airflow to region 116 of the server 104 rather than region 118.
The thermal controller 106 also receives server information 202 from various components within the server 104. The server information 202 includes non-temperature measurement information that is indicative of a need for cooling in a particular region of the server 104. For example, the server information 202 may include clock rate information provided by a processor of the server 104, bus utilization information, power consumption information, etc. that may be indicative of the level of cooling needed in a region of the server 104. The thermal controller 106 may position the louvers 112 based on the server information 202.
Based on the temperature measurements 208 provided by the thermal sensors 108 and/or the server information 202 indicative of needed level, degree, or amount of cooling, the thermal controller 106 generates the control signals 204. The control signals 204 control louver motors 206 that move the louvers 112. The louver motors 206 may be any type of actuators that can change the position of the louvers 112. For example, a louver motor 206 may be a stepper motor used in conjunction with a shaft position encoder to position a louver 112 and feedback louver position information to the thermal controller 106. In some implementations, each louver 112 is controlled by a separate and distinct louver motor 206. As explained above, the thermal controller 106 may be a fan controller, and the control signals 204 maybe fan speed control signals, such as PWM signals having a duty cycle proportional to fan speed. The louver motors 206 and/or circuitry associated therewith may determine a requested louver position based on the fan control signals and/or convert the fan control signals into signals that move the louvers 112 into a requested position.
In block 302, the server 104 is operating. Components of the server 104 are dissipating heat, and cooling is provided to maintain the components of the server 104 within a predetermined operating temperature range. The inlets of the server 104 are coupled to the plenum 102. The plenum 102 provides pressurized cooled air to the server 104. The cooled air may be provided from a central source, such as a computer room air conditioner.
In block 304, the temperature sensors 108 distributed about the interior of the server 104 measure the temperatures of components and/or air within the server.
In block 306, based on the temperature measurements provided by the temperature sensors 108, the thermal controller 106 determines a level of cooling need to maintain each portion of the server 104, where the portions of the server are associated the distributed temperature sensors 108, within the predetermined operating temperature limits. For example, portions of the server 104 having a temperature above an upper operating temperature limit may require an increase in flow of cooled air, and portions of the server 104 having a temperature below a lower operating temperature limit may require a reduction in flow of cooled air.
In block 308, the thermal controller 106 positions the variable position flow restrictors (e.g., the louvers 112) within the server 104 to direct cooled air provided from the plenum 102 to the portions of the server 104 where cooling is needed. For example, the thermal controller 106 may adjust the positions of some of the flow restrictors 112 to increase the flow of cooled air to a portion of the server 104, and may adjust the positions of other of the flow restrictors 112 to decrease the flow of cooled air to a different portion of the server 104.
In block 402, the server 104 is operating. Components of the server 104 are dissipating heat, and cooling is provided to maintain the components of the server 104 within a predetermined operating temperature range. The inlets of the server 104 are coupled to the plenum 102. The plenum 102 provides pressurized cooled air to the server 104. The cooled air may be provided from a central source, such as a computer room air conditioner.
In block 404, the temperature sensors 108 distributed about the interior of the server 104 measure the temperatures of components and/or air within the server.
In block 406, based on the temperature measurements provided by the temperature sensors 108, the thermal controller 106 determines a level of cooling need to maintain each portion of the server 104 within the predetermined operating temperature limits. The thermal controller 106 determines the level of cooling needed by each portion of the server 104 based on temperature measurements provided by the temperature sensors 108 and/or based on other server operation information (e.g., clock rates, bus utilization, etc.) indicative of a level of cooling needed by a portion of the server 104.
In block 408, the thermal controller 106 generates control signals to adjust the cooling provided to portions of the server 104. Some implementations of the thermal controller 106 are fan controllers that generate PWM fan speed control signals. The thermal controller generates the control signals based on the determined cooling needs of each region or portion of the server 104.
In block 410, the positions of the flow restrictors 112 within the server 104 are set in accordance with the control signals generated by the thermal controller 106. The flow restrictors (e.g., the louvers 112) are set to direct cooled air provided from the plenum 102 to the portions of the server 104 where cooling is needed. For example, the thermal controller 106 may adjust the positions of some of the flow restrictors 112 to increase the flow of cooled air to a portion of the server 104, and may adjust the positions of other of the flow restrictors 112 to decrease the flow of cooled air to a different portion of the server 104. In some implementations, each flow restrictor 112 is opened in proportion to the duty cycle of the PWM control signal associated with the flow restrictor 112 (e.g., 100% duty cycle—fully open, 0% duty cycle—fully closed).
The above discussion is meant to be illustrative of the principles and various embodiments of the present invention. Numerous variations and modifications will become apparent to those skilled in the art once the above disclosure is fully appreciated. It is intended that the following claims be interpreted to embrace all such variations and modifications.
