JP3216659B2 - Storage device and information processing system using the same - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a storage device and an information processing system using the same, and more particularly, to a storage device capable of connecting and connecting a plurality of storage devices and treating it as one large-capacity storage device. It relates to an information processing system using this.

With the development of information processing devices, it has become possible to process a large amount of data at high speed, but in order to take advantage of the high speed of the information processing device, data is supplied to the information processing device stably and at high speed. It is necessary to do. For that purpose, a large-capacity and high-speed storage device is indispensable.

[0003]

2. Description of the Related Art Access from an information processing apparatus to a storage device is performed as follows. For example, after explicitly specifying a device ID, a storage address of each storage device is specified, and a control circuit and a connection interface on the information processing device side are selected to access one storage device. An example using this method is a magnetic disk device connected via a channel device. When higher speed is required, an extended storage device, which is a semiconductor storage device directly accessible from the CPU, is used.

[0004]

In some cases, a capacity exceeding the storage capacity mounted on a storage device already connected to the information processing apparatus is required for some reason. In this case, the expansion of the storage device is performed.

[0005] In a storage device such as a magnetic disk device connected via the above-described channel device, the storage capacity of one storage device cannot be increased. Therefore, one of the following methods is adopted.

That is, first, a larger capacity (for example, 2 Gbytes) is used instead of the existing storage device (for example, 1 Gbytes).
Is newly connected to the information processing device, and the same device ID is given. However, in this case, most of the investments made so far for the existing storage device are wasted. That is, in this case, replacement of the storage device should be performed rather than extension.

Second, in addition to the existing storage device, another (physically independent) storage device of the same capacity is connected to the information processing device, and another device ID is given. Will be However, if the capacity of a plurality of storage devices is to be utilized in this way, the number of control units (channel devices and the like) of the information processing device, the number of connectors, and the like will increase, and the amount of information processing device will increase. In addition, in order to perform high-speed access, performance using a channel is insufficient, so that the performance of the CPU cannot be sufficiently exhibited.

In the above-mentioned extended storage device directly accessible from the CPU, the expansion of the storage capacity can be realized relatively easily within the range of the physically mountable storage capacity. Since the physical quantities of the control circuit and the interface unit are significantly increased, the number of connected extended storage devices cannot be easily increased.

SUMMARY OF THE INVENTION It is an object of the present invention to provide a storage device whose storage capacity can be substantially expanded relatively easily. Another object of the present invention is to provide a storage device connectable to one or more other storage devices.

It is still another object of the present invention to provide an information processing system capable of relatively easily expanding the storage capacity of a storage device suitable for high-speed access. Still another object of the present invention is to provide an information processing system including a plurality of storage devices connected and connected.

[0011]

According to the present invention, a plurality of storage devices are connected (serial) connected to each other and treated as one large-capacity storage device. This is based on the inventor's new knowledge that the storage device or the capacity can be easily expanded without increasing the burden. For this purpose, the storage device of the present invention includes means for coupling to another storage device (communication means) and means for making a characteristic response to an access request. So
Access exception signal that was originally returned to the access source
Control by using the for route selection
I have to.

FIG. 1 is a block diagram showing the principle of the present invention, and shows a storage device 100 of the present invention. The coupling unit 1 couples another device (not shown) such as an information processing device or a storage device that issues an access request with the self-storage device 100. The coupling means 1 is provided on the access request source side of the connection. The mounting information holding mechanism 2 holds information indicating the mounting state of the self-storage device 100, receives address information corresponding to the access request from the coupling unit 1, and the storage mechanism 5 mounted on the self-storage device 100 It identifies whether or not it is the target, and sends the result to the route selection means 3 as a route selection instruction signal (for example, an access exception signal). The route selection unit 3 receives the route selection instruction signal, and selects a transmission destination of the signal transmitted through the coupling unit 1 based on the signal. The access control mechanism 4 controls access to the self storage mechanism 5. The storage mechanism 5 is a storage mechanism mounted on the self-storage device 100, and is a part that actually stores data. The coupling unit 6 couples another storage device (not shown) and the self-storage device 100.

[0013]

The storage device 100 can be connected to the information processing device by the coupling means 1. The storage device 100 includes the coupling unit 1
Can be connected to the coupling means 6 of another storage device, and by connecting the coupling means 6 to the coupling means 1 of another storage device, it is possible to connect to another storage device. Therefore,
A plurality of storage devices 100 can be connected and connected.

In the storage device 100, the mounting information holding mechanism 2 determines whether the storage mechanism 5 of the storage device 100 itself is an access target. Based on this, the route selection means 3
Sends an access request to the access control mechanism 4 when the storage mechanism 5 of the self-storage device 100 is an access target, and transmits the access request when the storage mechanism 5 of the self-storage device 100 is not an access target. To another storage device via

The same processing is performed in each of the plurality of storage devices 100 connected and connected. Therefore, the access request issued in the information processing device is sequentially transferred between the plurality of storage devices 100 connected and connected. And
Eventually, the storage device 100 having the storage mechanism 5 to be accessed is reached, where it is used for access.

According to the above description, the plurality of storage devices 100 connected and connected can be treated by the information processing device as one storage device having the same device ID. Expansion of the storage capacity can be achieved by newly connecting and connecting a desired number of storage devices 100. Therefore, it can be expanded relatively easily, and the load on the information processing apparatus can be reduced because no new control circuit or connection interface unit is required.

[0017]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS In FIG. 1, coupling means 1 and 6 comprise a communication mechanism. That is, the coupling means 1 is a receiving mechanism, and the coupling means 6 is a transmitting mechanism. It should be noted that coupling means 1 and 6 are provided so as to enable two-way communication between the information processing device and another storage device.

The mounting information holding mechanism 2 includes a self-storage device 100
It is determined whether or not the storage mechanism 5 of the self-storage device 100 is an access target from the information indicating the mounting state of
Based on this, a route selection instruction signal is formed. here,
The access request includes various control signals and data in addition to an actual access request (including address information). The path selection instruction signal is, for example, an access exception signal. The mounting information holding mechanism 2 includes, for example, a floating memory address register (FMAR) indicating the correspondence between the physical address and the logical address of the storage mechanism 5 and the mounting state.

The route selection means 3 transfers an access request to another storage device using an access exception signal which should be returned to the access source as a drive signal. Therefore, the access exception signal that has been simply returned to the access source in the past is not returned. In a predetermined case, an access exception signal is returned to the access source. When the access exception signal is not generated, the route selection means 3 sends an access request to the access control mechanism 4 to access the storage mechanism 5.

FIG. 2 is a structural diagram of the coupling means 1 and 6.
The coupling means 1 and 6 comprise a communication mechanism as described above, but the coupling means 1 and 6 of this embodiment comprise a communication mechanism for performing optical communication using an optical cable as a medium.

As shown in FIG. 2, the coupling means 1 and 6 are integrally formed to transmit and receive signals. As shown later in FIG. 5, by means of integrally formed coupling means 1 and 6,
Two-way communication can be performed between the storage devices 100 and between the storage devices 100 and the information processing device.

The optical / electrical converter 11 receives an optical signal propagated along an optical cable and converts it into an electric signal. The transmitting side of the optical signal is an information processing device or another storage device.

The communication protocol control unit 12 performs protocol control between the transmission side and the storage device 100 in order to perform communication under a predetermined protocol (communication protocol). Under this protocol control, the communication protocol control unit 1
2 is a decoder 1 for receiving a signal from the optical / electrical converter 11
Send to 3.

The decoder 13 restores the received signal to an appropriate internal signal. The received signal is, for example, an access request, and the internal signal is, for example, an operation code, control information (including an access exception signal), address information, data, and the like.

The communication control unit 14 includes various units (optical / electrical conversion unit 1).
1, communication protocol control unit 12, electric / optical conversion unit 61,
Control associated with the error detected in the communication protocol control unit 62), various errors (ECC, transfer length, response time, etc.)
Control of detection mechanism, communication retry control, error correction control,
The control necessary for communication such as handshake control is performed.

The electrical / optical converter 61 converts the electrical signal obtained from the encoder 63 via the communication protocol controller 62 into an optical signal, and transmits this to an optical cable. The communication protocol control unit 62 performs protocol control between the receiving side and the self-storage device 100 to perform communication under a predetermined protocol. Under this protocol control, the communication protocol control unit 62 sends a transmission signal from the encoder 63 to the electrical / optical conversion unit 61.

The encoder 63 converts the internal signal into a format according to a protocol for performing communication. That is, the affinity between the internal signal and the protocol is provided. The coupling means 1 includes an optical / electrical converter 11, a communication protocol controller 1
2, a decoder 13 and a communication control unit 14. The coupling means 6 includes an electric / optical converter 61, a communication protocol controller 6
2. It comprises an encoder 63 and a communication control unit 14.

FIG. 3 is a configuration diagram of the mounting information holding mechanism 2. The mounting information holding mechanism 2 of the present embodiment includes a floating memory address register (FMAR). The FMAR identifies whether (the storage area allocated to) the storage mechanism 5 provided in the self-storage device 100 has the specified address, and if not, generates an access exception signal. Means.

In FIG. 3, a register 20 holds a start address of a storage area allocated to the self-storage mechanism 5. The register 21 holds the mounted capacity of the storage area. The addition circuit 22 obtains the upper limit address of the storage area allocated to the storage mechanism 5 by adding the contents of the registers 20 and 21. The register 23 holds the upper limit address obtained by the adding circuit 22. Register 2
4 holds the lower limit address. Although the register 24 is omitted in many cases because the register 20 is used as it is,
It is described for convenience in comparison with the register 23.

The register 25 holds the address information supplied from the decoder 13. The access address generation mechanism 26 generates an address to be actually accessed from the address information of the register 25. The comparison circuit 27 compares the generated access address with the upper limit address held in the register 23, and generates an access exception signal when the access address is larger than the upper limit address.
The comparing circuit 28 compares the generated access address with the lower limit address held in the register 24, and generates an access exception signal when the access address is smaller than the lower limit address. The OR circuit 29 calculates the logical sum of the access exception signals of the comparison circuits 27 and 28, and generates an access exception signal when either one detects an access exception condition.

In the case where the storage mechanism 5 is composed of a plurality of segments, it is considered that a set of mechanisms excluding the register 25 and the access address generation mechanism 26 is prepared as many as the number of segments. Good.

FIG. 4 is a block diagram of the route selecting means 3. In FIG. 4, a register 31 holds an access exception signal from a previous storage device connected to the own storage device 100. The preceding access exception signal is included, for example, in the control information of the decoder 13. When the self-storage device 100 is directly connected to the information processing device, an access exception signal is not transmitted, but the same processing is performed when there is an access exception signal.

The register 32 holds the access exception signal sent from the OR circuit 29. This access signal is used for route selection, and in a predetermined case, is sent to a later one of the storage devices connected and connected to the own storage device 100.

The register 33 holds a termination flag. The termination flag is set only in the last stage of the connection among the plurality of storage devices connected in the connection. If the termination flag is set in the register 33, the self-storage device 100 is the termination of the connection. Note that the termination flag may be set in the above-mentioned combining means 6. In this case, the route selecting means 3
Refers to the combining means 6 in advance at the time of route selection to determine whether or not a termination flag has been set.

The determination circuit 34 determines, based on the contents of the register 31, that no access exception has occurred in the preceding storage device. If there is no access exception in the previous stage, the selection circuit 3
8 is closed.

The determination circuit 35 determines, based on the contents of the registers 31 and 32, that there is an access exception in the preceding storage device and that there is no access exception in the own storage device 100. In this case, the selection circuit 38 selects a path to the access control mechanism 4 of the self-storage device 100 and sends an access request thereto. The access request is temporarily stored in the register 37.

The discriminating circuit 36 discriminates that there is an access exception in both the preceding storage device and the self-storage device 100 based on the contents of the registers 31 and 32, and
, It is determined whether or not the termination flag is set. In this case, the selection circuit 38 selects the route to the combining means 6 in each case, but the transmission destination and the transmission content differ depending on the presence or absence of the termination flag.

If there is no termination flag, the coupling means 6 can transmit an access exception in the self-storage device 100 and an access request transmitted from the preceding stage to the storage device at the next stage of the connection connection. Then, the selection circuit 38 operates.

If the termination flag is present, it is the termination of the connection connection, and the selection is made so that the coupling means 6 can transmit the occurrence of the access exception to the information processing device (access source) via the preceding storage device. The circuit 38 operates.

FIG. 5 is a configuration diagram of an information processing system according to the present invention. In this example, the four storage devices 100 (100-1 to 100-4) are connected and connected in series, and the information processing device 200 as an access source is connected to the storage device 100-1 at the start of the connection. You. Information processing device 2
Reference numeral 00 mainly includes a CPU (central processing unit) and a main memory.

Note that the coupling means 1 and 6 are formed integrally, and one storage device 100 has only one coupling means 1 and 6, but in FIG. For clarity of communication, they are shown separately as shown. Note that the solid line indicates the outward route of the two-way communication, and the dotted line indicates the return route of the two-way communication.

One storage device 10 is stored in the information processing device 200.
0-1 are connected and used. Storage device 100-
1 has a certain device ID. When the access request from the information processing device 200 results in an access exception, a response to the access exception signal is returned because the termination flag is set in the storage device 100-1.

When the storage capacity needs to be expanded for some reason, the storage devices 100-2 to 100-4 are connected and connected as shown. Storage device 1 at the end of connection
A termination flag is set in 00-4.

Although the storage capacity is increased, for example, four times by this expansion, the expansion itself is performed by each of the storage devices 100-1 to 100-100.
Since the connection is completed by connecting an optical fiber connector between -4 and -4, it is relatively simple. There is almost no physical burden on the information processing device 200 because no channel device is required and no additional connection interface unit is required. Further, since the plurality of storage devices 100-1 to 100-4 are connected, the storage devices are regarded as substantially one storage device, so that the present storage device groups 100-1 to 100-4 are used. The change of the control information may simply define an increase in the storage capacity.

Now, the information processing apparatus 200 is
It is assumed that an access request has been issued for the storage area mounted in C-3. The access request is sent to the storage device 100-1.
Is input to the combining means 1. The input access request is temporarily held in the register 37, and the address information is sent to the mounting information holding mechanism 2. The mounting information holding mechanism 2 identifies that the storage area mounted on the self-storage device 100-1 is not an access target, and sends an access exception signal to the route selection unit 3. The route selecting unit 3 selects a route to the combining unit 6 based on the access exception signal. Further, since the termination flag is not set, the route selecting means 3
The coupling unit 6 transmits the access request and the access exception signal to the storage device 100-2 at the next stage.

As described above, the access request from the information processing device 200 passes through the storage device 100-1 as it is and is sent to (the coupling means 1 of) the storage device 100-2. Similarly, the access request passes through the storage device 100-2 and is sent to the storage device 100-3.

In the storage device 100-3, the mounting information holding mechanism 2 identifies that the own storage device 100-3 is an access target. The path selection means 3 selects a path to the access control mechanism 4 and transmits an access request signal since the self storage area is to be accessed. The access control mechanism 4 performs the designated access to the storage mechanism 5.
For example, in the case of store access to the storage mechanism, the access control mechanism 4 instructs the start of data transmission via the route selection means 3 and the coupling means 1 and stores the data transmitted via these in the storage mechanism 5. In the case of fetch access, the access control mechanism 4 fetches data from the storage mechanism 5 and transmits the data via the route selecting means 3 and the coupling means 6.

Storage device 1 connected to the end of the connection
The control signal and the data returned from 00-3 are received by the coupling means 6 of the storage device 100-2 and / or 100-1 via the path selection means 3 and the coupling means 1, and are further connected to the access source side of the connection. Is transmitted to another storage device 100-1 connected to the information processing device 200 or the information processing device 200 of the access source (indicated by a dotted line in FIG. 5).

As described above, the information processing device 200 accesses the storage device 100-3. However, the information processing device 200 does not need to be aware that the access target is the storage device 100-3 physically separate from the storage device 100-1, and is similar to the case where the storage device 100-1 is accessed. It is. That is, the expanded storage device 100-
This is the same as accessing 1.

Next, the information processing device 200 is
Assume that an access request is issued for a storage area that is not mounted in any of 0-1 to 100-4. This access request passes through the storage devices 100-1 to 100-3 in the same manner as described above, and the storage device 10 at the end of the connection is connected.
Sent to 0-4. In the storage device 100-4, the termination flag is set, and an access exception signal is generated. Then, the route selecting means 3 responds to return the access exception signal to the information processing device 200.

This response is sent from the coupling means 6 of the storage device 100-4, passes through the storage devices 100-3 through 100-1 along the path shown by the dotted line in FIG.
Reaches 00.

The response allows the information processing apparatus 200 to know the occurrence of the access exception. However, the following means can be employed to detect the access exception at a higher speed.

That is, the mounting information holding mechanism 2 or FMAR
Holds information indicating the mounting state of all the other storage devices connected from the self-storage device to the end direction of the connection connection, and from the information and the access request, the other storage device connected in the end direction. It is determined whether or not is an access target. If the access is not the object of the access, an access exception signal is formed and sent to the information processing apparatus 200 via the route selecting means 3 as a response.

For example, it is assumed that the storage device 100-1 holds mounting information of the storage devices 100-2 to 100-4 in addition to the storage device 100-1. In this case, even if the access request is not transferred to the storage device 100-4, the storage device 10
At 0-1, an access exception can be detected early.

It is not always necessary for the storage device 100-1 to hold the mounting information of the storage devices 100-1 to 100-4. For example, the main storage devices 100-1 and 100-
2 holds only the mounting information about itself,
00-3 can hold the mounting information of the storage devices 100-3 and 100-4.

FIG. 6 shows another configuration of the information processing system according to the present invention. In this example, a plurality of (13) storage devices (100-1 to 100-13) are connected and connected in a tree shape. For this reason, the storage devices 100-1 to 100-1
0-13, or each of the storage devices 100-2, 100-3, etc., connected in a tree shape,
Is provided.

Now, the information processing apparatus 200 is
It is assumed that an access request has been issued for the storage area mounted in -5. This access request passes through the storage device 100-1 and reaches the storage device 100-2 as described above. The storage device 100-2 must be able to correctly select the coupling device 6 connected to the storage device 100-3 from among the plurality of coupling devices 6.

To this end, (the mounting information holding means 2 of) the main storage device 100-2 includes, besides the mounting information of the self storage device 100-2, the storage devices 100-3 and subsequent storage devices 100-3.
3, the mounting information (first mounting information) of 100-5 to 100-8, and the storage device 100-
4, holding the mounting information (second mounting information) of 100-9 to 100-13. The first and second mounting information are separately stored so as to correspond to a tree-type path. Further, for example, in the first mounting information, the storage device 100-
The mounting information of 5 to 100-8 is made continuous (so that the addresses are continuous). Thereby, for example, the first
Can be held by four boundary addresses. Storage devices 100-3, 100-5, 100-1
Similarly, at 0, the mounting information is held.

That is, the main storage device 100-2 has its own storage device.
Device information, first mounting information, and second mounting information.
And can be classified into three cases.
You. And, needless to say, the address
It suffices if it is possible to judge whether or not it is an exception. Thus, the coupling unit 6 on the storage device 100-3 side is selected in the storage device 100-2, and the coupling unit 6 on the storage device 100-5 side is selected in the storage device 100-3. Storage device 10
0-5 accesses its own storage mechanism 5 in accordance with the received access request.

It should be noted that the number of storage devices connected in a tree shape like the storage device 100-10 is not limited to two, but may be three (or more). Storage device 100-
7, 100-8, and 100-11 to 100-13 each hold a termination flag.

[0061]

As described above, according to the present invention,
In a storage device and an information processing system, a storage device is provided with a coupling unit with another storage device and a path selection unit, so that a plurality of storage devices can be connected and connected, so that storage capacity can be relatively easily reduced. extension can be, also, Aku
Since the access exception signal is used for path separation, the load on the information processing apparatus for expansion can be reduced.

[Brief description of the drawings]

FIG. 1 is a principle configuration diagram of the present invention.

FIG. 2 is a configuration diagram of a coupling unit.

FIG. 3 is a configuration diagram of a mounting information holding mechanism.

FIG. 4 is a configuration diagram of a route selection unit.

FIG. 5 is a configuration diagram of an information processing system.

FIG. 6 is a configuration diagram of another information processing system.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Coupling means 2 Mounting information holding mechanism 3 Route selection means 4 Access control mechanism 5 Storage mechanism 6 Coupling means 11 Optical / electrical conversion part 12, 62 Communication protocol control part 13 Decoder 14 Communication control part 61 Electric / optical conversion part 63 Encoder 20 , 21, 23, 24, 25 register 22 addition circuit 26 access address generation mechanism 27, 28 comparison circuit 29 OR circuit 31, 32, 33, 37 register 34, 35, 36 discrimination circuit 38 selection circuit 100 (100-1 to 100 -13) Storage device 200 Information processing device

──────────────────────────────────────────────────続 き Continuation of the front page (56) References JP-A-3-25540 (JP, A) JP-A-62-38962 (JP, A) JP-A-63-170755 (JP, A) JP-A 61-38 255451 (JP, A) (58) Field surveyed (Int. Cl. ⁷ , DB name) G06F 12/06 515

Claims (5)

(57) [Claims] A storage mechanism for storing data therein, an access control mechanism for controlling access to the storage mechanism, and an information processing device or another storage device for issuing an access request. holding a first coupling means for coupling between its own storage device and either a second coupling means for coupling with other storage devices and the own storage apparatus, information showing a mounting state of the information storage device Holding means
If the storage mechanism of the self storage apparatus from the holding information and the access request is determined whether the target or not access, and generating means for generating a routing instruction signal on the basis of this, the self storage device According to the termination flag indicating that it is the termination of the connection connection when connected to another storage device, according to the path selection instruction signal and the termination flag,
The access request is sent to the access control mechanism when the storage mechanism of the self-storage device is an access target, and the access is performed when the termination flag does not exist when the storage mechanism of the self-storage device is not the access target. Sending a request to said another storage device via said second coupling means;
A storage device comprising: a path selection unit that sends the access request to the information processing device or another storage device via the first coupling unit when the termination flag exists. Wherein said holding means includes a storage device according to claim 1, characterized in that it consists of floating memory address register. 3. A plurality of storage devices are connected and connected,
An information processing system in which an information processing device is connected to a storage device that is a starting point of these connection connections, wherein each of the plurality of storage devices is mounted on its own storage device, and a storage mechanism for storing data. An access control mechanism that controls access to the storage mechanism; a first coupling unit that couples one of the information processing device or another storage device that issues an access request to the own storage device; Coupling means for coupling between the storage device and the self-storage device, and holding means for holding information indicating the mounting state of the self-storage device
If the storage mechanism of the self storage apparatus from the holding information and the access request is determined whether the target or not access, and generating means for generating a routing instruction signal on the basis of this, the self storage device According to the termination flag indicating that it is the termination of the connection connection when connected to another storage device, according to the path selection instruction signal and the termination flag,
The access request is sent to the access control mechanism when the storage mechanism of the self-storage device is an access target, and the access is performed when the termination flag does not exist when the storage mechanism of the self-storage device is not the access target. Sending a request to said another storage device via said second coupling means;
An information processing system comprising: a path selecting unit that sends the access request to one of the information processing device and another storage device via the first coupling unit when the termination flag is present. 4. The storage unit according to claim 2, wherein said holding unit indicates a mounting state of all of the other storage devices connected from the own storage device to the end direction of the connection connection via the second connection unit.
The generation means determines whether or not the storage mechanism in all of the other storage devices connected in the terminal direction is an access target from the second information and the access request, Based on this, generates the route selection instruction signal, The route selection means, according to the route selection instruction signal,
If the storage mechanism of the self-storage device is not an access target, a storage mechanism of another storage device connected from the self-storage device to the end direction of the connection connection via the second coupling unit is an access target. And the access request to the other storage device via the second coupling means, and the storage of the other storage device connected from the self-storage device to the end of the connection connection via the second coupling means. 2. The storage device according to claim 1, wherein if the mechanism is not an access target, the access request is sent to one of the information processing device and another storage device via the first coupling unit. 5. The second storage unit according to claim 2, wherein said holding unit indicates a mounting state of all of the other storage devices connected from the self-storage device to the end direction of the connection connection via said second connection unit.
The generation means determines whether or not the storage mechanism in all of the other storage devices connected in the terminal direction is an access target from the second information and the access request, Based on this, generates the route selection instruction signal, The route selection means, according to the route selection instruction signal,
If the storage mechanism of the self-storage device is not an access target, a storage mechanism of another storage device connected from the self-storage device to the end direction of the connection connection via the second coupling unit is an access target. And the access request to the other storage device via the second coupling means, and the storage of the other storage device connected from the self-storage device to the end of the connection connection via the second coupling means. 4. The information processing system according to claim 3, wherein if the mechanism is not an access target, the access request is sent to one of the information processing device and another storage device via the first coupling unit.