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Optimal reduction of acoustic noise in a BladeCenter server system

IP.com Disclosure Number: IPCOM000033523D
Original Publication Date: 2004-Dec-14
Included in the Prior Art Database: 2004-Dec-14
Document File: 9 page(s) / 46K

Publishing Venue

IBM

Abstract

The present invention divides a system of server blades into air-flow domains and operates on each domain according to the optimal fan speed algorithm specified below. The algorithm automatically accounts for environmental variables such as humidity or elevation. Optimized fan speeds produce lower acoustic noise and reduced power requirements of the system. The optimal fan speed algorithm is a control loop that seeks to provide rapid cooling to the server blades when a temperature increase is sensed and drives to a stable, predetermined target temperature. The target temperature is defined by the manufacturer of the component such that the temperature may be maintained indefinitely without sustaining damage to the part. The control loop must provide stability in the sense that the fan speeds will come to steady state after a temperature step has been encountered in the air-flow domain. An improper implementation of the algorithm may result in fan speeds oscillating between minimum and maximum values.

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Optimal reduction of acoustic noise in a BladeCenter server system

    The latest packaging and process technologies have created dense electronic circuits and as a result, a large amount of heat is generated in products such as computer servers (See US Patent 2002/0015287). The general solution to this problem is to blow air across the surfaces of the components until the chips are sufficiently cooled. Unfortunately, the amount of air flow needed to cool dense arrays of components such as IBM BladeCenter server blades requires either a small number of large fans or a large number of small fans. In either case, a great deal of acoustic noise is generated and the already high power requirements of the system are increased as a result of the fans. It is desirable to minimize this noise to improve the working environment around the servers while at the same time maintaining efficient cooling of the electronic components. This has the additional benefit of reducing power requirements to run the system.

    The current solution to this problem is to read a temperature from a sensor within the system and run the fans at a proportional rate. As the server blades heat the domain the fan speed is altered accordingly. The problem with this system is that in a dense configuration a single blade can heat up causing the aggregated system fans to operate at disproportionately high levels, thereby increasing the amount of environmental noise. Also, operating conditions in which the server systems function may vary widely and the fan speeds which work correctly at one time or in one environment will not be correct for another. For example, in environments that are in particularly humid a particular fan speed will cool blades with a different efficiency than areas in particularly dry environments. The present invention includes an algorithm used in a partitioned chassis to determine the minimum fan speed possible in consideration of the current environmental conditions. The result is that the smallest number of fans operate at minimal speeds reducing both the acoustic noise and power requirements of the system.

    The present invention divides a system of server blades into air-flow domains and operates on each domain according to the optimal fan speed algorithm specified below. The algorithm automatically accounts for environmental variables such as humidity or elevation. Optimized fan speeds produce lower acoustic noise and reduced power requirements of the system.

     The optimal fan speed algorithm is a control loop that seeks to provide rapid cooling to the server blades when a temperature increase is sensed and drives to a stable, predetermined target temperature. The target temperature is defined by the manufacturer of the component such that the temperature may be maintained indefinitely without sustaining damage to the part. The control loop must provide stability in the sense that the fan speeds will come to steady state after a temperature step has be...