Abstract:
A rack system for mounting at least one data processing unit includes a shelf operable for moving from a position internally of the rack system to a position externally of the rack system. The shelf has an aperture and a fluid mover for moving fluid through the aperture in the shelf when the shelf is located in its external position.

Description:
TECHNICAL FIELD 
       [0001]    The present invention relates to the field of data center cooling. More particularly, it relates to the enhancement of cooling air flow to the machines in a data center. 
       RELATED ART 
       [0002]    The growth of computer networking, and particularly the rapid growth of the use of the Internet, has resulted in a rapid increase in demand for server computers. Most commonly, a number of modular server units, for example the modular computing units known as “blade” servers, are removably mounted in equipment racks. Typically a large number of such racks are housed in a building known as a data center. In a data center, one or more large rooms are provided. Each room houses rows of equipment racks and their mounted servers, and associated cabling and network communication equipment. 
         [0003]    A modern rack when fully loaded with blade servers consumes a large amount of electrical power when operating. In consequence, a large amount of waste heat is produced. Many data centers now employ individual racks of blade servers in which each rack develops 20 kW or more of waste heat. To avoid damage to the servers by overheating, this waste heat must be removed. 
         [0004]    In a commonly used arrangement, data center rooms are cooled by computer room air conditioning units (termed CRACs) which circulate cooled air which passes through the rack units for heat removal. Typically, a data center room comprises a raised floor above a plenum chamber through which cooled air is blown by CRAC units. Rows of server racks are mounted on the floor separated by aisles. Networks of grilles in the floors of the aisles between rows of server racks allow cooled air from the plenum to rise into the aisles. From here it is typically drawn through the front of the racks by fans mounted in the racks. Heated air passes out of the other side of the rack and is drawn up into a roof plenum chamber for removal or recirculation through the CRAC units. In a commonly used arrangement, an aisle comprises two rows of server racks whose fronts face each other with the floor of the aisle space between the two rows of server racks comprising a number of grilles through which cooled air rises. This is termed a cold aisle. Behind each row of racks is a hot aisle to which heated air passes after flowing through the racks and then rises for removal by way of the roof plenum chamber. 
         [0005]    Maintaining the free flow of cooling air is vital for maintaining the temperatures of all the blade servers within acceptable operational limits. However, there are times when the introduction of obstructions into aisles is unavoidable. For example, it is sometimes necessary to provide a shelf for the support of a keyboard and display of a server unit installed for the purpose of performing hardware management operations on the other installed servers. This is known as a hardware management console or HMC. The shelf is typically installed in a horizontal rack slot at a height convenient for use by a maintenance operator. The shelf runs on rails so that it may be pulled out from the front of the rack to form a horizontal management operations shelf. It includes a horizontal keyboard and behind this a flat screen display. The display is horizontal when in a stored position in the rack but moveable to a near vertical position to provide a display interface to the HMC when the shelf is withdrawn from the rack into an operating position. 
         [0006]    During operation of the HMC, the shelf extending from the rack front forms a barrier to vertically rising cooling air in the cold aisle. The supply of cooling air is an energy intensive operation. It is therefore desirable to optimize the supply of cooling air to provide just enough to maintain efficient server operation at every position in the rack. Any obstruction of flow by a shelf will restrict the supply of cooling air supply to blade servers in the rack above the shelf. This is likely therefore to result in the overheating of these blade servers. It would be desirable to provide a solution to the problem of restricted air flow resulting from the use of a shelf protruding from the front of a rack, such as when using a HMC. 
         [0007]    U.S. Pat. No. 6,801,428 discloses an arrangement for cooling a series of closely spaced upright computer components mounted to a support, the arrangement including a tray having a plurality of air moving devices such as fans. Members are used for helping removably mount the tray to the support in a generally horizontal disposition, and the air moving devices move air in a generally upright path of travel to help cool the upright computer components. The tray also has a series of connector ports for connecting electrically to outputs from individual ones of the computer components. 
       SUMMARY OF THE INVENTION 
       [0008]    Viewed from a first aspect, the invention provides a rack system for mounting at least one data processing unit, the rack system comprising a shelf operable for moving from a position internally of the rack system to a position externally of the rack system. The shelf comprises an aperture in the shelf and a fluid mover for moving fluid through the aperture in the shelf when the shelf is located in its external position. 
         [0009]    In an embodiment of the rack system, the fluid mover is an air mover. 
         [0010]    In an embodiment of the rack system, the shelf is mounted on rails operable for moving the shelf from the position internally of the rack system to the position externally of the rack system. 
         [0011]    In an embodiment of the rack system, the air mover is operable for moving air from below the shelf. 
         [0012]    In an embodiment of the rack system, the air mover comprises at least one fan. 
         [0013]    In an embodiment of the rack system, the external position is an operating position of the shelf. 
         [0014]    In an embodiment of the rack system, the shelf comprises a hardware management console. 
         [0015]    Viewed from a second aspect, the invention provides a shelf for mounting in a rack system, the rack system for mounting at least one data processing unit, the shelf being operable for moving from a position internally of the rack system to a position externally of the rack system. The shelf comprises an aperture in the shelf and a fluid mover for moving fluid through the aperture in the shelf when the shelf is located in its external position. 
         [0016]    In an embodiment of the shelf, the fluid mover is an air mover. 
         [0017]    In an embodiment of the shelf, the shelf is mounted on rails operable for moving the shelf from the position internally of the rack system to the position externally of the rack system. 
         [0018]    In an embodiment of the shelf, the air mover is operable for moving air from below the shelf. 
         [0019]    In an embodiment of the shelf, the air mover comprises at least one fan. 
         [0020]    In an embodiment of the shelf, the external position is an operating position of the shelf. 
         [0021]    In an embodiment of the shelf, the shelf comprises a hardware management console. 
         [0022]    Viewed from a third aspect, the invention provides a method for supplying cooling fluid to a rack system, the rack system for mounting at least one data processing unit, the method comprising providing a shelf operable for moving from a position internally of the rack system to a position externally of the rack system. The shelf comprises an aperture in the shelf and a fluid mover for moving fluid through the aperture in the shelf when the shelf is located in its external position. 
         [0023]    In an embodiment of the method, the fluid mover is an air mover. 
         [0024]    In an embodiment of the method, the shelf is mounted on rails operable for moving the shelf from the position internally of the rack system to the position externally of the rack system. 
         [0025]    In an embodiment of the method, the air mover is operable for moving air from below the shelf. 
         [0026]    In an embodiment of the method, the air mover comprises at least one fan. 
         [0027]    In an embodiment of the method, the external position is an operating position of the shelf. 
         [0028]    In an embodiment of the method, the shelf comprises a hardware management console. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0029]    Embodiments of the invention will now be described in detail by way of example only with reference to the following drawings. 
           [0030]      FIG. 1  is a cross-section of a prior art data center in which embodiments of the invention may be employed. 
           [0031]      FIG. 2  is a cross-section of an equipment rack as illustrated in the data center of  FIG. 1  in which embodiments of the invention may be employed. 
           [0032]      FIGS. 3   a ,  3   b  and  3   c  are perspective views illustrating the deployment of a hardware management console shelf according to the prior art. 
           [0033]      FIG. 4  is a cross section of a rack with a prior art hardware management console shelf deployed in its operational state. 
           [0034]      FIG. 5  is a perspective view illustrating an embodiment of the present invention. 
           [0035]      FIG. 6  is a cross-section of an equipment rack illustrating an embodiment of the present invention. 
       
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
       [0036]      FIG. 1  illustrates a cross-section of a data center room  100  suitable for incorporating embodiments of the present invention. A conditioning unit, for example a computer room air conditioning unit (CRAC)  110 , comprises chiller and blower components for, respectively, chilling and impelling fluid for circulating in the data center room. The circulating fluid functions for removal of heat generated by equipment operating in data center room  100 . In an embodiment, the circulating fluid is a gaseous fluid, for example the fluid is the ambient air of data center room  100 . In an embodiment, the CRAC  110  blows chilled air through a grille  115   a  into a sub-floor plenum chamber  120 . The sub-floor plenum chamber  120  extends over substantially the whole floor area of data center room  100 . The floor  122  is suitably supported above the sub-floor plenum chamber  120  to carry rows of equipment racks such as equipment racks  140   a  and  140   b  as illustrated. The equipment racks  140   a,    140   b  each comprise a rack framework suitable for mounting modular data processing units, for example server computing units such as blade servers. 
         [0037]    Air flows through the sub-floor plenum chamber  120  as shown by arrow  125 . Air flows from the sub-floor plenum chamber  120  up through grilles  115   b,    115   c  into a cold aisle  150   a.  From here air is drawn through the front of the racks  140   a,    140   b  by air movers, such as fans, mounted within the racks  140   a,    140   b.  The air flow  145   a,    145   b  is shown entering the front of the rack  140   a  and the air flow  145   c,    145   d  entering the front of the rack  140   b.  Air exits  155   a,    155   b  from the rear of the rack  140   a  into a hot aisle  150   b.  Similarly, air exits  155   c,    155   d  from the rear of the rack  140   b  into a hot aisle  150   c.  Air is then drawn upwards from the hot aisle  150   b  through a grille  115   d  in the roof  132  into a roof plenum chamber  130 . Similarly, air is drawn upwards from the hot aisle  150   c  through a grille  115   e  in the roof  132  into the roof plenum chamber  130 . The roof plenum chamber  130  extends over substantially the whole roof area of the data center room  100 . Air flows  135  through the roof plenum chamber  130  and re-enters the CRAC  110  by way of a grille  115   f.    
         [0038]      FIG. 2  illustrates an enlarged cross-section of the rack  140   a  of  FIG. 1 . Air is shown rising through the grille  115   c  from the sub-floor plenum chamber  120 . Air enters  145   a,    145   b  the front of the rack  140   a,  drawn by air movers, such as fans, mounted within the rack  140   a.  Air exits  155   a,    155   b  from the rear of the rack  140   a.  A typical arrangement of the rack  140   a  is shown in which the rack  140   a  is loaded with a plurality of substantially identical blade server units. The rack  140  is divided into vertical sections  210   a  to  210   f.  Each vertical section  210   a  to  210   f  comprises a plurality of vertically oriented blade servers each inserted on guide rails from front to back of the sections  210   a  to  210   f.  It will be understood that this is by way of example only. It will be understood that other arrangements are possible, for example using horizontally mounted data processing units mounted in the rack  140   a,  or a mix of horizontally and vertically mounted data processing units. 
         [0039]    Also shown is a shelf unit  220  within the rack  140   a.  The shelf unit  220  comprises a substantially flat horizontal unit, typically extending across substantially the whole of the width of the rack  140   a.  The shelf unit  220  is mounted on rails attached to the framework of the rack  140   a  and is operable for withdrawing from the front of the rack  140   a  to provide a working surface for use by a human operator. The shelf unit  220  will therefore be mounted in the rack  140   a,  for example at a height suitable for allowing comfortable use by a human operator, for example in a standing position. 
         [0040]      FIGS. 3   a  to  3   c  illustrate the deployment to an operating position of the shelf  220  suitable for incorporating embodiments of the present invention. In  FIGS. 3   a  to  3   c , the shelf unit  220  comprises a hardware management console, or HMC, which is an interface to a server unit installed for the purpose of allowing a human operator to perform hardware management operations on the other installed servers. In  FIG. 3   a , the shelf unit  220  runs on rails  330  in the rack  140   a  and is pulled out in direction  340   a  from the front  310  of the rack  140   a.    FIG. 3   b  shows the shelf unit  220  fully extended. The HMC has a keyboard  350  and a flat screen display  360 . The screen  360  lies flat in a non-operational position as shown in  FIG. 3   b  when the shelf  220  is extracted from the front  310  of the rack  140   a.  The screen  360  is raised to an operational position as shown by arrow  340   b.    FIG. 3   c  shows the shelf unit  220  with the HMC in an operational position. The shelf unit  220  provides a barrier to rising cool air  370   a.    
         [0041]      FIG. 4  illustrates a cross-section of the rack  140   a  of  FIG. 2 , but comprising the shelf unit  220  in an operating position fully extended from the rack  140   a.  The shelf unit  220  comprises an HMC comprising the keyboard  350  and the display  360 . Air  145   a  rises after passing through the grille  115   c  from the sub-floor plenum chamber  120 . Air  145   a  enters the front of the rack  140   a  sections  210   d  to  210   f  and exits from the rear of the rack  140   a  from sections  210   d  to  210   f.  The shelf  220  presents a barrier to the rising cool air  145   x.  Consequently, the cool air flow  145   y  which may enter the front of the rack  140   a  at sections  210   a  to  210   c  is much reduced. Servers in the rack  140   a  sections  210   a  to  210   c  are therefore at risk of overheating. 
         [0042]      FIG. 5  illustrates a shelf unit  520  extracted from the front  510  of a rack  540   a  according to an embodiment of the present invention. The shelf unit  520  comprises an HMC comprising a keyboard  550  and a display  560 . The shelf unit  520  further comprises an aperture comprising a fluid mover. In an embodiment, the fluid mover comprises an air mover for moving air  570   a  from below the shelf unit  520  through the aperture in the shelf unit  520  and exiting  570   b  above the shelf unit  520 . In the embodiment illustrated in  FIG. 5 , the air mover comprises fans  580   a  to  580   d  mounted within suitably shaped apertures in the shelf unit  520 . The fans  580   a  to  580   d  may, for example, be mounted within the apertures in the shelf  520  and not protrude substantially from upper or lower surfaces of the shelf  520 . The axes of rotation of the fan blades of the fans  580   a  to  580   d  may be orientated substantially vertically in relation to the rack  540   a.    
         [0043]      FIG. 6  illustrates a cross-section of the rack  540   a  comprising an embodiment of the present invention. The shelf  520  is shown extended in an operating position. The shelf  520  comprises an HMC comprising a keyboard  550  and a display  560 . The shelf  520  comprises an aperture comprising a fluid mover, for example, an air mover. In the illustrated embodiment, the air mover comprises fans,  580   a  and  580   b  illustrated in cross-section. Air  645   a  rises through a grille  615   c  from a sub-floor plenum chamber  620  and enters the front of rack  540   a.  Air  645   a  passes over servers mounted in sections  610   d  to  610   f  of the rack  540   a  and exits  655   a  from the rear of the rack  540   a.  Air  645   b  is moved through the shelf  520  by the air mover, comprising fans  580   a  and  580   b  shown. Air  645   b  enters the front of the rack  540   a  and passes over servers mounted in sections  610   a  to  610   c  and exits  655   b  from the rear of the rack  540   a.  The shelf  520  therefore presents a reduced barrier to rising cooling air and servers in sections  610   a  to  610   c  receive an enhanced supply of cooling air so that the risk of overheating is reduced. 
         [0044]    In a further embodiment with reference to  FIG. 2 , the shelf  220  comprises a simple shelf unit comprising an air mover in accordance with the present invention and does not comprise a HMC. In this embodiment it is possible to use the shelf unit to enhance the flow of cooling air. 
         [0045]    It will be apparent that although embodiments of the invention have been described in relation to a data center comprising racks comprising a plurality of blade server computing units, other arrangements are possible without departing from the invention. In further embodiments of the invention, other types of data processing units are employed. In one exemplary embodiment, data processing units comprise horizontally mounted modular units. In another exemplary embodiment, the rack comprises a small number of larger data processing units. In a further embodiment, data processing units comprise data storage units such as magnetic or optical disk data storage units.