Abstract:
A quick start method for starting up a system easily and quickly is disclosed. A memory control unit reads the start-up data prestored in a storage unit, using auxiliary power supplied from an auxiliary power supply unit. Also, the memory control unit writes the read start-up data into RAM. As well, the memory control unit reads and outputs the start-up data written in RAM when the main power is turned on.

Description:
[0001]    This application is based upon and claims the benefit of priority from Japanese Patent Application No. 2006-275115 filed on Oct. 6, 2006, the content of which is incorporated by reference. 
       BACKGROUND OF THE INVENTION 
       [0002]    1. Field of the Invention 
         [0003]    The present invention relates to a storage device for use in starting up a system comprising a computer and its start-up method. 
         [0004]    2. Description of the Related Art 
         [0005]    Nowadays, a hard disk is mostly used as a storage device for storing an operating system or application program (hereinafter referred to as start-up data) for activating a system comprising a computer or an electronic computer. Particularly in the personal computers in recent years, an enormous amount of data is often processed, whereby there is a great demand for using high capacity hard disks. 
         [0006]    The start-up data stored in the hard disk is read from the hard disk when the system is started, and written into a memory such as a RAM (Random Access Memory) accessible by a CPU that is the control unit of the system. Thereby, the system can perform a predetermined process. 
         [0007]      FIG. 1  shows one example of the configuration around a storage unit in a typical system comprising memory control unit  1004 , storage unit  1007 , I/O control unit  1008 , CPU  1009 , RAM  1010  and BIOS_ROM  1011 . I/O control unit  1008 , CPU  1009 , RAM  1010  and BIOS_ROM  1011  are connected to bus  1012 . 
         [0008]    Storage unit  1007  is a mass storage device such as a hard disk that stores the start-up data for activating the system. Memory control unit  1004  controls the reading the start-up data stored in the storage unit  1007 . I/O control unit  1008  controls each I/O with an I/O instruction to be executed by CPU  1009 . RAM  1010  is a storage area for use when CPU  1009  runs a program that includes an operating system. BIOS_ROM  1011  is non-volatile memory that stores firmware for performing initialization and autonomous diagnosis of the hardware at the time to start the system. CPU  1009  is a processor for controlling them. 
         [0009]    When the power is turned on in the system having the above configuration, the start-up data stored in storage unit  1007  is read by memory control unit  1004 . And the system is started using the read start-up data. 
         [0010]    Also, one of the characteristics of a hard disk is that there is a certain probability that failure will occur due to the mechanical structure. Therefore, in a computer system such as a server requiring reliability, it is common that a redundant configuration such as dual hard disk is employed. 
         [0011]    In view of this background, recently, a system constituting a storage device using a non-volatile semiconductor storage element (hereinafter referred to as a non-volatile memory) represented by a flash memory was disclosed in JP-2003-345602A. Thereby, reliability can be improved by removing the mechanical unit s from the system. 
         [0012]    However, non-volatile memory has the drawbacks in which access speed is typically slower than that of a hard disk and the write number is restricted. 
         [0013]    In particular, the slower access speed has a direct influence on the system performance not only in starting the operation of loading or saving the program, but also when the storage device is used as virtual storage by the operating system. Also, there is the problem that slower access speed influences the start-up time of the device, such as system boot up, which needs to be as short as possible. 
         [0014]    Thus, there is disclosed in JP-2004-030184A a technique for increasing the speed of the start up operation by storing data, that is stored in the hard disk, in a memory that is connected to a high speed bus, and by reading data, that is stored in memory, when starting the system. 
         [0015]    However, in the technique as described in JP-2004-030184A, there is a problem that, when the data stored in the hard disk is transferred to memory that is connected to the high speed bus, the overall system has to be started up. 
       SUMMARY OF THE INVENTION 
       [0016]    An object of the present invention is to provide a storage device with which the system can be quickly and easily started, and also to provide a start up method. 
         [0017]    In this invention, the start-up data prestored in a non-volatile storage unit is read by a memory control unit, using an auxiliary power which is different from the main power that is used to start up the system. The read start-up data is written into start-up RAM. And when the main power is turned on, the start-up data that is written into the start-up RAM is read and output to the system by the memory control unit. 
         [0018]    Thereby, the time required for starting the system can be greatly shortened. 
         [0019]    The above and other objects, features, and advantages of the present invention will become apparent from the following description with reference to the accompanying drawings which illustrate an example of the present invention. 
     
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0020]      FIG. 1  is a diagram showing one example of the configuration of a storage unit in a typical system; 
           [0021]      FIG. 2  is a diagram showing one exemplary embodiment of a system to which a storage device of the invention is applied; and 
           [0022]      FIG. 3  is a flowchart for explaining a start-up method for the system in the form as shown in  FIG. 2 . 
       
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS 
       [0023]    Referring to  FIG. 2 , a system comprises power supply unit  101 , auxiliary power supply unit  102 , sub CPU  103 , memory control unit  104 , RAM bridge  105 , RAMs  106  and  1   10 , storage unit  107 , I/O control unit  108 , main CPU  109 , BIOS_ROM  111  and bus  112 . I/O control unit  108 , main CPU  109 , RAM  110  and BIOS_ROM  111  are connected to bus  112 . 
         [0024]    Power supply unit  101  is a device for converting AC power supplied from the outside to DC power supplied to the system or to a battery powered device. 
         [0025]    Auxiliary power supply unit  102  generates auxiliary power supply voltage, based on power supply voltage output from power supply unit  101 , and supplies the power to each component enclosed by the broken line in  FIG. 1 . 
         [0026]    The sub CPU  103  is a sub-processor that controls memory control unit  104  in a state where only the auxiliary power supply is turned on. Also, it is connected to memory control unit  104 , and outputs to memory control unit  104  instructions for copying the data stored in storage unit  107  that has slower access speed from storage unit  107  via RAM bridge  105  to RAM  106 . 
         [0027]    Memory control unit  104  controls a plurality of storage devices including RAM  106  and storage unit  107  connected lower it in accordance with an access instruction outputted from I/O control unit  108  or sub CPU  103 . In general, it is assumed that a control circuit such as an IDE (Integrated Device Electronics) is used. 
         [0028]    RAM bridge  105  converts a control signal such as a write signal or a read signal output from memory control unit  104  to a control signal for controlling RAM  106  connected lower RAM bridge  105 . RAM bridge  105  has a function of returning information that shows that the storage device can normally boot the system to memory control unit  104 . 
         [0029]    RAM  106  is RAM (Random Access Memory) that is a semiconductor memory. It is the start-up RAM, into which digital data including a boot image read from storage unit  107  is written by memory control unit  104 , and has a storage area for having the contents while the auxiliary power is applied. 
         [0030]    Storage unit  107  stores start-up data such as an operating system or an application program operating on it. Herein, it is a mass storage device such as a hard disk or a silicon disk device using a non-volatile storage element such as a flash memory. 
         [0031]    I/O control unit  108  controls each I/O with an I/O instruction executed by main CPU  109 . Herein, I/O control unit  108  takes charge of decoding an access instruction to the storage device, and issuing a control instruction to memory control unit  104 . Also, a power switch for turning on the main power is connected to I/O control unit  108 . 
         [0032]    RAM  110  is a storage area for use when main CPU  109  runs a program including the operating system after the main power is turned on. 
         [0033]    BIOS_ROM  111  is non-volatile memory that stores firmware for performing the initialization and autonomous diagnosis of hardware when starting the system. 
         [0034]    Main CPU  109  is a central processor for controlling each component as described above. 
         [0035]    The components using the auxiliary power include sub CPU  103 , memory control unit  104 , RAM bridge  105 , RAM  106 , and storage unit  107  among the components as shown in  FIG. 2 . Also, the components using the main power include I/O control unit  108 , main CPU  109 , RAM  110  and BIOS_ROM  111 . Also, a portion as indicated by the broken line in  FIG. 2  corresponds to the storage device of the invention. 
         [0036]    Referring to  FIG. 3 , a start-up method for the system with the configuration as shown in  FIG. 2  will be described below. 
         [0037]    When a power such as AC power is supplied to power supply unit  101  from the outside, auxiliary power supply output is determined in auxiliary power supply unit  102  at step  1 , whereby auxiliary power is supplied to sub CPU  103 , memory control unit  104 , RAM bridge  105 , RAM  106  and storage unit  107 . Herein, a secondary side power supply voltage that is the main power is not output from power supply unit  101  until the power switch connected to I/O control unit  108  is turned on. 
         [0038]    Then, sub CPU  103  to which the auxiliary power is supplied is started at step  2 . And an instruction for copying the operating system including the boot image and the application program running on it stored in storage unit  107  from storage unit  107  via RAM bridge  105  to RAM  106  is output from sub CPU  103  to memory control unit  104 . And the operating system including the boot image and the application program running on it are copied from storage unit  107  via RAM bridge  105  to RAM  106  by memory control unit  104  at step  3 . 
         [0039]    Thereafter, it is determined at step  4  whether the power switch connected to I/O control unit  108  is turned on. The power switch may be monitored at a preset period to check whether it is turned on. By changing the predetermined signal at the time that the power switch is turned on, it is possible to detect whether the power switch is turned on. This judgement will continue until the power switch is turned on. 
         [0040]    When it is judged that the power switch connected to I/O control unit  108  is turned on, a power-on signal is output from I/O control unit  108  to power supply unit  101 . This power-on signal, for which no particular signal format has been specified here, needs to be capable recognizing that the power has been turned on. And when the power-on signal is input into the power supply unit  101 , the secondary side power supply voltage that is the main power is output from power supply unit  101  to I/O control unit  108 , main CPU  109 , RAM  110 , and BIOS_ROM  111  at step  5 . 
         [0041]    When the secondary side power supply voltage is supplied to each component, main CPU  109  is activated at step  6 , whereby the initialization and autonomous diagnosis of the hardware is performed, using data stored in BIOS_ROM  111 . 
         [0042]    Thereafter, at step  7 , the operating system including the boot image and the application program running on it, which are stored in RAM  106 , are read by memory control unit  104 , and are output via I/O control unit  108  onto bus  112 , so that the image boot is executed as the system. 
         [0043]    Thereby, the time required for system start-up can be greatly shortened as compared with booting up from storage unit  107  that has typically slower access speed. 
         [0044]    Herein, the time required for copying the operating system including the boot image and the application program running on it from storage unit  107  into RAM  106  may be very long. In this case, this problem can be avoided if the data copied from storage unit  107  to RAM  106  is limited to the minimum data needed for the system boot and if the remaining data is copied when or after the system is started. Or a method for outputting no secondary side power supply voltage after the completion of copying may be employed. 
         [0045]    And the system becomes operable at step  8 . While the operating system and the application program are operating, in general, access to the storage device occurs frequently. For example, the program load and save operations and access to virtual memory by the operating system are performed. In this invention, RAM 16  is the storage device that is recognized by the system, and the operating system and application program must access RAM 106  which has the same high speed access as a normal storage device. Thereby, it is unnecessary to consider improvement of the access speed, or limitation of the write number that is a problem which arises when a semiconductor storage element such as flash memory is employed as the storage device. 
         [0046]    Thereafter, when the system is shut down at step  9 , the secondary side power supply voltage output that is the main power is turned OFF at step  10 , but the state of RAM  106  is maintained by the auxiliary power to enable a fast system boot to be made when the main power is turned on the next time. 
         [0047]    In the typical operation, once the primary side power supply voltage of power supply unit  101  is turned on, the power switch or the system controls a power-on signal, and regulates only the secondary side power supply voltage to turn on or off the system power. That is, auxiliary power supply unit  102  continues to operate as long as the primary side power supply voltage is turned on, and the contents stored in RAM  106  are maintained using auxiliary power that is output from auxiliary power supply unit  102  Thereby, when the power switch is turned on the next time, a fast system boot is enabled without again implementing the copying process from storage unit  107  to RAM  106 , which was previously implemented. 
         [0048]    Also, in a typical operating system in which the typical storage device is used as virtual storage, to reduce the probability of causing disk swap, the main memory capacity is increased for the purpose of improving system performance. However, in the present invention, RAM having high access speed is used as the storage device. Thereby, even when the storage device is used as virtual storage, performance degradation can be minimized. Therefore, even when a number of disk swaps occur due to a multitasking operation, performance degradation can be minimized. 
         [0049]    Though RAM bridge  105  is connected to memory control unit  104  in  FIG. 2 , another pair of RAM bridge and RAM may be connected to memory control unit  104 . In this configuration, the contents stored in each RAM unit can be mirrored mutually to improve reliability. 
         [0050]    While an exemplary embodiment of the present invention has been described in specific terms, such description is for illustrative purpose only, and it is to be understood that changes and variations may be made without departing from the spirit or scope of the following claims.