JP2002278913A - Information processing system and control method therefor - Google Patents

Abstract

PROBLEM TO BE SOLVED: To more softly and appropriately control electric connection/separation between peripheral equipment and a system main body and to improve the reliability of a system operation. SOLUTION: Isolation switch circuits 19 and 20 are inserted into IED buses 4 and 5. The isolation switch circuits 19 and 20 are turned on/off by the control of isolation signals which are individually inputted to the isolation switch circuits 19 and 20 from a switch control circuit 23. The isolation switch circuits 19 and 20 by the switch control circuit 23 are on/off-controlled not only by the detection of the installation/removal of disk devices 101 and 102 based on the potential change of a detection signal (DETECT) but also by an isolation flag which is set by an isolation register (REG) 181.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

[0001] 1. Field of the Invention [0002] The present invention relates to an information processing system and a control method thereof, and more particularly to an information processing system in which a peripheral device can be detachably attached to a system body and a control method for controlling the information processing system.

[0002]

2. Description of the Related Art Generally, in an information processing system such as a server computer, a peripheral device such as a disk device can be removably mounted in a drive bay or the like of a system body in order to add / replace the peripheral device. It is configured.

In this case, in order to realize a hot swap function (hot plug & hot swap) of attaching / detaching a peripheral device without turning off the power of the system body, a peripheral device and a controller for controlling the peripheral device are usually provided. A switch circuit is inserted on the signal line connecting the. By automatically controlling the on / off of the switch circuit when a peripheral device is installed / removed, noise can be prevented from entering the controller from the drive bay by the switch circuit that is off after the peripheral device is removed. When a peripheral device is mounted, a switch circuit that changes from an off state to an on state can automatically electrically connect the controller and the peripheral device.

The presence or absence of the peripheral device is detected by hardware logic, and the switch circuit is turned on / off by a detection signal from the hardware logic.

[0005]

However, in the case of the above-described configuration in which the on / off control of the switch circuit is performed by the detection signal from the hardware logic, while the peripheral device is mounted on the system body, Since the switch circuit is always on, it is not possible to electrically isolate the controller from the peripheral devices. Therefore, for example, even when a failure occurs in a peripheral device, the controller and the peripheral device remain electrically connected unless the peripheral device is removed from the drive bay. In this case, if the peripheral device is erroneously accessed, the erroneous data is read from the peripheral device, or the peripheral device does not respond to the access from the controller. In such a case, there is a danger that the access will not end, and in the worst case, the system may hang.

Further, conventionally, the detection of insertion / removal of a peripheral device is performed by a mechanism of polling a detection signal from the above hardware logic by software. For this reason, if a peripheral device is inserted and removed at a very short interval, even if the peripheral device is replaced, it cannot be detected depending on the polling interval. Therefore, even when, for example, a failed peripheral device is removed and a new peripheral device is attached, a process such as initialization necessary for using the new peripheral device cannot be automatically performed. There is a problem.

SUMMARY OF THE INVENTION The present invention has been made in view of the above circumstances, and enables more flexible and appropriate control of electrical connection / disconnection between a peripheral device and a system main body, and has sufficient operation reliability. It is an object of the present invention to provide an information processing system capable of obtaining the information and a control method thereof.

[0008]

In order to solve the above-mentioned problems, an information processing system according to the present invention comprises a peripheral device detachably mounted on a system main body, and an electric connection between the peripheral device and the system main body. Circuit, a first detection circuit for detecting the presence or absence of the peripheral device, and a circuit for controlling the connection circuit, the control circuit,
In each of the case where attachment or detachment of the peripheral device is detected based on the detection result of the first detection circuit, and the case where an electric connection / disconnection between the peripheral device and the system body is instructed. Accordingly, electrical connection / disconnection between the peripheral device and the system body by the connection circuit is controlled.

[0009] In this information processing system, not only when the mounting or removal of the peripheral device is detected by the first detection circuit, but also, for example, the electrical connection between the peripheral device issued from software and the system body. By the connection / disconnection instruction, the electrical connection / disconnection between the peripheral device and the system body by the connection circuit can be controlled. Therefore, even when the peripheral device is mounted, the peripheral device and the system main body can be electrically separated as necessary, so that, for example, when a failure occurs in the peripheral device, the system is automatically disconnected. By electrically separating the peripheral device from the system main body, a safe environment can be maintained without removing the peripheral device from the system main body.

[0010] Further, a second detection circuit for detecting a state change relating to the insertion / removal of a peripheral device with respect to the system main body is further provided. When the electrical connection is made, the first detection circuit detects that the peripheral device is attached,
And controlling the connection circuit to electrically connect the peripheral device and the system main body under a condition that a state change relating to insertion / removal of the peripheral device is detected by the second detection circuit. It is preferable to configure.

Thus, for example, when the peripheral device is electrically separated from the system main unit while the failed peripheral device is mounted, the replacement of the peripheral device with a new peripheral device is performed in a short time. Even if it is performed in the middle, it can be reliably detected and the peripheral device and the system body can be electrically connected, thereby automatically starting necessary processing such as initialization. It becomes possible.

[0012]

Embodiments of the present invention will be described below with reference to the drawings. FIG. 1 shows a configuration of an information processing system according to an embodiment of the present invention. This information processing system is, for example, a computer used as a server computer or the like.
PU 11, NORTH bridge 12, main memory 13, graphics controller 14, SOUTH bridge 1
5, IDE controller 16, various PCI devices 1
7. System management controller (SM controller) 1
8. Isolation switch circuit (SW) 19, 2
0, hot swap connectors 21 and 22, a switch control circuit 23, a status change detection circuit 24, and the like. Also, two disk devices (HDD) 1
01 and 102 are mounted as peripheral devices in a drive bay or a disk rack provided in the system main body of the computer. In the drive bay or the disk rack, two disk devices (HDD) 101,
102 can be detachably mounted.

The CPU 11 controls the operation of the computer, and executes an operating system loaded on the main memory 13, various applications, utility programs, and the like. The computer is also provided with a system management program for monitoring the operation of the system, and the program automatically detects various system failures and automatically notifies a manager of failures. Access to the main memory 13 by the CPU 11 is performed by a memory controller provided in the NORTH bridge 12.

The NORTH bridge 12 is a bus bridge that connects the processor bus 1 and the PCI bus 2 to each other, and a graphics controller 14 is connected to the NORTH bridge 12 via a video bus such as an AGP bus. The transfer of the display data from the main memory 12 to the graphics controller 14 is executed via a video bus.

The SOUTH bridge 15 is a bus bridge for interconnecting the PCI bus 2 with the I ² C bus 3 and other various buses, and functions as a PCI device. In addition to the SOUTH bridge 15, an IDE controller 16 for controlling IDE devices is connected to the PCI bus 2. IDE controller 16
And the hot swap connectors 21 and 22 provided in the drive bays or disk racks described above are connected by IDE buses 4 and 5, respectively.

Isolation switch circuits (SW) 19 and 20 are inserted into these IDE buses 4.5 as shown in the figure, and the hot swap connector 2 is connected via these isolation switch circuits 19 and 20.
Disk devices (HDD) 101 connected to
An electrical connection is made between 102 and the IDE controller 16.

Isolation switch circuits 19 and 20
The respective ON / OFF states are determined by the switch control circuit (SW control circuit) 23 and the isolation switch circuit 1
It is controlled by an isolation signal that is individually input to 9 and 20.

When the isolation switch circuit 19 is turned on, the IDE controller 16 and the disk device 101 are electrically connected via the IDE bus 4 connecting the IDE controller 16 and the hot swap connector 21. . On the other hand, when the isolation switch circuit 19 is turned off, the IDE controller 16 and the hot swap connector 21 are insulated and separated from each other.
The DE controller 16 and the disk device 101 are electrically disconnected. In this case, the IDE bus 4 is set to a high impedance state by the isolation switch circuit 19.

Similarly, the isolation switch circuit 2
0 is turned on, the IDE bus 5 connecting the IDE controller 16 and the hot swap connector 22
The IDE controller 16 and the disk device 102 via
Are electrically connected. On the other hand, when the isolation switch circuit 20 is turned off, the IDE controller 16 and the hot swap connector 22 are insulated and separated, and the IDE controller 16 and the disk device 102 are electrically separated. In this case, IDE bus 5
Are set to a high impedance state by the isolation switch circuit 20.

These isolation switch circuits 1
Reference numerals 9 and 20 are provided to realize a hot swap function (hot plug & hot swap). By automatically controlling the on / off of the isolation switch circuits 19 and 20 in accordance with the mounting / removal of the disk devices 101 and 102, the isolation switch circuit in the off state after the disk devices 101 and 102 are removed. 19 and 20, noise can be prevented from entering from the drive bay to the IDE controller 16, and when the disk devices 101 and 102 are mounted, the isolation switch circuits 19 and 20 change from the off state to the on state. Electrical connection can be automatically established between the disk devices 101 and 102.

A system management controller (SM controller) 18 monitors the operation of the computer system.
It is hardware logic for management, and is connected to the SOUTH bridge 15 via the I ² C bus.
The SM controller 18 has the following three types of I / Os as interfaces with the above-described system management program.
An O register is provided.

1) Isolation register (Isolatio)
n REG) 181 This is a register in which an isolation flag issued as an isolation instruction from the system management program is set. Isolation register (Isol
Two isolation flags respectively corresponding to the isolation switch circuits (SW) 19 and 20 are set in the (ation REG) 181. The isolation flag “H” indicates that the corresponding switch circuit is off, and the isolation flag “L” indicates that the corresponding switch circuit is on.

2) Status change register (Status)
(Change REG) 182 This is a register for notifying the system management program of a status change relating to the insertion and removal of each of the disk devices 101 and 102. 3) Detection register (Detect REG) 183 This is a register for notifying the system management program of whether or not each of the disk devices 101 and 102 is mounted.

In this embodiment, the disk drive 10 for each of the hot swap connectors 21 and 22 is
A detect signal (DETECT) individually indicating the presence / absence of the mounting of 1, 102 is generated by hardware.
That is, two detect signals (DETE) that are pulled up via a pull-up resistor are provided in the system body.
CT) line is prepared, one of the detect signal lines is connected to the hot swap connector 21 and the other detect signal line is connected to the hot swap connector 22. Disk device 10 connected to hot swap connector 21
1 is connected, a detection signal (DETEC) on the hot swap connector 21 side is
T) line changes from “H” to “L” level. Similarly,
When the disk device 102 is connected to the hot swap connector 22, a detect signal (DETEC) on the hot swap connector 22 side is
T) line changes from “H” to “L” level. The state change of each of these detect signal (DETECT) lines is set in a detection register (Detect REG) 183 as a DETECT flag indicating whether or not each of the disk devices 101 and 102 is mounted.

The on / off of each of the isolation switch circuits 19 and 20 by the switch control circuit (SW control circuit) 23 is controlled by two detect signals (DETEC).
T) Disk device 10 based on potential change of each line
The control is performed based on the detection of the attachment / detachment of the components 1 and 102 and the isolation flag set in the isolation register (Isolation REG) 181. This is to allow the connection / isolation of the IDE buses 4 and 5 to be freely controlled by instructions from software even when the disk devices 101 and 102 are connected.

The status change detection circuit 24 detects and latches a potential change of each of two detect signal (DETECT) lines, thereby obtaining the disk drive 10.
A state change relating to the insertion / removal state of each of the first and the second 102 is detected. The result of detection by the status change detection circuit 24 is set in a status change register (Status Change REG) 182 as a status change flag.

Next, a specific hardware configuration related to switch control will be described with reference to FIG.

Since the configurations of the IDE buses 4 and 5 are the same, all of the following explanations are based on the ID buses.
E bus 4, ie, isolation switch circuit (SW)
The description will be made focusing on the configuration related to the control on the 19th side.

As shown, the hot swap connector 2
Reference numeral 1 denotes a signal line for data input / output defined as an IDE bus 4 and a disk drive 1 from the system main body side.
01 (VCC, GN)
D) line and the above-described detect signal line are defined. The detect signal line is connected to the disk drive 10 via the hot swap connector 101a on the disk drive 101 side.
1 is connected to the ground terminal.

The isolation signal generation circuit 231 and the OR circuit 232 constitute the switch control circuit 23 described above. The isolation signal generation circuit 231 is a disk drive 1 using a detect signal (DETECT) line.
An isolation signal (Isolation signal) for controlling ON / OFF of the isolation switch circuit 19 is generated in response to the detection of attachment / detachment of the 01. That is, when the disk device 101 is removed (DETECT is at the “H” level), the isolation signal generation circuit 231 outputs an “H” level isolation signal indicating electrical disconnection, and the disk device 101
Is installed (DETECT is "L" level)
Outputs an "L" level isolation signal indicating electrical connection.

An output from the isolation signal generating circuit 231 is connected to one input of an OR circuit 232, and the other input of the OR circuit 232 is connected to an output port P1 of the system management controller 18. The output port P1 is connected to an isolation register (Isolation R).
EG) 181 to output an “H” or “L” level isolation signal corresponding to the isolation flag. As a result, the electrical connection / disconnection between the disk device 101 and the system main unit by the isolation switch circuit 19 can be performed not only when the attachment or detachment of the disk device 101 is detected but also by an instruction from the system management program. Can be controlled. Therefore, the isolation signal generation circuit 23
By setting the “H” level isolation flag from the OR circuit 232 even when the “L” level isolation signal is output from 1, that is, while the disk device 101 is mounted. “H”
Since a level isolation signal can be output, the disk device 101 and the system body can be electrically separated. Therefore, for example, when a failure occurs in the disk device 101, the disk device 1 is automatically
01 and the system itself,
A safe environment can be maintained without removing the disk device 101 from the system main body.

The system management controller 18 is provided with input ports P2 and P3 as shown.
The input port P2 sends a detection flag indicating attachment / detachment of the disk device 101 in response to a change in the detection signal DETECT to a detection register (De.
tect REG) 183. When the disk device 101 exists, the detection flag becomes “L”, and when it does not exist, the detection flag becomes “H”.

The input port P3 is used to set a status change relating to the insertion / removal state detected by the status change detection circuit 24 as a status change flag in a status change register (Status Change REG) 182. The status change flag = “H” indicates that a change has occurred in the insertion / removal state of the disk device 101, and the status change flag = “L” indicates that no change has occurred in the insertion / removal state of the disk device 101.

FIG. 3 shows a configuration example of the disk device 101.

The disk device 101 has a structure in which an HDD unit 101d having an IDE interface is housed in a housing case 101e having a hot swap connector 101a. HDD unit 101d
Is a disk drive unit including a disk medium and a mechanism for driving the disk medium. The hot swap connector 101a is a hot swap connector 2 on the system body side.
Power supply pins (VCC, GND) for receiving power supplied to the disk device 101 from the system body in addition to signal pins for data input / output defined as the IDEIDE bus 4 And the above-mentioned pins for the detect signal are defined. In this case, the power supply pins are formed longer than the other signal pins. This is because the disk device 101 is connected to the hot swap connector 2
1, when power is first supplied to the HDD unit 101d, the HDD unit 101d
Is to stabilize the operation more quickly. Further, even when the disk device 101 is detached from the hot swap connector 21, the operation of the HDD unit 101d can be stabilized until the end.

The hot swap connector 101a is connected to a printed circuit board (PCB) 101b, and a pin for a detect signal is grounded on the printed circuit board (PCB) 101b. IDE in hot swap connector 101a
Signal pins for the printed circuit board (PCB) 101b and H
The HDD unit 101d is connected via a relay cable 101c connecting the IDE unit to the IDE connector of the DD unit 101d.
IDE connector. Power pins (VCC, GND) in the hot swap connector 101a
Then, it is connected to a power terminal of the HDD unit 101d through a power cable.

Next, a specific hardware configuration of the status change detection circuit 24 will be described with reference to FIG.

The status change detection circuit 24 comprises a pulse generation circuit 241 and a D flip-flop 242 as shown. The pulse generation circuit 241 is a circuit for detecting a rising or falling of the detect signal DETECT and generating a pulse signal indicating that a state change relating to the insertion / removal of the disk device 101 has occurred. , EXOR circuit 241b. EXOR circuit 241
b is connected to the clock input terminal CLK of the D flip-flop 242.
The D input terminal 42 is connected to the power supply VCC. Thus, each time a pulse signal is generated from the pulse generation circuit 241, the "H" level value of the D input terminal is latched by the D flip-flop 242, and the "H" level signal is output from the Q output. The Q output signal of the D flip-flop 242 is input to a status change register (Status Change REG) 182 as a status change signal. The status change register (Stat
us REG) 182, the reset flag is set by software,
Of the D flip-flop 242 is cleared.

In this embodiment, the status change flag of the status change register (Status Change REG) 182 and the detection register (Dete
By using the detection flag of (ctREG) 183, the insertion and removal of the disk device 101 can be correctly detected by software.

FIG. 5 shows the relationship between the status change flag and the detection flag and the contents of state recognition by software in that case.

1) Status change flag = “L”,
Detection flag = “L” When this state is acquired by polling by the system management program, the system management program does not insert or remove the disk device 101 and
1 recognizes that it is still attached.

2) Status change flag = "L",
Detection flag = “H” When this state is acquired by the system management program by polling, the system management program does not insert / remove the disk device 101 and the disk device 10
1 recognizes that it has been removed.

3) Status change flag = "H",
Detection flag = “L” When this state is acquired by the system management program by polling, the system management program determines that the disk device 101 is currently mounted and the disk device 1
It is recognized that a change has occurred in the insertion / extraction state of No. 01. In this case, the system management program determines that a new installation or replacement of the disk device 101 has been performed, and
01, for example, initialization of the disk device 101, and when RAID1 mirroring was performed between the disk device 101 and the disk device 102, the disk device 102
The RAID reconfiguration process is performed by copying a data file to a storage device. Of course, the RAID reconfiguration process accompanying the addition or replacement of the disk device 101 is performed not only when the RAID1 mirroring is used but also when the RAID5 is used.

Further, the system management program checks the detection flag obtained at the time of the previous polling, if necessary, to check the disk device 101.
Is newly mounted (previous detection flag = “H”), or whether the disk device 101 has been replaced (previous detection flag = “L”). In the case where the previous detection flag = “L”, strictly speaking, there is a possibility of both replacement with another disk and removal and insertion of the same disk. And the latter can be distinguished.

4) Status change flag = "H",
Detection flag = “H” When the system management program acquires this state by polling, the system management program recognizes that the disk device 101 is currently mounted, and that the insertion / removal state of the disk device 101 has changed. I do. In this case, the system management program determines that the disk device 101 has been detached or has been temporarily attached by insertion / removal operation and then removed again. Of course, also in this case, it is possible to determine whether the operation is the removal of the disk device 101 or the insertion / removal operation by referring to the previous detection flag as necessary.

Next, referring to the flowchart of FIG.
A series of processing procedures executed by the system management program will be described.

When the system management program detects that a failure has occurred in the disk device 101 or 102 during the operation of the system (step S101), the system management program notifies the administrator of the failure by sending a buzzer sound or e-mail (step S102). ), The isolation flag corresponding to the failed disk device is set to “H” level (step S103). Thus, the isolation switch circuit on the IDE bus 4 or 5 side corresponding to the failed disk device is turned off, and the failed disk device and the IDE controller 16 are electrically isolated. As a result, access to the failed disk device is automatically prohibited before the administrator removes the failed disk device, and a failure due to access to the failed disk device is prevented from occurring. Can be prevented.

Thereafter, the system management program executes a detection register (Detect REG) 183 and a status change register (Status Change REG) 18.
2 is periodically polled, and waits until the detection flag and the status change flag corresponding to the disk device for which the isolation flag is set to the “H” level become “L” and “H”, respectively. When the administrator receiving the disk failure notification removes the disk device and replaces it with a new disk device, the detection flag =
“L” and the status change flag = “H”. At this point, the isolation signal is still maintained at “H” by the “H” level isolation flag, so that even if the detection signal changes to “L”, the O
The R circuit 232 outputs an “H” level isolation signal indicating that the switch is OFF.

When the system management program recognizes that the detection flag and the status change flag are “L” and “H” by polling (YES in step S 104), the system management program stores the reset flag in the status change register (Status Change REG) 182. Is set to clear the contents held in the status change detection circuit 24 (step S105),
The “H” level isolation flag is set to “L” level (step S106). As a result, the corresponding isolation switch circuit is turned ON, and the replaced disk device and the IDE controller 16 are electrically connected.

Thereafter, the system management program performs processing such as initialization of the disk device and copying of a data file necessary for the RAID reconfiguration processing (step S1).
07).

As described above, according to the present embodiment, when a failure of a disk device is detected, it is automatically detected by the I / O device.
It can be electrically disconnected from the DE controller 16, and after that, even if replacement with a new disk device is performed in a short time, it is reliably detected and the disk device and the IDE controller 16 are replaced. Can be electrically connected, and necessary processing such as initialization can be automatically performed.

The present invention is not limited to the above-described embodiment, and can be variously modified in the implementation stage without departing from the gist of the invention. For example, in the above embodiment, the connection /
Although the separation has been described, the method of the present invention can be used to control connection / disconnection between any peripheral device requiring a hot swap and the system body. Further, the disconnection control of the IDE bus by software may be performed by software not only when a failure of the disk device is detected but also when an explicit instruction is given from a user, for example. .

Further, the above embodiments include inventions at various stages, and various inventions can be extracted by appropriately combining a plurality of disclosed constituent elements. For example, even if some components are deleted from all the components shown in the embodiment, the problem described in the column of the problem to be solved by the invention can be solved, and the effects described in the column of the effect of the invention can be solved. Is obtained, a configuration from which this configuration requirement is deleted can be extracted as an invention.

[0054]

As described above, according to the present invention, the electrical connection / disconnection between the peripheral device and the system main body can be more flexibly and appropriately controlled, and the operation reliability can be sufficiently improved. Improvement can be achieved.

[Brief description of the drawings]

FIG. 1 is a block diagram showing a configuration of an information processing system according to an embodiment of the present invention.

FIG. 2 is an exemplary view showing a specific circuit configuration around an isolation switch circuit provided in the embodiment.

FIG. 3 is an exemplary view showing the configuration of a disk device used in the embodiment.

FIG. 4 is a diagram showing a configuration of a status change detection circuit used in the embodiment.

FIG. 5 is an exemplary view for explaining the relationship between a status change flag and a detection flag and state recognition by software in that case in the embodiment;

FIG. 6 is an exemplary flowchart for explaining the operation of the system management program according to the embodiment;

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 11 ... CPU 13 ... Main memory 15 ... IDE controller 18 ... System management controller 19, 20 ... Isolation switch circuit 21, 22 ... Hot swap connector 23 ... Switch control circuit 24 ... Status change detection circuit 181 ... Isolation register 182 ... Status Change register 183 ... detection register

Claims (7)

[Claims] A peripheral device detachably mounted on a system main body; a circuit for electrically connecting the peripheral device to the system main body; and a first detecting unit for detecting whether or not the peripheral device is mounted. A detection circuit, and a circuit that controls the connection circuit, wherein the control circuit detects when attachment or detachment of the peripheral device is detected based on a detection result of the first detection circuit, and the peripheral device Controlling the electrical connection / disconnection between the peripheral device and the system main unit by the connection circuit according to each of the cases where the electrical connection / disconnection with the system main unit is instructed. Characteristic information processing system. 2. The system according to claim 1, further comprising: a second detection circuit configured to detect a change in state of the peripheral device with respect to insertion / removal of the peripheral device with respect to the system main body. When the main body is electrically disconnected from the main body, the first detection circuit detects that the peripheral device is mounted, and the second detection circuit detects a state related to insertion and removal of the peripheral device. 2. The information processing system according to claim 1, wherein the connection circuit is controlled to electrically connect the peripheral device and the system main body on a condition that a change is detected. 3. A circuit for generating a signal indicating that a state change relating to insertion / removal of the peripheral device has occurred in response to attachment / detachment of the peripheral device to / from the system main body, respectively, 2. The information processing system according to claim 1, further comprising: a circuit for holding the generated signal. 4. The peripheral device is provided with a disk drive unit, a storage case for storing the disk drive unit, a relay connector provided in the storage case, connected to the system body, and provided in the disk drive unit. A disk device including a relay cable connecting between a connector and the relay connector, wherein the relay connector defines a signal pin and a power pin for data input / output, and the power pin is the signal pin. 2. The information processing system according to claim 1, wherein the information processing system has a longer pin length. 5. The connection / disconnection instruction is issued from a program executed on the information processing system, and when a failure of the peripheral device is detected, the peripheral device and the system body 2. The information processing system according to claim 1, wherein an instruction indicating electrical disconnection from the program is issued from the program. 6. A peripheral device detachably mounted on a system main body, a circuit for electrically connecting the peripheral device to the system main body, and a first device for detecting whether or not the peripheral device is mounted. A detection circuit, a circuit for electrically connecting the peripheral device and the system body by the connection circuit when the attachment of the peripheral device is detected by the first detection circuit; When an electrical disconnection from the system main body is instructed, the peripheral circuit is electrically disconnected from the system main body by the connection circuit in a state where the peripheral device is mounted on the system main body. A circuit; a second detection circuit for detecting a state change relating to insertion and removal of the peripheral device with respect to the system main body; and a peripheral device and the system main unit based on the disconnection instruction. After electrically disconnecting from the body, it is determined whether the peripheral device has been replaced or a new peripheral device has been installed based on the detection results of the first and second detection circuits, and based on the determination result. Means for controlling electrical connection / disconnection between the peripheral device and the system main body. 7. A control method for controlling an information processing system in which a peripheral device can be detachably attached to a system main body, wherein a step of detecting whether or not the peripheral device is attached; If detected, electrically connecting the peripheral device to the system main unit; and, if the peripheral device is mounted to the system main unit, an electric connection between the peripheral device and the system main unit. Electrically disconnecting the peripheral device and the system main body based on a temporary disconnection instruction, and after electrically disconnecting the peripheral device and the system main body based on the disconnection instruction, Replacement of a peripheral device or replacement of a new peripheral device based on a change in state of insertion and removal of the peripheral device with respect to the system To determine the presence or absence of wear, the control method for an information processing system, characterized by comprising the step of controlling the electrical connection / disconnection between the system body and the peripheral device based on the determination result.