JP2002251342A - Network system - Google Patents

Abstract

PROBLEM TO BE SOLVED: To effectively utilize hardware resources by increasing a range of a system configuration. SOLUTION: When a network device 3 is connected to a storage device 4 through a connecting means 13, data transferred to the storage device 4 from an arithmetic device 1 is divided into two by the arithmetic device 1 and transferred to the storage device 4 through network devices 2 and 3. The storage device 4 restores the transferred data and stores the restored transferred data inside the device. Also, when the network device 3 is connected to a storage device 5 through a connecting means 14, data transferred to the storage device 4 from the arithmetic device 1 is divided into two by the arithmetic device 1 and transferred to the storage device 4 through the network device 2. The storage device 4 restores the transferred data and stores the restored, transferred data inside the device. Data transferred to the storage device 5 from the arithmetic device 1 is similarly divided into two by the arithmetic device 1 and transferred to the storage device 5 through the network device 3. The storage device 5 restores the transferred data and stores this data inside the device.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a network system for connecting a computing device and a storage device via a network device.

[0002]

2. Description of the Related Art As a conventional network system, there is a network system in which an arithmetic device (computer device) and a storage device are connected via a network device, and data is transferred from the arithmetic device to the storage device via the network device.

[0003]

However, in the conventional network system as described above, the number of storage devices that can be connected to the network system is:
The upper limit has been set by the number of connection means between the network device and the storage device. For this reason, there are problems as described below.

[0004] The first problem is that the upper limit of the number of storage devices that can be connected to the network system is determined only by the connection means, which limits the achievable system configuration.

[0005] The second problem is that if the number of storage devices connected to the network device is less than the upper limit, there are connection means that are not used, and hardware resources cannot be used effectively. That is.

SUMMARY OF THE INVENTION The present invention has been made in view of the above-mentioned problems of the related art, and has an advantage in that a network that can increase the width of a system configuration and effectively use hardware resources can be provided. The purpose is to provide a system.

[0007]

In order to achieve the above object, the present invention provides an arithmetic device, a plurality of storage devices for storing data transmitted from the arithmetic device, the arithmetic device and the plurality of storage devices. In a network system having a plurality of network devices for connecting to a storage device, the arithmetic device performs a data transfer method based on a connection state between the plurality of network devices and the plurality of storage devices. It is characterized by changing.

The arithmetic unit holds connection information indicating a connection state between the plurality of network devices and the plurality of storage devices, and controls data and a transfer destination of the data based on the connection information. Has an output control circuit for transmitting the control information of each of the plurality of network devices, each of the plurality of network devices,
A transfer destination of the data is controlled based on control information transmitted together with the data from the output control circuit, and the data is transferred to a storage device of the transfer destination.

Further, the output control circuit divides the data and transmits the divided data to each of the plurality of network devices together with the control information based on the connection information. .

[0010] Each of the plurality of storage devices may include:
Holding connection information indicating a connection state between the plurality of network devices and the plurality of storage devices, and dividing the data transferred from the network device by the output control circuit based on the connection information An input control circuit for restoring a previous state is provided.

Further, when the connection state between the plurality of network devices and the plurality of storage devices is changed, the connection information held in the output control circuit and the input control circuit is changed. .

[0012] Further, there is provided an arithmetic device, a plurality of storage devices for storing data transmitted from the arithmetic device, and a plurality of network devices for connecting the arithmetic device and the plurality of storage devices. In the network system, each of the plurality of network devices changes a data transfer method based on a connection state between the plurality of network devices and the plurality of storage devices.

Further, each of the plurality of network devices holds connection information indicating a connection state between the plurality of network devices and the plurality of storage devices, and is transmitted from the arithmetic device based on the connection information. An output control circuit for controlling a transfer destination of the received data and transferring the data to a storage device of the transfer destination.

Further, the output control circuit divides the data, and transfers the divided data to a destination storage device based on the connection information.

[0015] Each of the plurality of storage devices may include:
Holding connection information indicating a connection state between the plurality of network devices and the plurality of storage devices, and dividing the data transferred from the network device by the output control circuit based on the connection information An input control circuit for restoring a previous state is provided.

Further, when the connection state between the plurality of network devices and the plurality of storage devices is changed, the connection information held in the output control circuit and the input control circuit is changed. .

(Operation) In the present invention configured as described above, in the arithmetic device or the network device,
Since the data transfer method is changed based on the connection status between the network device and the storage device, even when the connection between the existing network device and the storage device is changed, the data transfer method is used according to the connection status. Can be performed.

[0018]

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

(First Embodiment) FIG. 1 is a diagram showing a first embodiment of a network system according to the present invention.

As shown in FIG. 1, in the present embodiment, an arithmetic unit 1 having an output control circuit 100 for controlling output data, network devices 2 and 3, an input control circuit 200 for controlling input data, And storage devices 4 and 5 each having the same 201.

The computing device 1 is connected to the network devices 2 and 3 via the connection means 10 and 11, respectively.

The network device 2 is connected to the storage device 4 via the connection means 12, and the network device 3
Is connected to the storage device 4 or the storage device 5 via the connection means 13 or the connection means 14.

Here, the configurations of the output control circuit 100 provided in the arithmetic unit 1 and the input control circuits 200 and 201 provided in the storage devices 4 and 5 will be described. For example, the output control circuit 100 and the input control circuits 200 and 20
1 can be realized by a combination of a register and a selector.

First, the configuration of the output control circuit 100 will be described.

FIG. 2 shows the output control circuit 100 shown in FIG.
FIG. 3 is a block diagram showing an example of the configuration.

As shown in FIG. 2, the output control circuit 100
Mode register 1001 and port 0 output control circuit 11
00 and a port 1 output control circuit 1200.

The mode register 1001 holds connection information indicating a connection state between a network device and a storage device in the present system.

The port 0 output control circuit 1100 includes a control data register 1101, a data register 1102,
And a data selector 1103.

The data register 1102 holds data to be stored in a storage device in the system.

The control data register 1101 holds control information for controlling the data held in the data register 1102. This control information is used for controlling the data transfer destination in the network devices 2 and 3.

The data selector 1103 divides the data held in the data register 1102 into two in time series,
Output the divided data.

The port 0 output control circuit 1100 sends a data selector 110 to the network device 2.
3 and the control data register 11
01 is transmitted via the connection means 10.

The port 1 output control circuit 1200 includes a control data register 1201, a data register 1202,
Data selector 1203, selectors 1204, 120
And 5.

The data register 1202 holds data to be stored in a storage device in the present system.

The control data register 1201 holds control information for controlling the data held in the data register 1202. This control information is used for controlling the data transfer destination in the network devices 2 and 3.

The data selector 1203 divides the data held in the data register 1202 into two in time series,
Output the divided data.

The selector 1204 has the mode register 10
Based on the connection information held in 01, any one of the control information held in the control data registers 1101 and 1201 is selected and output.

The selector 1205 is connected to the mode register 10
Based on the connection information held in 01, one of the lower data of the data register 1102 and the data output from the data selector 1203 is selected and output.

The data output from the selector 1205 and the control information output from the selector 1204 are transmitted from the port 1 output control circuit 1200 to the network device 3 via the connection means 11. .

Next, the configuration of the input control circuits 200 and 201 will be described.

FIG. 3 shows the input control circuit 200 shown in FIG.
FIG. 3 is a block diagram showing an example of the configuration. FIG. 4 is a block diagram showing a configuration example of the input control circuit 201 shown in FIG.

As shown in FIG. 3, the input control circuit 200
It comprises a mode register 2000 and an input control unit 2001.

The mode register 2000 holds connection information indicating a connection state between a network device and a storage device in the present system.

The input control unit 2001 includes a data selector 2
101 and a data register 2102.

The data selector 2101 receives the input data transferred from the network device 2 via the connection means 12 and the input data transferred from the network device 3 via the connection means 13 based on the connection information held in the mode register 2000. One of the input data is selected and output.

The data register 2102 holds data to be transferred from the arithmetic unit 1 via the network devices 2 and 3 and stored in the storage device 4.

Further, as shown in FIG.
Reference numeral 1 denotes an input control unit 220 provided with a data register 2202 that holds data to be transferred from the arithmetic device 1 via the network device 3 and stored in the storage device 5.
1 is provided.

In this embodiment, the connecting means 1
Switching between 3 and 14 can be performed by an external switch or updating of a basic program. However, each time the connection means 13 and 14 are switched, it is necessary to update the connection information held in the mode registers 1001 and 2000.

The operation of the network system configured as described above will be described below with reference to FIGS.

First, the network device 3 is connected to the connection unit 13
The operation in the case where the storage device 4 is connected to the storage device 4 via the. In this case, the arithmetic unit 1 changes the data transfer method so as to transfer data to the storage device 4 via the network devices 2 and 3.

In the output control circuit 100 in the arithmetic unit 1, the data transferred to the storage device 4 is stored in the data register 1102 in the port 0 output control circuit 1100 and the data register 120 in the port 1 output control circuit 1200.
2 is held.

In the port 0 output control circuit 1100, the data held in the data register 1102 is divided in time series into two in the data selector 1103.
First, data of the divided upper byte is output.
The data of the upper byte is stored in the control data register 11.
The control information is transmitted to the network device 2 via the connection means 10 together with the control information held at 01.

In the port 1 output control circuit 1200, the selector 1204 selects the mode register 100
The control information held in the control data register 1101 is selected and output based on the connection information held in 1. On the other hand, in the data selector 1203, the data held in the data register 1202 is divided into two in time series, and first, data of the divided upper byte is output. Next, the selector 1205 selects and outputs the lower byte data held in the data register 1102 based on the connection information held in the mode register 1001. The data for this lower byte is
The information is transmitted to the network device 3 via the connection unit 11 together with the control information output from the selector 1204.

That is, in the arithmetic unit 1, the upper byte data is transmitted from the port 0 output control circuit 1100 to the network device 2, and the lower byte data is transmitted from the port 1 output control circuit 1200 to the network device. 3 is sent. Furthermore, for the network devices 2 and 3, both control data registers 11
01 is transmitted.

In the network device 2, the output destination of the data is controlled based on the control information transmitted together with the data from the port 0 output control circuit 1100 in the arithmetic device 1. The data is transferred to the storage device 4 via the storage device 4.

In the network device 3, the output destination of the data is controlled based on the control information transmitted together with the data from the port 1 output control circuit 1200 in the arithmetic device 1. The data is transferred to the storage device 4 via the storage device 4.

In the input control circuit 200 in the storage device 4, the data transferred from the network device 3 (connection means 13) is selected in the data selector 2101 based on the connection information held in the mode register 2000. Output. Then, the data register 21
In 02, the data transferred from the network device 2 (connection means 12) is held as the upper byte, and the data output from the data selector 2101 is held as the lower byte. The data is restored to the state before the operation was performed. After that, the data held in the data register 2102 is stored inside the storage device 4.

Next, the network device 3 is connected to the connection unit 14.
The operation in the case where the storage device 5 is connected to the storage device 5 via the PC will be described. In this case, the arithmetic device 1 transfers data to the storage device 4 via the network device 2,
The data transfer method is changed so that data is transferred to the storage device 5 via the network device 3.

In the output control circuit 100 in the arithmetic unit 1, data transferred to the storage device 4 via the network device 2 is held in the data register 1102 in the port 0 output control circuit 1100. The data transferred to the storage device 5 through the port 3 is held in the data register 1202 in the port 1 output control circuit 1200.

In the port 0 output control circuit 1100, the data held in the data register 1102 is divided in time series into two in the data selector 1103.
Data of the divided upper byte and lower byte is sequentially output. The data output from the data selector 1103 is transmitted to the network device 2 via the connection means 10 together with the control information held in the control data register 1101. In this case, two cycles are required for data transfer, and the control information transmitted together with the data uses the value of the control data register 1101, so that the same control information is transmitted for two cycles.

In the port 1 output control circuit 1200, the selector 1204 selects the mode register 100
The control information stored in the control data register 1201 is selected and output based on the connection information stored in the control data register 1. On the other hand, in the data selector 1203, the data held in the data register 1202 is divided in time series into two, and the divided upper byte and lower byte data are sequentially output. Next, the selector 1205 selects and outputs the data output from the data selector 1203 based on the connection information held in the mode register 1001. The data output from the selector 1205 is transmitted to the network device 3 via the connection unit 11 together with the control information output from the selector 1204.
Sent to. Also in this case, like the port 0 output control circuit 1100, data transfer requires two cycles.

In the network device 2, the output destination of the data is controlled based on the control information transmitted together with the data from the port 0 output control circuit 1100 in the arithmetic device 1. The data is transferred to the storage device 4 via the storage device 4.

In the network device 3, the output destination of the data is controlled based on the control information transmitted together with the data from the port 1 output control circuit 1200 in the arithmetic device 1. Is transferred to the storage device 5 via

In the input control circuit 200 in the storage device 4, the data transferred from the network device 2 (connection means 12) is calculated by the data selector 2101 based on the connection information held in the mode register 2000. The state before the division is restored in the device 1, and the restored data is held in the data register 2102. After that, the data held in the data register 2102 is stored inside the storage device 4.

In the input control circuit 201 in the storage device 5, the data transferred from the network device 3 (connection means 14) is restored to the state before being divided in the arithmetic device 1 and stored in the data register 2202. Will be retained. After that, the data held in the data register 2202 is stored in the storage device 5.

In the present embodiment, a configuration has been described in which only the network device 3 can be connected to both the storage devices 4 and 5, but in the present invention, the network device 2 is similarly connected to the storage devices 4 and 5. 5 may be connectable to both. In such a configuration, the output control circuit 100 in the arithmetic device 1 has a configuration in which two port 1 output control circuits 1200 shown in FIG. 2 are arranged in parallel.

(Second Embodiment) FIG. 5 is a diagram showing a network system according to a second embodiment of the present invention.

As shown in FIG. 5, in this embodiment, an arithmetic unit 51 having an output control circuit 300 for controlling output data, network devices 52 to 54, and input control circuits 400 to 54 for controlling input data are provided. The first embodiment is different from the first embodiment in that three network devices and three storage devices are provided, respectively.

The arithmetic unit 51 is connected to the network devices 52 to 54 via the connection units 61 to 63, respectively.

The network device 52 is connected to the storage device 55 or the storage device 56 via the connection device 64 or the connection device 65, and the network device 53 is connected to the storage device 56 via the connection device 66. The network device 54 is connected to the connection means 67 or the connection means 68.
Is connected to the storage device 56 or the storage device 57 via the.

Here, the configurations of the output control circuit 300 provided in the arithmetic unit 51 and the input control circuit 401 provided in the storage device 56 will be described. The input control circuits 400, 40 provided in the storage devices 55, 57
2 has the same general configuration as the input control circuit 201 shown in FIG.

First, the configuration of the output control circuit 300 will be described.

FIG. 6 shows the output control circuit 300 shown in FIG.
FIG. 3 is a block diagram showing an example of the configuration.

As shown in FIG. 6, the output control circuit 300
Mode register 3001, port 0 output control circuit 31
00, a port 1 output control circuit 3200, and a port 2 output control circuit 3300.

The mode register 3001 holds connection information indicating a connection state between a network device and a storage device in the present system.

The port 0 output control circuit 3100 includes a control data register 3101, a data register 3102,
And a data selector 3103.

The data register 3102 holds data to be stored in a storage device in the present system.

The control data register 3101 holds control information for controlling the data held in the data register 3102.

The data selector 3103 divides the data held in the data register 3102 into three in time series,
Output the divided data.

The port 0 output control circuit 3100 sends the data selector 31 to the network device 52.
03 and the control data register 3
The control information held in 101 is transmitted via the connection means 61.

The port 1 output control circuit 3200 includes a control data register 3201, a data register 3202,
Data selector 3203 and selectors 3204 and 320
And 5.

The data register 3202 holds data to be stored in a storage device in the present system.

The control data register 3201 holds control information for controlling the data held in the data register 3202.

The data selector 3203 divides the data held in the data register 3202 into three in time series,
Output the divided data.

The selector 3204 is connected to the mode register 30
Based on the connection information held in the control data register 01, any one of the control information held in the control data registers 3101 and 3201 is selected and output.

The selector 3205 is connected to the mode register 30
On the basis of the connection information held in 01, any one of the intermediate data obtained by dividing the data of the data register 3102 into three and the data output from the data selector 3203 is selected and output.

The data output from the selector 3205 and the control information output from the selector 3204 are transmitted from the port 1 output control circuit 3200 to the network device 53 via the connection means 62. .

The port 2 output control circuit 3300 includes a control data register 3301, a data register 3302,
Data selector 3303 and selectors 3304 and 330
And 5.

The data register 3302 holds data to be stored in a storage device in the present system.

The control data register 3301 holds control information for controlling the data held in the data register 3302.

The data selector 3303 divides the data held in the data register 3302 into three in time series,
Output the divided data.

The selector 3304 is connected to the mode register 30
Based on the connection information held in the control data register 01, any one of the control information held in the control data registers 3201 and 3301 is selected and output.

The selector 3305 is connected to the mode register 30
Based on the connection information held in 01, one of lower-order data obtained by dividing data in the data register 3302 into three and data output from the data selector 3303 is selected and output.

The data output from the selector 3305 and the control information output from the selector 3304 are transmitted from the port 2 output control circuit 3300 to the network device 54 via the connection means 63. .

Next, the configuration of the input control circuit 401 will be described.

FIG. 7 shows the input control circuit 401 shown in FIG.
FIG. 3 is a block diagram showing an example of the configuration.

As shown in FIG. 7, the input control circuit 401
It comprises a mode register 4000 and an input control unit 4001.

The mode register 4000 holds connection information indicating the connection state between the network device and the storage device in the system.

The input control unit 4001 has a data selector 4
101, 4102 and a data register 4103.

The data selector 4101 receives the input data transferred from the network device 52 via the connection means 65 based on the connection information held in the mode register 4000, and the input data transferred from the network device 53 to the connection means 6 based on the connection information.
6 to select and output any one of the input data transferred.

The data selector 4102 receives the input data transferred from the network device 53 via the connection means 66 and the connection data from the network device 54 to the connection means 6 based on the connection information held in the mode register 4000.
7 to select and output any one of the input data transferred.

The data register 4103 is provided in the arithmetic unit 51.
, Via the network devices 52 to 54, and holds data to be stored in the storage device 56.

In this embodiment, the connection means 6
4, 65 or the connection means 67, 68, the mode register 3001, 4000
It is necessary to update the connection information held in.

In the network system configured as described above, when all of the network devices 52 to 54 are connected to the storage device 56, the arithmetic unit 51 transmits data to the storage device 56 via the network devices 52 to 54. Therefore, the data transfer method is changed so as to transfer the data. When the network device 52 is connected to the storage device 55 and the network device 54 is connected to the storage device 57, the arithmetic device 51
2 to transfer data to the storage device 55 via the network device 53, transfer data to the storage device 56 via the network device 53, and further transfer data to the storage device 57 via the network device 54. Will change.

For example, when all of the network devices 52 to 54 are connected to the storage device 56,
In the output control circuit 300 in 1, the data is
And the divided data is divided into network devices 5
2 to 54 to the storage device 56,
In the input control circuit 401 in 6, the data divided into three is restored, and the restored data is stored in the storage device 56.

In the present embodiment, a configuration has been described in which the network device 52 can be connected to the storage devices 55 and 56 and the network device 54 can be connected to the storage devices 56 and 57. However, the present invention is not limited thereto. For example, a configuration in which the network device 52 can be connected to only the storage device 55, or a configuration in which the network device 52 is connected to the storage device 5
5 and the network device 54 can be connected to the storage device 55 in addition to the storage devices 56 and 57.

In the first and second embodiments described above, each of the network device and the storage device
Although the configuration in which one or three devices are provided has been described, the present invention is not limited thereto, and a configuration in which four or more network devices and four or more storage devices are provided may be used.

In the first and second embodiments described above, the output control circuit is provided in the arithmetic unit, and the arithmetic unit changes the data transfer method based on the connection state between the network device and the storage device. Although such a configuration has been described, in the present invention, the output control circuit in the arithmetic device is moved into the network device except for some components, and the network device is connected to the network device and the storage device in the connection state. A configuration in which the data transfer method is changed based on this may be used. In such a configuration,
The network device has, for example, a configuration as shown in FIG.

FIG. 8 is a diagram showing a configuration example of a network device used in the network system of the present invention, and shows a network device having an output control circuit. FIG. 8 shows a network device when two network devices and two storage devices are provided in the network system.

As shown in FIG. 8, the network device according to this configuration example includes an output control circuit 1800 including a mode register 1801 and an output control unit 1802.

A mode register 1801 holds connection information indicating a connection state between a network device and a storage device in the present system.

The output control unit 1802 is provided with an arithmetic unit (FIG. 1,
A data register 1803 holding the data transmitted from the data register 1803 and the data held in the data register 1803 are divided into two in time series.
A data selector 1804 transfers the data to a storage device (see FIGS. 1 and 5) based on the connection information held in the mode register 1801.

In the network device configured as described above, the data held in the data register 1803 is divided in time series by the data selector 1804, and the data is divided based on the connection information held in the mode register 1801. The output destination of the output data is controlled,
The data is transferred to the storage device.

[0114]

As described above, in the present invention,
In the arithmetic device, since the data transfer method is changed based on the connection state between the plurality of network devices and the plurality of storage devices, even when the connection between the existing network device and the storage device is changed, the data transfer method is changed. Data transfer can be performed by a transfer method according to the connection state.

Therefore, as a first effect, the network system according to the present invention can be implemented simply by changing the connection between the existing network device and the storage device without increasing the amount of connection means for connecting the network device and the storage device. The effect is obtained that the number of connectable storage devices can be substantially increased.

As a second effect, the number of storage devices that can be connected to the network system with a small modification is small because the amount of hardware required for changing the connection between the existing network device and the storage device is small. Can be substantially increased, whereby the effect that the width of the system configuration can be increased can be obtained.

As a third effect, since the connection between the existing network device and the storage device can be changed using the existing connection means, the hardware resources can be effectively used. The effect is obtained.

Further, as a fourth effect, when the storage device fails, the bandwidth can be increased by changing the connection of the network device, and the degenerate operation using the network device effectively can be performed. The effect that it can be obtained is obtained.

The same effect as described above can be obtained even when the data transfer method is changed based on the connection state between the plurality of network devices and the plurality of storage devices in each of the plurality of network devices. Can be obtained.

[Brief description of the drawings]

FIG. 1 is a diagram showing a first embodiment of a network system according to the present invention.

FIG. 2 is a block diagram illustrating a configuration example of an output control circuit illustrated in FIG. 1;

FIG. 3 is a block diagram showing a configuration example of an input control circuit 200 shown in FIG.

FIG. 4 is a block diagram illustrating a configuration example of an input control circuit 201 illustrated in FIG.

FIG. 5 is a diagram showing a second embodiment of the network system of the present invention.

FIG. 6 is a block diagram illustrating a configuration example of an output control circuit illustrated in FIG. 5;

7 is a block diagram illustrating a configuration example of an input control circuit 401 illustrated in FIG.

FIG. 8 is a diagram showing a configuration example of a network device used in the network system of the present invention.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Operation device 2, 3 Network device 4, 5 Storage device 10-14 Connection means 100 Output control circuit 200, 201 Input control circuit 1001 Mode register 1100 Port 0 output control circuit 1101 Control data register 1102 Data register 1103 Data selector 1200 Port 1 Output control circuit 1201 Control data register 1202 Data register 1203 Data selector 1204, 1205 Selector 2000 Mode register 2001 Input control unit 2101 Data selector 2102 Data register 2201 Input control unit 2202 Data register

Claims (10)

[Claims] An arithmetic device, a plurality of storage devices for storing data transmitted from the arithmetic device, and a plurality of network devices for connecting the arithmetic device and the plurality of storage devices. The network system according to claim 1, wherein the arithmetic unit changes a data transfer method based on a connection state between the plurality of network devices and the plurality of storage devices. 2. The network system according to claim 1, wherein the arithmetic device holds connection information indicating a connection state between the plurality of network devices and the plurality of storage devices, and stores data based on the connection information. And an output control circuit for transmitting control information for controlling a transfer destination of the data to each of the plurality of network devices, wherein each of the plurality of network devices transmits together with data from the output control circuit. A network system, wherein a destination of the data is controlled based on the received control information, and the data is transferred to a storage device of the destination. 3. The network system according to claim 2, wherein the output control circuit divides data, and divides the divided data together with the control information based on the connection information for each of the plurality of network devices. A network system for transmitting to a network. 4. The network system according to claim 3, wherein each of the plurality of storage devices holds connection information indicating a connection state between the plurality of network devices and the plurality of storage devices. A network system, comprising: an input control circuit for restoring data transferred from the network device to a state before being divided by the output control circuit based on the above. 5. The network system according to claim 4, wherein, when a connection state between the plurality of network devices and the plurality of storage devices is changed, the state held in the output control circuit and the input control circuit is changed. A network system for changing connection information. 6. An arithmetic device, a plurality of storage devices for storing data transmitted from the arithmetic device, and a plurality of network devices for connecting the arithmetic device and the plurality of storage devices. The network system according to claim 1, wherein each of the plurality of network devices changes a data transfer method based on a connection state between the plurality of network devices and the plurality of storage devices. 7. The network system according to claim 6, wherein each of the plurality of network devices holds connection information indicating a connection state between the plurality of network devices and the plurality of storage devices. A network system, comprising: an output control circuit that controls a transfer destination of data transmitted from the arithmetic device based on the above, and transfers the data to a storage device of the transfer destination. 8. The network system according to claim 7, wherein the output control circuit divides the data, and transfers the divided data to a destination storage device based on the connection information. And a network system. 9. The network system according to claim 8, wherein each of the plurality of storage devices holds connection information indicating a connection state between the plurality of network devices and the plurality of storage devices. A network system, comprising: an input control circuit for restoring data transferred from the network device to a state before being divided by the output control circuit based on the above. 10. The network system according to claim 9, wherein when a connection state between said plurality of network devices and said plurality of storage devices is changed, said output control circuit and said input control circuit hold said plurality of storage devices. A network system for changing connection information.