Patent Publication Number: US-7590838-B2

Title: Remote boot method and mechanism, and computer-readable storage medium

Description:
BACKGROUND OF THE INVENTION 
     1. Field of the Invention 
     The present invention generally relates to remote boot methods and mechanisms and computer-readable storage media, and more particularly to a remote boot method and mechanism for carrying out a so-called boot process in a computer system to load an image of an operating system from a file apparatus that is connected to the computer system to a main memory of the computer system and to start the operating system, and to a computer-readable storage medium which stores a program for causing a computer to carry out such a boot process. 
     2. Description of the Related Art 
     In the computer system, the boot process which loads the image of the operating system from the file apparatus to the main memory and starts the operating system, is controlled by a boot firmware of the computer system. 
       FIG. 1  is a diagram showing an important part of a conventional computer system. In  FIG. 1 , a computer system  1  includes a main body part  11  and a system monitoring mechanism  12  that monitors the entire computer system  1 . A plurality of Hard Disk Drives (HDDs)  2 - 1 ,  2 - 2 ,  2 - 3 , . . . , a CDROM or DVDROM (CDROM/DVDROM) drive  3 , and a network apparatus  4  are connected to the computer system  1 , as file apparatuses. The main body part  11  includes a ROM firmware  21 , a Read Only Memory (ROM) or Flash Memory (FMEM)  22 , a Non-Volatile RAM (NVRAM)  23  and a main memory  24 . In addition, the main memory  24  includes a boot firmware  241 , an Operating System (OS) loader program (hereinafter simply referred to as an OS loader)  242  and an OS  243 . 
     The ROM firmware  21  is written in a ROM or FMEM, and this ROM firmware  21  is started when the power of the computer system  1  is turned ON, to thereby execute a hardware analysis and initializing processes within the computer system  1 . Thereafter, an image of the boot firmware that is compressed and stored in the ROM or FMEM  22  within the computer system  1  is located into the main memory  24 , and the control is transferred to the boot firmware  241 . The boot firmware  241  includes a driver program (hereinafter simply referred to as a driver) for controlling boot target apparatuses (file apparatuses) that are supported by the computer system  1 , and executes the boot process by selecting the target apparatus that is to be actually booted, from the boot target apparatuses that are connected to the computer system  1 , depending on preset boot information. Normally, the boot firmware  241  boots the OS loader  242  for booting the target OS  243 . The boot firmware  241  does not need to be able to analyze the file system of the OS  243 . Since the OS loader  242  that corresponds to the OS  243  can analyze the file system of the OS  243 , the boot firmware  241  can recognize the location of the OS loader  242  in the boot target apparatus, and if this OS loader  242  can be booted, the OS  243  can thereafter be booted by this OS loader  242 . In the computer system  1  shown in  FIG. 1 , the boot information is stored in the NVRAM  23 . The boot target apparatus that is to be automatically booted when starting the computer system  1  is determined from the plurality of boot target apparatuses that are connected to the computer system  1 , depending on the boot information that is stored in the NVRAM  23 . The boot information that is stored in the NVRAM  23  includes a BootXXXX variable and a BootOrder variable, where “XXXX” denotes a hexadecimal number from “0000” to “FFFF”. The BootXXXX variable includes device path information indicating a location where the boot target apparatus is connected to the computer system  1 , and information related to a file position and a file name of the OS loader  242 . The BootOrder variable specifies an order in which the boot target apparatuses indicated by the plurality of BootXXXX variables are to be booted. When the control is transferred to the boot firmware  241 , the boot firmware  241  initializes various drivers for booting and carries out a probing process with respect to the HDDs  2 - 1 ,  2 - 2 ,  2 - 3 , . . . that are connected to the computer system  1 . Thereafter, the value of the portion “XXXX” of the BootXXXX variable is specified from the BootOrder variable of the NVRAM variables, and the boot target apparatus specified by the BootXXXX variable and the OS loader  242  are booted. 
     Accordingly, the following functions f 1 ) through f 3 ) are realized by the boot firmware  241 .
         f 1 ) A function of using drivers thereof for controlling the boot target apparatuses such as the HDDs  2 - 1 ,  2 - 2 ,  2 - 3 , . . . , the CDROM/DVDROM drive  3  and the network apparatus  4 , and booting the OS loaders  242  stored in the boot target apparatuses;   f 2 ) A function of storing the boot information, such as the device path information of the boot target apparatus and information of the image of the target OS, in the NVRAM  23 ; and   f 3 ) A function of reading the boot information stored in the NVRAM  23 , and selecting the boot target apparatus based on a boot priority order.       

     According to the functions f 1 ) through f 3 ) described above, the boot process of the OS  243  by the boot firmware  241  may be regarded as functions to determine the boot target apparatus based on the boot information that is preset in the NVRAM  23  and to boot the OS loader  242 . But in addition, the boot process of the OS  243  by the boot firmware  241  includes a so-called remote boot function which temporarily executes a boot process from a boot apparatus different from the boot information that is preset in the NVRAM  23 , only for the next boot process, based on information received from the system monitoring mechanism  12 . 
       FIG. 2  is a diagram for explaining a path with which the boot firmware  241  acquires the boot information. In the normal boot process, the boot information is acquired from the NVRAM  23  that is managed by the boot firmware  241 . In case where the boot information also exists in the system monitoring mechanism  12 , the boot target apparatus is determined depending on the boot information from the system monitoring mechanism  12 , regardless of the boot information from the NVRAM  23 . The boot information in the system monitoring mechanism  12  may be specified by an application program  244  that is under the control of the OS operated in the computer system  1  or, specified by an external computer system  31  that is connected to the system monitoring mechanism  12  via a network  30 . 
     For example, a Japanese Laid-Open Patent Application No. 5-35489 proposes a method of loading an initial program in a computer work station that is connected to a LAN or the like, by determining a generation source of an initial program load control logic. In addition, a Japanese Laid-Open Patent Application No. 6-259351 proposes a method of automatically starting an auxiliary system when a failure is generated in an information processing apparatus. 
     In the computer system  1  described above, it is possible to specify a temporary boot from the application program  244  or the external computer  31 , by a remote boot control via the system monitoring mechanism  12 , regardless of the boot information set in the NVRAM  23  that is managed by the boot firmware  241 . However, although the boot firmware  241  can flexibly set the boot information depending on the system structure by setting detailed boot information in the NVRAM  23 , there was a problem in that the booting can only be specified from particular HDDs, CDROM/DVDROM drives and network apparatuses because a reference cannot be made to the information that is flexibly set in the NVRAM  23  when specifying the boot target apparatus via the system monitoring mechanism  12 . In other words, when storing the boot information in the NVRAM  23 , even an apparatus that is connected via an interface that is not provided as an on-board interface of the target computer system  1  may be freely set since the device path information of the boot target apparatus can be freely set as the boot information, and the boot path may be defined flexibly depending on the system structure. However, the boot path cannot be freely specified in such a manner via the system monitoring mechanism  12 . 
     SUMMARY OF THE INVENTION 
     Accordingly, it is a general object of the present invention to provide a novel and useful remote boot method and mechanism and computer-readable storage medium, in which the problems described above are suppressed. 
     Another and more specific object of the present invention is to provide a remote boot method, a remote boot mechanism and a computer-readable storage medium, which can remotely specify an image of an Operating System (OS) that is a boot target, from a system management mechanism that manages the entire computer system. 
     Still another object of the present invention is to provide a remote boot method comprising the steps of loading an image of an operating system from a file apparatus that is connected to a computer system to a main memory of the computer system and starting the operating system; and remotely specifying an image of a boot target from a system monitoring mechanism that monitors the entire computer system. According to the remote boot method of the present invention, it is possible to remotely specify an image of an operating system that is a boot target, from a system management mechanism that manages the entire computer system. 
     A further object of the present invention is to provide a remote boot mechanism comprising a part configured to load an image of an operating system from a file apparatus that is connected to a computer system to a main memory of the computer system and starting the operating system; and a part configured to remotely specify an image of a boot target from a system monitoring mechanism that monitors the entire computer system. According to the remote boot mechanism of the present invention, it is possible to remotely specify an image of an operating system that is a boot target, from a system management mechanism that manages the entire computer system. 
     Another object of the present invention is to provide a computer-readable storage medium which stores a program for causing a computer to carry out a remote boot process, the program comprising a procedure causing the computer to load an image of an operating system from a file apparatus that is connected to a computer system to a main memory of the computer system and starting the operating system; and a procedure causing the computer to remotely specify an image of a boot target from a system monitoring mechanism that monitors the entire computer system. According to the computer-readable storage medium of the present invention, it is possible to remotely specify an image of an operating system that is a boot target, from a system management mechanism that manages the entire computer system. 
     Other objects and further features of the present invention will be apparent from the following detailed description when read in conjunction with the accompanying drawings. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  is a diagram showing an important part of a conventional computer system; 
         FIG. 2  is a diagram for explaining a path with which a boot firmware acquires boot information; 
         FIG. 3  is a diagram showing a computer system applied with an embodiment of the present invention; 
         FIG. 4  is a system block diagram showing an important part of the embodiment of the present invention; and 
         FIG. 5  is a flow chart for explaining an operation of the embodiment of the present invention. 
     
    
    
     DESCRIPTION OF THE PREFERRED EMBODIMENTS 
     A description will be given of embodiments of the remote boot method, remote boot mechanism and computer-readable storage medium according to the present invention, by referring to  FIGS. 3 through 5 . 
     According to the remote boot method, the remote boot mechanism and the computer-readable storage medium of the present invention, when an image of an Operating System (OS) that is a boot target exists in a plurality of file apparatuses and a control is to be carried out to boot one of the boot target images, this one boot target image is remotely specified from a system management mechanism that manages the entire computer system. 
     The computer-readable storage medium stores a program for causing a computer to carry out such a remote boot method and/or cause the computer to function as such a remote boot mechanism, and this program may be stored in any suitable recording medium capable of storing the program in a computer-readable manner. 
       FIG. 3  is a diagram showing a computer system applied with an embodiment of the present invention. In  FIG. 3 , those parts which are the same as those corresponding parts in  FIG. 1  are designated by the same reference numerals, and a description thereof will be omitted. In  FIG. 3 , a computer system  1  includes a main body part  11 , and a system monitoring mechanism  42  that monitors the entire computer system  1 . A plurality of Hard Disk Drives (HDDs)  2 - 1 ,  2 - 2 ,  2 - 3 , . . . , a CDROM or DVDROM (CDROM/DVDROM) drive  3 , and a network apparatus  4  are connected to the computer system  1 , as file apparatuses. The main body part  11  includes a ROM firmware  21 , a Read Only Memory (ROM) or Flash Memory (FMEM)  22 , a Non-Volatile RAM (NVRAM)  23  and a main memory  24 . In addition, the main memory  24  includes a boot firmware  241 , an Operating System (OS) loader program (hereinafter simply referred to as an OS loader)  242  and an OS  243 . 
     The ROM firmware  21  is written in a ROM or FMEM, and this ROM firmware  21  is started when the power of the computer system  1  is turned ON, to thereby execute a hardware analysis and initializing processes within the computer system  1 . Thereafter, an image of the boot firmware that is compressed and stored in the ROM or FMEM  22  within the computer system  1  is located into the main memory  24 , and the control is transferred to the boot firmware  241 . The boot firmware  241  includes a driver program (hereinafter simply referred to as a driver) for controlling boot target apparatuses (file apparatuses) that are supported by the computer system  1 , and executes the boot process by selecting the target apparatus that is to be actually booted, from the boot target apparatuses that are connected to the computer system  1 , depending on preset boot information. Normally, the boot firmware  241  boots the OS loader  242  for booting the target OS  243 . The boot firmware  241  does not need to be able to analyze the file system of the OS  243 . Since the OS loader  242  that corresponds to the OS  243  can analyze the file system of the OS  243 , the boot firmware  241  can recognize the location of the OS loader  242  in the boot target apparatus, and if this OS loader  242  can be booted, the OS  243  can thereafter be booted by this OS loader  242 . 
     In the computer system  1  shown in  FIG. 3 , the boot information is stored in the NVRAM  23 . The boot target apparatus that is to be automatically booted when starting the computer system  1  is determined from the plurality of boot target apparatuses that are connected to the computer system  1 , depending on the boot information that is stored in the NVRAM  23 . The boot information that is stored in the NVRAM  23  includes a BootXXXX variable, a BootOrder variable, and a BootNext variable, where “XXXX” denotes a hexadecimal number from “0000” to “FFFF”. The BootXXXX variable includes device path information indicating a location where the boot target apparatus is connected to the computer system  1 , and information related to a file position and a file name of the OS loader  242 . The BootOrder variable specifies an order in which the boot target apparatuses indicated by the plurality of BootXXXX variables are to be booted. The BootNext variable normally does not exist. But when the BootNext variable exists, the boot target apparatus that is specified by the BootXXXX variable indicated by the number set in the BootNext variable is booted, regardless of the BootOrder variable. When the control is transferred to the boot firmware  241 , the boot firmware  241  initializes various drivers for booting and carries out a probing process with respect to the HDDs  2 - 1 ,  2 - 2 ,  2 - 3 , . . . that are connected to the computer system  1 . Thereafter, the value of the portion “XXXX” of the BootXXXX variable is specified from the BootOrder variable of the NVRAM variables, and the boot target apparatus specified by the BootXXXX variable and the OS loader  242  are booted. 
     Accordingly, the following functions f 11 ) through f 13 ) are realized by the boot firmware  241 .
         f 11 ) A function of using drivers thereof for controlling the boot target apparatuses such as the HDDs  2 - 1 ,  2 - 2 ,  2 - 3 , . . . , the CDROM/DVDROM drive  3  and the network apparatus  4 , and booting the OS loaders  242  stored in the boot target apparatuses;   f 12 ) A function of storing the boot information, such as the device path information of the boot target apparatus and information of the image of the target OS, in the NVRAM  23 ; and   f 13 ) A function of reading the boot information stored in the NVRAM  23 , and selecting the boot target apparatus based on a boot priority order.       

     According to the functions f 11 ) through f 13 ) described above, the boot process of the OS  243  by the boot firmware  241  may be regarded as functions to determine the boot target apparatus based on the boot information that is preset in the NVRAM  23  and to boot the OS loader  242 . But in addition, the boot process of the OS  243  by the boot firmware  241  includes a so-called remote boot function which temporarily executes a boot process from a boot apparatus different from the boot information that is preset in the NVRAM  23 , only for the next boot process, based on information received from the system monitoring mechanism  42 . 
       FIG. 4  is a system block diagram showing an important part of this embodiment of the present invention. As shown in  FIG. 4 , the main memory  24  includes the boot firmware  241  and an OS install program  245 . The boot firmware  241  includes a remote boot control module  501  including an NVRAM variable flash module  500 , a boot manager  502 , a boot maintenance tool  503 , and NVRAM variables  301 . The system monitoring mechanism  42  includes a system monitoring mechanism remote boot manager  601 , a monitor program  602 , a network interface  603 , and system monitoring mechanism remote boot control variables  302 . 
     The monitor program  602  of the system monitoring mechanism  42  is connected to at least a part  10  of the main body part  11  within the computer system  1 . For example, the part  10  corresponds to an output function of a display part. Information monitored by the monitor program  602  can be output to this part  10 . The network interface  603  is connectable to the other computer system  31  via the network  30 . The system monitoring mechanism remote boot manager  601  specifies (or instructs) a remote boot using the system monitoring mechanism remote boot control variables  302 , and also manages the remote boot, in response to a request or instruction received from the part  10  or the other computer system  31 . 
     The remote boot control module  501  of the boot firmware  241  controls the remote boot that is specified (or instructed) from the system monitoring mechanism  42 , and the NVRAM variable flash module  500  copies the NVRAM variables  301  to the system monitoring mechanism remote boot control variables  302  within the system monitoring mechanism  42  when the NVRAM variables  301  are updated. The boot manager  502  manages the boot by the boot firmware  241 , including the remote boot. The boot maintenance tool  503  carries out a boot maintenance including updating of the NVRAM variables  301 . The OS install program  245  installs the image of the OS to the HDDs  2 - 1 ,  2 - 2 ,  2 - 3 , . . . and the like, and updates the NVRAM variables  301 . 
     In this embodiment, the BootXXXX variable, the BootOrder variable and the BootNext variable are all included not only in the NVRAM variables  301  that are managed by the boot firmware  241 , but also in the system monitoring mechanism remote boot control variables  302  that are managed by the system monitoring mechanism  42 , so that the boot target apparatus managed by the boot firmware  241  can also be specified by the remote boot that is specified from the remote monitoring mechanism  42 . The following controls c 1 ) through c 7 ) are made in order to maintain coherency of the boot information stored in the NVRAM  23  and the boot information stored in the remote monitoring mechanism  42 .
         c 1 ) The BootXXXX variable is made modifiable only at the NVRAM variables  301  by the boot maintenance tool  503  or the OS install program  245 , and non-modifiable at the system monitoring mechanism remote boot control variables  302 .   c 2 ) The remote boot control module  501  confirms whether or not all of the BootXXXX variables of the NVRAM variables  301  and the BootXXXX variables of the system monitoring mechanism remote boot control variables  302  perfectly match when the boot firmware  241  is started, and enables a boot depending on the remote boot that is specified only if the BootXXXX variables perfectly match. If the BootXXXX variables do not perfectly match even when the remote boot is specified by the system monitoring mechanism remote boot manager  601  of the system monitoring mechanism  42 , the remote boot control module  501  invalidates the remote boot that is specified, notifies to the system monitoring mechanism  42  an error message indicating that the remote boot that is specified has been invalidated since the boot information has been modified, and executes a normal boot process by the boot firmware  241 .   c 3 ) The BootOrder variable is made modifiable at both the NVRAM variables  301  and the system monitoring mechanism remote boot control variables  302 . When the remote boot is specified from the system monitoring mechanism  42  and the remote boot control module  501  confirms that the coherency of the BootXXXX variables is maintained, the BootOrder variable and the BootNext variable of the system monitoring mechanism remote boot control variables  302  are copied to the NVRAM variables  301 . In addition, with regard to the BootNext variable, after the BootXXXX variable of the boot target apparatus is determined, the BootNext variable if it exists in the NVRAM variables  301  is deleted regardless of whether or not the BootNext variable exists in the system monitoring mechanism remote boot control variables  302  (step S 11  shown in  FIG. 5  which will be described later). Accordingly, in this case, the BootOrder variable at the time when the remote boot is specified becomes valid, and it is possible to modify the priority order of the boot by the boot manager  502  from the system monitoring mechanism  42  (that is, the system monitoring mechanism remote boot manager  601 ).   c 4 ) The BootNext variable can be created at both the NVRAM variables  301  and the system monitoring mechanism remote boot control variables  302 . When the remote boot is specified from the system monitoring mechanism  42  and the remote boot control module  501  confirms that the coherency of the BootXXXX variables is maintained, the BootOrder variable and the BootNext variable of the system monitoring mechanism remote boot control variables  302  are copied to the NVRAM variables  301 . In addition, with regard to the BootNext variable, the BootNext variable if it exists in the NVRAM variables  301  is deleted regardless of whether or not the BootNext variable exists in the system monitoring mechanism remote boot control variables  302 . Accordingly, in this case, the BootNext variable at the time when the remote boot is specified becomes valid, and it is possible to temporarily specify the boot target apparatus from the system monitoring mechanism  42  (that is, the system monitoring mechanism remote boot manager  601 ).   c 5 ) In both cases where the remote boot is specified and not specified from the system monitoring mechanism  42 , the boot firmware  241  carries out the boot process according to the BootXXXX variable, the BootOrder variable and the BootNext variable of the NVRAM variables  301 , similarly to the conventional control. When the remote boot is specified and the coherency of the BootXXXX variables is maintained, the BootOrder variable and the BootNext variable are replaced by those that are specified by the remote boot, and the boot process is executed depending on the remote boot that is specified.   c 6 ) Generally, when specifying the remote boot, only the BootNext variable is usually set. Hence, the boot target apparatus of the next boot process can be specified temporarily, without modifying the boot information of the NVRAM variables  301  that are managed by the boot firmware  241 .   c 7 ) When the boot target apparatus is determined, the boot firmware  241  deletes the BootNext variable if it exists in the NVRAM variables  301 . The number of the BootXXXX variable indicating the boot target apparatus that is determined is set in a BootCurrent variable which is a memory variable, and this BootCurrent variable is notified to the system monitoring mechanism  42 . The BootCurrent variable is managed by the boot firmware  241 , but is not an NVRAM variable  301 , and thus, the BootCurrent variable is lost when the power of the computer system  1  is turned OFF. By checking the BootCurrent variable after the OS  243  is started, it is possible to judge by the OS  243  which boot target apparatus has been booted.       

       FIG. 5  is a flow chart for explaining an operation of this embodiment of the present invention. The process shown in  FIG. 5  is executed by the remote boot control module  501  of the boot firmware  241 . In  FIG. 5 , when the process of the remote boot control module  501  is started in a step S 1 , a step S 2  reads the system monitoring mechanism remote boot control variables  302  from the system monitoring apparatus  42 . A step S 3  reads the NVRAM variables  301  from the NVRAM  23 . A step S 4  decides whether or not the boot variables (BootXXXX variable, BootOrder variable and BootNext variable) of the NVRAM variables  301  have been updated. If the decision result in the step S 4  is NO, a step S 5  decides whether or not a remote boot is specified from the system monitoring mechanism  42 . 
     If the decision result in the step S 5  is YES, a step S 6  deletes the BootNext variable if it is included in the NVRAM variables  301 . A step S 7  copies the BootOrder variable and the BootNext variable included in the system monitoring mechanism remote boot control variables  302  to the NVRAM variables  301 . A step S 8  determines the BootXXXX variable of the boot target apparatus based on the BootXXXX variable, the BootOrder variable and the BootNext variable of the NVRAM variables  301 . If the decision result in the step S 5  is NO, the process advances to a step S 8 . 
     In the step S 5 , when the OS  243  is installed by the OS install program  245  or the boot maintenance is carried out by the boot maintenance tool  503 , and the reboot is not executed and the remote boot is specified in a state where the boot variables of the NVRAM variables  301  are updated, the remote boot is invalidated in this case, and the decision result in the step S 5  becomes NO. 
     On the other hand, if the decision result I the step S 4  is YES, a step S 9  copies the NVRAM variables  301  to the system monitoring mechanism remote boot control variables  302  within the system monitoring mechanism  42  by a flash process, and the process advances to the step S 8 . 
     After the step S 8 , a step S 10  notifies the BootCurrent variable to the system monitoring mechanism  42 . A step S 11  deletes the BootNext variable if this BootNext variable is included in the NVRAM variables  301 . A step S 12  boots the OS loader  242  that is specified by the BootXXXX variable that is determined in the step S 8 , and the process ends in a step S 13 . 
     In the embodiment described above, when the BootXXXX variable, the BootOrder variable and the BootNext variable exist as the NVRAM variables  301  and the remote boot is specified, the BootOrder variable and the BootNext variable of the system monitoring mechanism remote boot control variables  302  are copied to the NVRAM variables  301 , so that in the subsequent processes the bootXXXX variable of the boot target apparatus is determined from the bootXXXX variable, the BootOrder variable and the BootNext variable of the NVRAM variables  301  without being aware of the remote boot that is specified from the system monitoring mechanism  42 . But instead, it is possible to carry out a control by the remote boot control module  501 , as in each of modifications described hereunder. 
     In a first modification, when the remote boot is specified, the BootOrder variable of the system monitoring mechanism remote boot control variables  302  is copied to the NVRAM variables  301  only if this BootOrder variable is different from the BootOrder variable of the NVRAM variables  301 . With regard to the BootNext variable, a BootNextMemory variable is newly created as a memory variable, and not the NVRAM variables  301 , if the BootNext variable exists in the system monitoring mechanism remote control variables  302 , and the value of the BootNext variable of the system monitoring mechanism remote boot control variables  302  is copied to the BootNextMemory variable. 
     In the boot process carried out thereafter, the existence of the BootNextMemory variable is checked, and if the BootNextMemory variable exists, the BootXXXX variable of the NVRAM variables  301  specified by the value set in the BootNextMemory variable is regarded as the BootXXXX variable of the boot target apparatus. In a case where the NVRAM  301  is stored in a storage apparatus having a limit to the number of times the updating may be made, such as the flash memory, it is necessary to minimize unnecessary updating processes with respect to the NVRAM variables  301 . According to this first modification, if the boot specified using the system monitoring mechanism remote boot control variables  302  is only due to the BootNext variable, it is sufficient to create the BootNextMemory variable using the main memory  24  of the computer system  1  as the storage apparatus, and not the BootNext variable of the system monitoring mechanism remote boot control variables  302 , thereby making it possible to suppress the updating with respect to the NVRAM variables  301 . 
     In a second modification, the remote boot that is specified is limited to only the process at the time of the next boot, so as to guarantee the suppression of the unnecessary updating processes with respect to the NVRAM variables  301 . In this case, the system monitoring mechanism remote boot control variables  302  do not need to include the BootOrder variable, and only need to include the BootNext variable. Similarly as in the case of the first modification described above, the BootNextMemory variable is newly created as the memory variable, and not the NVRAM variables  301 , if the BootNext variable exists in the system monitoring mechanism remote control variables  302 , and the value of the BootNext variable of the system monitoring mechanism remote boot control variables  302  is copied to the BootNextMemory variable. Hence, in the boot process carried out thereafter, the existence of the BootNextMemory variable is checked, and if the BootNextMemory variable exists, the BootXXXX variable of the NVRAM variables  301  specified by the value set in the BootNextMemory variable is regarded as the BootXXXX variable of the boot target apparatus. Since the remote boot is specified using only the BootNext variable, it is possible to suppress the updating with respect to the NVRAM variables  301  when the remote boot is specified by the process of this modification. 
     In the embodiment described above, the BootXXXX variable is modifiable at the NVRAM variables  301 , and the remote boot that is specified is validated only when the coherency of the BootXXXX variables of the NVRAM variables  301  and the system monitoring mechanism remote boot control variables  302  is confirmed. But according to a third modification, in the computer system  1  in which the remote boot is specified using only the BootNext variable, the value of a specific BootXXXX variable is fixedly set with respect to a specific boot target apparatus. Hence, when the BootXXXX variable that is fixedly set in this manner in the computer system  1  is specified by the BootNext variable, this third modification validates the BootNext variable that is specified in the remote boot, regardless of whether or not the coherency of the BootXXXX variables is maintained. 
     In a fourth modification, the BootXXXX variable that may be specified by the BootNext variable in the remote boot is limited to the BootXXXX variable that is fixedly set in the computer system  1 , so that it is unnecessary to check or confirm the coherency of the BootXXXX variables of the NVRAM variables  301  and the system monitoring mechanism remote boot control variables  302 . In this case, although it is difficult to flexibly cope with the modification of the BootXXXX variable of the NVRAM variables  301 , it is possible to effectively reduce the processing time depending on the environment, such as under an environment where the boot target apparatuses that are connected to the computer system  1  are limited to a certain extent. 
     Therefore, the present invention is suited for application to computer systems that carry out the so-called boot process in which the image of the operating system is loaded from the file apparatus that is connected to the computer system to the main memory of the computer system and the operating system is started. 
     This application claims the benefit of a Japanese Patent Application No. 2005-078011 filed Mar. 17, 2005, in the Japanese Patent Office, the disclosure of which is hereby incorporated by reference. 
     Further, the present invention is not limited to these embodiments, but various variations and modifications may be made without departing from the scope of the present invention.