JPH10161919A - Information processing system, and information input/ output control method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To attain the matching of protocol between plural information processors having mutually different input/output interfaces in the case of accessing the same logic volume by making it possible to easily share data at high speed. SOLUTION: A 1st information processor 300 and a 2nd information processor 400 connected through a 1st input/output interface 310 and a 2nd input/output interface 410 to a disk controller 100 share data by accessing the same logic volume 200. The disk controller 100 is provided with a common memory 140 including a logic volume managing block 510 having an interface occupation flag 511 and before starting processing an interface protocol, the interface occupation flag 511 is checked. When the logic volume 200 is under the control of another interface, protocol processing is not performed but a busy state or the like is reported.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a magnetic disk drive and an information input / output method for a magnetic disk drive, and more particularly to a magnetic disk drive and an information input / output method which is effective when applied to a plurality of information processing systems having different input / output interfaces. Technology.

[0002]

2. Description of the Related Art In recent years, information processing systems of different scales, for example, a large general-purpose computer system and a small system such as a workstation or a personal computer have been individually used due to advancement of information processing technology and networking. Is shifting to a form of sharing and using data possessed by mutual systems.

However, these information processing systems having different scales have different interfaces for controlling data input / output. For example, in a large-scale general-purpose computer system, a channel interface which is a standard of IBM Corporation is well known. For small systems such as stations and personal computers, SCSI (Small Com
(Puter System Interface) is almost standard. Regarding SCSI, for example, CQ Publisher, Seiichi Sugaya, “SCSI-
2 Detailed explanation ”, the channel interface is used as the interface of the IBM magnetic disk drive.
It is described in Iwanami Shoten's book, Nobumasa Takahashi et al., "Functions and Structure of Operating Systems".

[0004] As a method of sharing data between information processing systems having different input / output interfaces, a method of transferring data via a magnetic tape or a method of controlling another computer processing apparatus via a network is used. Methods of accessing data in an underlying external storage device are known.

[0005] Also, Japanese Patent Application Laid-Open No. 2-43618 discloses that
A method of exclusively controlling a shared disk device between computer systems when a plurality of computer systems share the disk device is described.

[0006]

However, the method of transferring data via a magnetic tape requires manual intervention and is not practical.

A method of accessing data in an external storage device under the control of another computer processing device via a network increases network traffic and increases the CPU, memory, and I / O of another computer.
The use of resources such as the / O path is not preferable.

Further, Japanese Patent Application Laid-Open No. 2-43618 discloses that
The interface of a plurality of computer systems is the same channel interface, and a technique of sharing a disk device by a plurality of computer systems having different interfaces is not disclosed.

An object of the present invention is to provide a technique for quickly and easily sharing data between a plurality of information processing apparatuses having different input / output interfaces.

Another object of the present invention is to provide a technique for solving consistency between interface protocols when a plurality of information processing apparatuses try to access the same logical volume via different input / output interfaces. To provide.

[0011]

[Means for Solving the Problems]

(1) An information processing system according to the present invention includes a first information processing apparatus having a first input / output interface and a second information processing apparatus having a second input / output interface having a different specification from the first input / output interface. Information processing device, a disk controller provided with at least first and second input / output interfaces, and a logical volume consisting of a single area or a plurality of areas placed under the control of the disk controller A disk device including a logical volume, wherein the first and second information processing devices access the same area or logical volume via the first and second input / output interfaces, respectively. And has the logic to share data.

According to such an information processing system, the first and second information processing devices access the same area or logical volume via the first and second input / output interfaces, respectively, and transfer data. Since the shared logic is provided, a plurality of information processing apparatuses having different input / output interfaces can share data quickly and easily. That is, the data is shared by accessing data recorded in the same area or logical volume from the first and second information processing devices. As a result, the troublesome manual work is omitted, and without using computer resources such as a network,
Data can be shared between a plurality of information processing apparatuses having different input / output interfaces easily and quickly.

The input / output interface includes:
One can be exemplified by a SCSI interface and the other can be exemplified by a channel interface.

Further, the first and second information processing apparatuses can recognize the logical volume as a logical unit via a SCSI interface and as a logical volume via a channel interface.

(2) The information processing system according to the present invention is the information processing system according to the above (1), wherein the first information processing device accesses the area or the logical volume when the second information is accessed. When the processing unit attempts to access the area or the logical volume at the same time, the area or the logical volume of the first logical, the first or the second information processing apparatus under the control of the first or the second input / output interface. A second logic for stopping one, a third logic for stopping one program of the first or second information processing device,
A fourth logic for serializing access of the first information processing device and access of the second information processing device, an access path between the first information processing device and the first input / output interface,
A fifth logical unit that disables an access path between the first information processing device and the second input / output interface or an access path between the first and second information processing devices and an area or a logical volume. And means for prohibiting simultaneous access to the area or the logical volume of the first information processing device and the second information processing device by executing any one of the logics.

According to such an information processing system, when the first information processing apparatus accesses the area or the logical volume while the second information processing apparatus tries to access the area or the logical volume at the same time. , By executing any one of the first to fifth logics,
Means for prohibiting simultaneous access to the area or logical volume of the second information processing apparatus and the second information processing apparatus, it is possible to ensure consistency between different interface protocols.

(3) An information input / output control method for an information processing system according to the present invention is the information input / output control method for an information processing system according to the above (1) or (2), wherein Alternatively, when a disk management information storage area for storing disk management information corresponding to a logical volume is provided, and protocol processing or reserve processing is to be performed on an area or a logical volume from the first input / output interface, refer to the disk management information. When the area or the logical volume is in a free state by referring to the disk management information, a protocol processing from the first input / output interface to the area or the logical volume or a reserve processing to the area or the logical volume is performed. Is executed, the second step is to refer to the disk management information When it is determined that the area or the logical volume is being accessed or reserved by the second input / output interface, the first information processing apparatus is informed that the area or the logical volume is busy. Or a third step of ending the protocol processing or the reserve processing after reporting that the reservation is being made.

According to such an information input / output control method for an information processing system, a disk management information storage area is provided,
Referring to the disk management information (first step), as a result, if the area or the logical volume is in an empty state, the protocol processing or the reserve processing for the area or the logical volume is executed (second step), If it is not empty, the protocol processing or the reserve processing is terminated after reporting that the apparatus is busy or reserved (third step), so that a higher level of consistency between interfaces can be achieved. That is, the occupation state of the area or the logical volume by one input / output interface is secured by the disk management information, and the environment in which the recording / reproducing process is normally performed by the information processing apparatus being accessed is prepared, while the other input / output interface is used. It reports the busy or reserved status to the information processing apparatus that is to be accessed from the interface, and makes it possible to process an access failure to an area or a logical volume, thereby achieving consistency between the interfaces.

The storage of the disk management information can be provided not only by the disk controller but also from outside the disk controller. In addition, the disk management information may be provided not only for one area or logical volume, but also for a plurality of areas or groups of logical volumes.

When an area or a logical volume is reserved by one input / output interface, reserve, release, or reset processing can be performed equivalently or with priority from the other input / output interface. Can also be set to Conversely, it is needless to say that the reserve, release, or reset processing from the other input / output interface can have no effect on the reserved state of one input / output interface.

[0021]

Embodiments of the present invention will be described below in detail with reference to the drawings.

(Embodiment 1) FIG. 1 is a block diagram showing an example of an information processing system according to an embodiment of the present invention, and FIGS. 2 to 5 are block diagrams showing main parts thereof. It is.

As shown in FIG. 2, the computer system according to the first embodiment includes a disk controller 100, a logical volume 200, a first information processor 300, and a second information processor 300.
It has an information processing device 400.

The disk control device 100 is connected to the first information processing device 300 via the first input / output interface 310.
And via the second input / output interface 410
It is connected to the information processing device 400 and to the logical volume 200 via the path 210.

The first input / output interface 310 and the second input / output interface 410 are respectively connected to the first information processing device 3.
It is an input / output interface compatible with the second information processing device 400 and the second information processing device 400, and has mutually different specifications. However, both disk control devices 100
The first information processing device 30
0 and the second information processing apparatus 400 are connected to the same logical volume 20 via the first input / output interface 310 and the second input / output interface 410 having different specifications.
0 can be accessed.

As shown in FIG. 3, the disk control device 100 includes a first input / output interface control unit 110, a second input / output interface control unit 120, a drive interface unit 130, and a common memory 140. They are connected via an internal bus 150.

First input / output interface controller 110
Controls the first input / output interface 310, and the second input / output interface control unit 120
The input / output interface 410 is controlled.

The drive interface unit 130 is provided for each logical volume 200 and controls the drive of the disk unit via the path 210.

The common memory 140 includes, as shown in FIG.
It includes a logical volume management table 500 for managing logical volumes. The logical volume management table 500 has at least one or more logical volume management blocks 510, and one logical volume management block 510 is used to manage one logical volume 200.

The logical volume management block 510 includes:
As shown in FIG. 5, an interface in-use flag 511 indicating that the input / output interface is in use is included. The interface in use flag 511 indicates that the logical volume 200 indicates that the first input / output interface 310
In use through the second input / output interface 4
It is possible to memorize the status of use or non-use through 10.

FIG. 1 shows a configuration diagram of an information processing system in which the configurations shown in FIGS. 2 to 5 are integrated.

A control program 111 for the first input / output interface 310 is stored in the first input / output interface control unit 110, and a control program for the second input / output interface 410 is stored in the second input / output interface control unit 120. 121 are stored.

The common memory 140 stores a logical volume management block 510 of the logical volume 200. The logical volume management block 510 includes an interface busy flag 511 and a logical volume management block for the first input / output interface 310. 515, second
A logical volume management block 516 for the input / output interface 410 is included.

Here, the control program 111 and the logical volume management block 515 may be dedicated to the first input / output interface 310. The control program 121
The logical volume management block 516 may be dedicated to the second input / output interface 410.

Next, the first input / output interface 310 and the second input / output interface 4 will be described with reference to FIGS.
The means for sharing and accessing the same logical volume 200 via 10 will be described. FIG. 6 is a flowchart illustrating an example of an information input / output control method used in the information processing system according to the first embodiment. FIGS. 7 and 8 illustrate a setting process and a reset process of the interface in-use flag 511. It is a flowchart for performing.

When the first information processor 300 accesses the logical volume 200, the disk controller 1
The control program 111 in 00 starts protocol processing. In the protocol processing, the interface in-use flag 511 on the common memory 140 is checked (step 601).

As a result, the first input / output interface 31
If the first information processing device 300 connected via the “0” is using the logical volume 200, the protocol processing is performed (step 602), and the processing ends.

Here, the protocol processing in step 602 can be performed using the control program 111 and the logical volume management block 515.

As a result of checking the interface in-use flag 511, the second information processing apparatus 400 connected via the second input / output interface 410
If 00 is being used, a busy report, a protocol rejection report, a normal end report by performing a NOP operation, or a pseudo response to the first information processing apparatus 300 (step 603), and the process ends. .

Although the access from the first information processing apparatus 300 has been described here, the processing for the access from the second information processing apparatus 400 can be performed in the same manner as the processing for the access from the first information processing apparatus 300. Needless to say.

As shown in FIG. 7, the setting process of the interface in-use flag 511 is performed for the corresponding logical volume 2.
When 00 is unused, it can be performed in the processing of the first-arrived interface protocol (step 604). The reset process of the interface in-use flag 511 can be performed at the end of the process of the interface protocol as shown in FIG. 8 (step 605). Furthermore, the interface busy flag 5
The setting process or the reset process of the disk controller 100 is performed from outside the disk controller 100 by, for example, a service processor (SV
P), a switch, or a protocol input from an information processing apparatus.

As described above, the first and second information processing apparatuses 300 and 400 try to access the same logical volume 200 via the first and second input / output interfaces 310 and 410 having different specifications. At this time, matching between interfaces can be achieved. Here, when one of the interfaces is a SCSI interface, a busy status report can be made as a report for the command, and when one of the interfaces is a channel interface, the operating status can be reported as a report for the command.

FIG. 9 is a state diagram showing how the status of a logical volume is shown to another interface when the logical volume is being accessed. For example,
When the first I / O interface 310, which is a SCSI interface, is accessing the logical volume 200, the second I / O interface 410, which is a channel interface, appears to be in use. If the second I / O interface 410 is accessing the logical volume 200, the first I / O interface 310, which is a SCSI interface, can appear to report a busy status.

According to the information processing system and the information input / output control method of the first embodiment, the disk control device 100
Different first and second input / output interfaces 31
0 and 410 are provided, so that the same logical volume 200 under the disk controller 100 can be accessed via different first and second input / output interfaces 310 and 410. Thus, when exchanging data between the first and second information processing apparatuses 300 and 400, a complicated manual operation such as using a magnetic tape can be avoided. Also, compared to the case where the shared data is accessed via the network between the first and second information processing devices 300 and 400, the shared data is directly accessed without passing through another information processing device or the network. Can be. As a result, computer resources such as an information processing device and a network can be effectively used.

In the first embodiment, the case where the disk controller 100 has two input / output interfaces and two information processing devices has been described. Needless to say, even if the number is three or more, interface matching can be achieved.

In the first embodiment, the case where the number of logical volumes 200 is one is illustrated. However, a plurality of logical volumes may be grouped, and a common memory 140 may be provided for each group.

In the first embodiment, when the logical volume 200 is used by one of the input / output interfaces, the logical volume 200 is placed under the control of the input / output interface, and the logical volume 200 is used by the other input / output interface. In the above example, consistency between different input / output interfaces is controlled by restricting access to one of the information processing devices. Device and disk controller 100 or logical volume 2
By disabling the I / O path between 00 and 00, only a single input / output interface can access only the same logical volume 200 for a certain period of time. As a result, the logical volume 2 via different input / output interfaces
Exclusive control of the use of 00 can be enabled. In such a case, exclusive control of the logical volume 200 can be easily realized without particularly complicated protocol processing.

Further, by performing communication between the information processing apparatuses so as to prevent one of the information processing apparatuses from accessing the disk control apparatus 100 or the logical volume 200, a single input / output is performed for a certain period of time. Only the access via the interface may be performed on the same logical volume 200. As a result, exclusive control of use of the logical volume 200 via different input / output interfaces can be performed. In this case, the access of the other information processing apparatus can be made to stand by by the communication until the access of one information processing apparatus ends, and the processing can be sequentially performed.

(Embodiment 2) The information processing system according to Embodiment 2 enables exclusive control of a logical volume by enabling a reserve / release function for a logical volume across different input / output interfaces. It is assumed that.

FIG. 10 is a conceptual diagram showing an example of the logical volume management block according to the second embodiment. As shown in FIG. 10, a common reserve flag 512 common to different input / output interfaces is provided in the logical volume management block 510. The other configuration is the same as that of the first embodiment, and the description is omitted.

Next, reserve command processing, release processing, normal command processing, and forced release of reserved state in the information processing system according to the second embodiment will be described with reference to FIGS.

FIG. 11 is a flowchart for explaining the reserve command processing. The reserve command processing checks the common reserve flag 512 (step 606), and if the logical volume 200 is free,
The local host (first or second)
The ID of the information processing device is recorded (step 607), and the process ends. If the logical volume 200 is in use, a reservation failure is reported to the host (step 60).
8), end the process.

FIG. 12 is a flowchart for explaining the release processing. In the release processing, it is checked whether the common reserve flag 512 is equal to the own host ID (step 610), and if they are equal, the common reserve flag 512 is cleared (step 611). If they are not equal, another host reports that it is being reserved. (Step 61
2), end the process.

FIG. 13 is a flowchart for explaining normal command processing. First, the command processing
It is checked whether or not the common reserve flag 512 is equal to the own host ID (step 613). If they are equal, command processing is performed (step 614). If they are not equal, another host reports that it is being reserved and does not perform command processing. (Step 615), the process ends.

It is also possible to forcibly release the reserved state by another host. FIG.
It is a flowchart for demonstrating the forced release process of a reserve state. The forced release processing clears the common reserve flag 512 or sets the common reserve flag 5
12 is executed by writing the host ID of the host (step 609).

FIG. 15 is a state diagram showing the handling of the reserve function and the forced release function when the SCSI interface and the channel interface share a logical volume.

S as the first input / output interface 310
When the logical volume 200 is reserved by the CSI interface, the channel interface as the second input / output interface 410 makes the logical volume 200 appear to be in the reserved state. here,
When a command to release reserve (UNCON RSV) is input to the channel interface, the above-described forced release processing is performed to release the reserved state by the SCSI interface, and Bu is sent to the SCSI interface.
s A response corresponding to the Device Reset can be returned.

On the other hand, the logical volume 20 is provided by the channel interface as the second input / output interface 410.
When 0 is reserved, the SCSI interface that is the first input / output interface 310 makes the logical volume 200 appear to be in the reserved state. Here, when a command (Bus Device Reset) for forced reserve release is input to the SCSI interface, the reserve release by the channel interface is released by performing the above-described forced release processing, and a response corresponding to UNCON RSV is sent to the channel interface. Can be returned.

According to the information processing system and the information input / output control method of the second embodiment, the reserve / release function for the logical volume 200 can be enabled across different input / output interfaces. The exclusive control of the logical volume 200 can be performed by utilizing the reserve / release function.

It is to be noted that there is a method in which the reserve / release function of the logical volume is not affected mutually between different input / output interfaces, and is closed in the input / output interface. Such a method, as shown in FIG.
This is possible by having a reserve flag for the logical volume 200 for each interface. That is, FIG.
In the logical volume management block 510, the first
Reserve flag 513 of input / output interface 310
And the reserve flag 514 of the second input / output interface 410 can be included.

FIG. 17 is a state diagram showing the handling of the reserve function and the forced release function when the reserve function of the logical volume 200 is independent without affecting the SCSI interface and the channel interface. Reserve flags 513, 5 for each interface
14, even if the logical volume 200 is reserved by one interface, the other interface does not show the reserved state, and the other interface does not show a forced release command (Bus Device R).
reset or UNCON RSV) can be prevented from affecting the reserved state.

Also, depending on the type of data in the logical volume 200 and its position in the system, different interfaces may be made equal to each other or one interface may be superior to the other interface with respect to the logical volume 200. It can also be. That is, in the reserve / release function, the first input / output interface 310
Reserve has priority over the reserve of the second input / output interface 410 and has the effect of forced release, forced reserve, or reset. However, the reserve, forced reserve, forced release, and reset of the second input / output interface 410 are the second. It may be unequal to have an effect only within the range of the input / output interface 410. The reverse is also possible.

Further, under the control of the same disk controller,
The logical volumes 200 having the attributes of the first and second input / output interfaces 310 and 410 having the same priority can be placed in any combination.

(Embodiment 3) FIG. 18 is a block diagram showing an example of an information processing system according to another embodiment of the present invention.

In the information processing system according to the third embodiment, the logical volume 200 is constituted by a plurality of sections 250. Such a section 250 can be exemplified by a case where a plurality of small disk devices are connected to form a logical volume 200 virtually. The other configuration is almost the same as that of the first embodiment, and the description is omitted.

In such an information processing system, when different interfaces are accessing, it is not necessary to occupy the entire logical volume 200 as described in the first and second embodiments, and one area 250 can be occupied. Is enough.

The method for exclusively controlling the area 250 is shown in FIG.
9 will be described. FIG. 19 is a configuration diagram showing an example of the logical volume management table used in the third embodiment.

In the logical volume management table 500,
Logical volume management block 5 including area data 519
10 inclusive. Also, an interface busy flag 511
Can be provided for each area data 519 in the logical volume management block 510.

According to the information processing system and the information input / output control method of the third embodiment, since exclusive control of the interface is performed for each area 250, the same logical volume 20 is used.
If there is an unused area 250 in 0, such unused area can be released to another interface. As a result, the probability of being restricted by another interface when accessing from a plurality of interfaces can be reduced, and the response of the magnetic disk device can be improved.

Although the invention made by the inventor has been specifically described based on the embodiments of the present invention, the present invention is not limited to the above embodiments, and various modifications may be made without departing from the gist of the invention. Needless to say, it can be changed.

For example, in the first to third embodiments, the case where exclusive control is performed for both data recording and reproduction is illustrated. However, exclusive control is performed only for data recording, and data is exclusively controlled. In the case of reproduction, it is also possible not to control exclusively.

[0072]

The main effects obtained by the present invention are as follows.

(1) Data can be quickly and easily shared between a plurality of information processing apparatuses having different input / output interfaces.

(2) Consistency between interface protocols when a plurality of information processing apparatuses try to access the same logical volume or area via different input / output interfaces can be solved.

[Brief description of the drawings]

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

FIG. 2 is a configuration diagram showing a main part of the information processing system of FIG. 1;

FIG. 3 is a configuration diagram showing a main part of the information processing system of FIG. 1;

FIG. 4 is a configuration diagram showing a main part of the information processing system of FIG. 1;

FIG. 5 is a configuration diagram showing a main part of the information processing system of FIG. 1;

FIG. 6 is a flowchart illustrating an example of an information input / output control method used in the information processing system according to the first embodiment;

FIG. 7 is a flowchart illustrating a process of setting an interface busy flag according to the first embodiment;

FIG. 8 is a flowchart illustrating a process of resetting an interface busy flag according to the first embodiment;

FIG. 9 is a state diagram showing how the status of the logical volume is shown to another interface when the logical volume of the first embodiment is being accessed.

FIG. 10 is a conceptual diagram showing an example of a logical volume management block according to the second embodiment.

FIG. 11 is a flowchart illustrating a reserve command process according to the second embodiment.

FIG. 12 is a flowchart illustrating a release process according to the second embodiment.

FIG. 13 is a flowchart for explaining normal command processing according to the second embodiment.

FIG. 14 is a flowchart illustrating a forced release process in a reserved state according to the second embodiment.

FIG. 15 is a state diagram illustrating the handling of a reserve function and a forced release function when a logical volume is shared between a SCSI interface and a channel interface according to the second embodiment.

FIG. 16 is a conceptual diagram showing another example of the logical volume management block according to the second embodiment.

FIG. 17 shows a reserve function when the reserve function of the logical volume is independent of the SCSI interface and the channel interface according to the second embodiment without affecting each other;
FIG. 11 is a state diagram showing handling of a forced release function.

FIG. 18 is a configuration diagram illustrating an example of an information processing system according to a third embodiment.

FIG. 19 is a configuration diagram illustrating an example of a logical volume management table according to the third embodiment.

[Explanation of symbols]

100: Disk control device, 110: First input / output interface control unit, 111, 121: Control program, 1
20: second input / output interface control unit, 130: drive interface unit, 140: common memory, 150 ...
Internal bus, 200: logical volume, 210: path, 2
50 ... area, 300 ... first information processing device, 310 ... first
Input / output interface, 400 second information processing device, 4
10, a second input / output interface, 500, a logical volume management table, 510, a logical volume management block, 511, an interface busy flag, 512, a common reserve flag, 513, 514, a reserve flag,
515: Logical volume management block for the first input / output interface, 516 ... Logical volume management block for the second input / output interface, 519: Area data.

Claims (3)

[Claims] A first information processing device provided with a first input / output interface; and a second information processing device provided with a second input / output interface having a different specification from the first input / output interface. , At least the first and second
A disk controller having an input / output interface of
A disk device placed under the control of the disk controller and including a logical volume consisting of a single area or a logical volume partitioned into a plurality of areas, comprising: An information processing system comprising: a logic for accessing the same area or the same logical volume via the first and second input / output interfaces and sharing data with each other. . 2. The information processing system according to claim 1, wherein, when the first information processing apparatus accesses the area or the logical volume, the second information processing apparatus accesses the area or the logical volume. When attempting to access the logical volume simultaneously, a first logic that places the area or the logical volume under the control of the first or second input / output interface; A second logic for stopping one of them, a third logic for stopping one of the programs of the first or second information processing device, an access of the first information processing device and an access of the second information processing device A fourth logic that serializes the data, an access path between the first information processing device and the first input / output interface, and a second logic that serializes the second information processing device and the second input / output interface. And a fifth logic for disabling an access path between interfaces, or an access path between the first and second information processing devices and the area or the logical volume. An information processing system comprising means for prohibiting simultaneous access of the first information processing apparatus and the second information processing apparatus to the area or the logical volume by executing the following. 3. The information input / output control method for an information processing system according to claim 1, wherein the disk control device stores disk management information corresponding to the area or the logical volume. A first step of referring to the disk management information when a protocol processing or a reserve processing is to be performed on the area or the logical volume from the first input / output interface; By reference, when the area or the logical volume is in an empty state, a protocol process from the first input / output interface to the area or the logical volume or a reserve process to the area or the logical volume is executed. The second step, the disk management information When it is determined by reference that the area or the logical volume is being accessed or reserved by the second input / output interface, the area or the logical volume is notified to the first information processing apparatus. Is busy,
Or a third step of terminating the protocol processing or the reservation processing after reporting that the reservation processing is being performed.