Abstract:
A control device includes a control unit having operating modes having different heating values, and a fan unit including at least one fan for cooling the control unit in which the number of rotations varies depending on a voltage. The control unit includes a voltage supplying section for supplying different voltages corresponding to the operating modes. The fan unit includes a rotation control unit for rotating the fan with the highest voltage among the supplied different voltages.

Description:
BACKGROUND OF THE INVENTION  
       [0001]     1. Field of the Invention  
         [0002]     The present invention relates to a control device including a cooling fan unit.  
         [0003]     2. Description of the Related Art  
         [0004]     In recent years, as various types of data have become digitized and handled on computers, the importance of storage servers that can efficiently store large amounts of data, separately from the computers, has been increasing. The storage servers have a feature in that, by employing RAID (redundant array of independent disks) technology, their reliability becomes more enhanced than simple disk drives. In addition, in general, the storage servers include built-in caches. This makes it possible to shorten a time to access data.  
         [0005]     In the RAID technology, reliability is enhanced by techniques such as RAID-1 in which the same data is stored on a plurality of disks, and RAID-5 in which parity information is stored on disks in distributed form.  
         [0006]     A storage server includes a control device and a disk drive.  
         [0007]     The control device includes a main control unit, a control-and-monitoring unit, a power supply unit, a fan unit, and a breaker.  
         [0008]     The main control unit includes a central processing unit (CPU), a memory controller, a host adapter, a cache memory, and a disk adapter. In order to realize various functions and to require having high performance, the main control unit consumes a large amount of power of approximately several hundred watts, and generates a very large heating value.  
         [0009]     The control-and-monitoring unit has a function of monitoring power, temperature, etc., and includes a microcomputer, a memory, and a monitoring circuit that have minimum performance. Accordingly, the control-and-monitoring unit only needs power of approximately several watts, thus generating a small heating value.  
         [0010]     The power supply unit uses standby power to drive the control-and-monitoring unit, and uses main power to drive the main control unit.  
         [0011]     During the use of the standby power, the fan unit is not driven. During the use of the main power, the fan unit cools the main control unit and the control-and-monitoring unit.  
         [0012]     The power supply unit and the fan unit may be used in common to a plurality of control devices without being provided in units of control devices.  
         [0013]     Power supply control by the control device is described below.  
         [0014]     At first, by turning on the breaker, the control-and-monitoring unit is started to operate. After that, by pressing a power supply switch of the control-and-monitoring unit, the control-and-monitoring unit supplies power to the main control unit.  
         [0015]     Cooling of the control-and-monitoring unit and the main control unit by the fan unit is performed after the main control unit is activated, and is not performed in a standby mode in which only the control-and-monitoring unit is driven.  
         [0016]     In addition, with increased demand for an increase in device size, and device reliability and usability, the control-and-monitoring unit also tends to be highly functional and of high performance. For example, a large storage server may include several hundred or more disk drives. Accordingly, the load on the control-and-monitoring unit for monitoring the states of the disk drives increases.  
         [0017]     As described above, as the control-and-monitoring unit becomes highly functional and comes to have high performance, power consumption accordingly increases, so that generated heat also increases. Therefore, during the standby mode in which only the control-and-monitoring unit is driven, relying on natural cooling, as it has been performed, is difficult.  
       SUMMARY OF THE INVENTION  
       [0018]     According to an aspect of the present invention, a control device includes a control unit having a plurality of operating modes having different heating values, and a fan unit including at least one fan for cooling the control unit in which the number of rotations varies depending on a voltage. The control unit includes a voltage supplying section for supplying the fan unit with different voltages corresponding to the operating modes, and the fan unit includes a rotation control section for rotating the at least one fan with the highest voltage among the supplied different voltages.  
         [0019]     In each operating mode of the control device, fan rotation can be performed at the optimal number of rotations for cooling. Thus, heating by the control device can optimally be suppressed. 
     
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       [0020]      FIG. 1  is a block diagram of a control device according to an embodiment of the present invention;  
         [0021]      FIG. 2  is an illustration of a power-on/off sequence in the embodiment; and  
         [0022]      FIG. 3  is a circuit block diagram of a fan unit board in the embodiment.  
     
    
     DESCRIPTION OF THE PREFERRED EMBODIMENTS  
       [0023]      FIG. 1  is a block diagram of a control device  1  according to an embodiment of the present invention.  
         [0024]      FIG. 1  shows the configuration of the control device  1  in terms of a power system.  
         [0025]     The control device  1  includes a control unit  2 , a braker  3 , a power supply unit  4 , and a fan unit  5 .  
         [0026]     The control unit  2  includes a standby control section  31  and a main control section  32 .  
         [0027]     The breaker  3  determines whether to input external power of AC 100 or 200 volts to the power supply unit  4 . The power supply unit  4  generates 12-volt DC power from the external power of AC 100 or 200 volts. The generated 12-volt DC power is supplied to DC-DC converters (hereinafter referred to as “DDCs” )  11  and FET  13  of the standby control section  31 .  
         [0028]     The fan unit  5  cools the entirety of the control unit  2 .  
         [0029]     The standby control section  31  includes the DDCs  11 , a control-and-monitoring section  12 , and the FET  13 . One DDC  11  converts the 12-volt power supplied from the power supply unit  4  to 5-volt power for the fan unit  5 , and the other DDC  11  converts the 12-volt power to a predetermined voltage that is supplied as power to the control-and-monitoring section  12 .  
         [0030]     The control-and-monitoring section  12  controls initial setting of a CPU  22 , a memory controller  23 , a host adapter  25 , and a disk adapter  26 , monitoring of power and temperature, etc. The control-and-monitoring section  12  also includes power-on and power-off switches.  
         [0031]     In response to a power-on or power-off instruction from the control-and-monitoring section  12 , the FET  13  controls starting or stopping supply of the 12-volt power supplied by the power supply unit  4  to the fan unit  5  and the main control section  32 .  
         [0032]     The main control section  32  includes DDCs  21 , the CPU  22 , a memory controller  23 , a cache memory  24 , a host adapter  25 , and a disk adapter  26 .  
         [0033]     After converting the 12-volt power to the voltages required by corresponding units, such as the CPU  22 , and the DDCs  21  supply the required voltages to the corresponding units.  
         [0034]     The CPU  22  realizes basic functions of the control device  1 , such as control of the host adapter  25  and the disk adapter  26 , RAID control, and cache control.  
         [0035]     The memory controller  23  mutually connects the CPU  22 , the host adapter  25 , the disk adapter  26 , and the cache memory  24 , and realizes exchanging data and messages among them.  
         [0036]     The cache memory  24  temporarily stores data that is transmitted to and received from a host or a disk drive.  
         [0037]     The host adapter  25  controls data transmission and reception to/from the host.  
         [0038]     The disk adapter  26  controls data transmission and reception to/from the disk drive.  
         [0039]     Next, a power supply operation of the control device  1  is described below.  
         [0040]     AC power input to the control device  1  is converted into DC power by the power supply unit  4 . In general, a voltage of 100 or 200 volts is used as the AC power, and a voltage of 12 volts is used as the DC power.  
         [0041]     The DC power supplied from the power supply unit  4  is divided on a printed-circuit board forming the control unit  2  into three, that is, power supplied to the control-and-monitoring section  12 , power supplied to the fan unit  5 , and power supplied to the main control section  32 .  
         [0042]     Specifically, the 5-volt power obtained by one DDC  11  is supplied to the fan unit  5 .  
         [0043]     Also, the power required by the control-and-monitoring section  12  is converted and supplied by the DDCs  11 .  
         [0044]     In addition, supply of the 12-volt power for the fan unit  5  and the main control section  32  is started and stopped by the FET  13 . Control of the FET  13  is handled by the control-and-monitoring section  12 .  
         [0045]     The 12-volt power supplied to the main control section  32  is converted by the DDCs  21  to the voltages required by various electronic components on the printed-circuit board.  
         [0046]      FIG. 2  shows the following power-on/power-off sequence in the embodiment. 
    (1) By plugging the control device  1  in and turning on the breaker  3 , the AC power is supplied to the power supply unit  4 .     (2) The power supply unit  4  outputs the 12-volt DC power after converting the AC power, and the 12-volt DC power is converted by one DDC  11  to a 5-volt voltage or the like before being supplied to the control-and-monitoring section  12 . Thus, the control-and-monitoring section  12  is activated and started to operate. In addition, since the 5-volt power output from the other DDC  11  is supplied also to the fan unit  5 , fan rotation of the fan unit  5  starts at low speed with a low voltage. At this time, the control-and-monitoring section  12  closes a switch formed by the FET  13 , so that the main control section  32  is supplied with no power. Control unit  2  is in a stand-by mode.     (3) In response to pressing of the power-on switch, the switch formed by the FET  13  is opened by the control-and-monitoring section  12  to start supply of power to the main control section  32  and the fan unit  5 . Then, the main control section  32  is activated and started to operate. In addition, by supplying the 12-volt power, the fan unit  5  is started to have fan rotation at high speed. Control unit  2  is in a normal mode.     (4) In response to pressing of the power-off switch, the control-and-monitoring section  12  closes the switch formed by the FET  13 , so that the supply of the power to the main control section  32  and the fan unit  5  is stopped. Then, the main control section  32  is stopped to operate. The fan unit  5  changes to have fan rotation at low speed since fan unit  5  continues to be supplied with the 5-volt power. Control unit  2  is in the stand-by mode.     (5) By turning off the breaker  3 , the input of the AC power to the power supply unit  4  is stopped, so that the output of the 12-volt DC power is also stopped, the control-and-monitoring section  12  is also stopped to operate, and the fan rotation is stopped.      
         [0052]      FIG. 3  is a circuit block diagram of a fan unit board  51  in the embodiment.  
         [0053]     The fan unit  5  includes a plurality of fans and the fan unit board  51 .  
         [0054]     Two voltages of 12 volts and 5 volts are applied to the fan unit  5 . Both voltages are supplied from a connector CN 1  of the fan unit board  51  in the fan unit  5  to the anodes of two diodes  41  through inrush prevention circuits  42 . The cathodes of the diodes  41  are wired in an OR manner. The output of wired OR connection is supplied from a connector CN 2  of the fan unit board  51  to FAN# 1 .  
         [0055]     As a result, although the voltages of 12 volts and 5 volts are supplied to the fan unit  5  while the main control section  32  is operating, the voltage of 12 volts is output because of the wired OR connection, and FAN# 1  rotates at high speed. Since only the voltage of 12 volts is supplied from a connector CN 3  of the fan unit board  51  to FAN# 2 , FAN# 2  rotates at high speed.  
         [0056]     In addition, in a standby mode in which only the control-and-monitoring section  12  is driven, only the voltage of 5 volts is supplied to the fan unit  5 . Thus, the output of the wired OR connection is 5 volts. This causes FAN# 1  to rotate at low speed. The wired OR connection is used only for FAN#l as a single fan. Accordingly, FAN# 2  as another fan does not rotate since it is not supplied with the voltage of 12 volts.  
         [0057]     As a result, in the standby mode, among the plurality of fans, only FAN# 1  is supplied with power, and the other fans are not supplied with power.  
         [0058]     This enables the fan unit  5  to be driven with minimum noise and power consumption that are necessary for cooling the control-and-monitoring section  12 .