JPH04311238A - Input-output interface device - Google Patents

Abstract

PURPOSE:To improve the reliability of a small-sized computer system adopting an SCSI system by doubling the constitution of the input-output interface connected to the computer system. CONSTITUTION:A main controller 3 stops functioning and outputs an ID changing instruction to a sub-controller 4 when an abnormal state which interferes with the access to an input-output device occurs. Upon receiving the ID changing instruction, the sub-controller 4 makes access to an input-output device 5 and controls the data transfer between the device 5 and a host computer 1 in accordance with an access instruction from the host computer 1 by changing the ID code at the time of initialization to ID data which make the access instruction valid.

Description

[Detailed description of the invention]

0001

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an input/output interface device that constitutes an interface of an input/output device used in a computer system.

0002

2. Description of the Related Art Conventionally, computer systems such as personal computers use various input/output devices (I/O devices) such as hard disk drives and printers. Such I/O devices are, for example, SCSI (Small
Computer System Interface
e) is connected to a host computer via a bus.

Each I/O device is controlled by an input/output interface device, which is a controller, and transfers data to and from a host computer. SCSI
In this method, the initiator is, for example, a host computer, and the target is a controller of an I/O device.

By the way, in order to improve the reliability of the device,
Duplex configuration systems are well known. In this method, for example, when one controller becomes inoperable due to an abnormal condition, the control operation of the I/O device is executed by switching to the other controller.

[0005]

In a computer system to which various I/O devices are connected, data transfer between the host computer and the I/O devices must always be performed normally. Therefore, by using the duplex configuration method, each I/O
It is desirable to have a dual controller configuration for the device to improve reliability.

[0006] However, the duplex configuration method is only used for large systems and special equipment;
It is not used in small systems that use the SI method. For this reason, conventionally, special measures have not necessarily been taken to improve the reliability of the interface in small systems.

[0007] An object of the present invention is to realize a duplex configuration of input/output interfaces connected to the system in a small computer system using, for example, the SCSI method, thereby improving the reliability of the system. Its purpose is to provide input/output interface devices.

[0008]

[Means for Solving the Problems] The present invention provides, for example, SCS
This is an input/output interface device in a small computer system using the I method, in which the controller of the input/output device connected to the system has a dual configuration of main controller means and subcontroller means.

The main controller means normally controls data transfer with the host computer by accessing the input/output device in response to an access command from the host computer. The main controller means stops functioning when an abnormal condition occurs and outputs an ID change command to the sub-controller means. The sub-controller means
When an abnormal condition occurs, the input/output device is accessed in place of the main controller means to control data transfer with the host computer.

0010

[Operation] In the present invention, when an abnormal condition that impedes access to the input/output device occurs, the main controller means stops its function and changes the ID to the sub-controller means. Output instructions. In response to receiving the ID change command, the subcontroller means changes the ID code at the initial setting to ID data that makes the access command from the host computer valid, and accesses the input/output device according to the access command to update the host computer. Control data transfer to and from your computer.

[0011]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Examples of the present invention will be described below with reference to the drawings.

FIG. 1 shows a computer system according to the same embodiment, and is a block diagram showing the main parts of the system using, for example, a SCSI interface. This system consists of a host computer 1, a host I/O bus (
It consists of a SCSI bus) 2, a main controller 3, a subcontroller 4, and an I/O device 5.

The host computer 1 executes various data processing and accesses the I/O device 5 as necessary. Here, the host computer 1 functions as an initiator. The main controller 3 and the sub-controller 4 function as targets and constitute a dual-configured controller that controls the I/O device 5.

The I/O device 5 is, for example, a hard disk device, and stores data transferred from the host computer 1 and reads accessed data. I/O
The device 5 is controlled by a main controller 3 or a sub-controller 4. Next, the operation of this embodiment will be explained.

First, basically, the main controller 3
controls the I/O device 5 and transfers data between the I/O device 5 and the host computer 1. Here, as shown in step S1 of FIG. 2, at the time of initial setting, an ID code (hereinafter, main ID
The number "0" is set as "0". It is assumed that this ID code "0" is a valid number for an access instruction (command) from the host computer 1.

When the host computer 1 accesses the I/O device 5 and needs to input/output data, it outputs an access command and a target ID code to the host I/O bus 2 (step S2). YES). At this time, the host computer 1 also outputs its own ID code and selects the main controller 3 with the ID code "0" as the target (step S3).

When the main controller 3 is selected by the host computer 1, it outputs a response signal (Busy signal) to the host I/O bus 2.
Securing the right to use. The main controller 3 executes the access command in response to receiving the access command from the host computer 1, and controls the I/O device 5 (step S4). That is, data transfer between the host computer 1 and the I/O device 5 is executed (step S6).

Specifically, when transferring output data from the host computer 1 to the I/O device 5, the main controller 3 outputs a data request signal (REQ signal). Upon receiving the confirmation signal (ACK signal) from the host computer 1, the main controller 3 takes in the output data from the host computer 1 and sends it to the I/O device 5.
Transfer to.

On the other hand, when the read data from the I/O device 5 is transferred and inputted to the host computer 1, the main controller 3 outputs the REQ signal with the read data from the I/O device 5 set. do. The host computer 1 inputs read data in response to receiving the REQ signal and outputs an ACK signal.

In such basic operations, if the main controller 3 detects an abnormality in the interface with the I/O device 5 (YES in step S5) and there is a problem in controlling the I/O device 5, the sub controller 4
transfer control to

That is, when the main controller 3 detects an abnormality, it functions as an initiator and outputs an ID change command to the sub-controller 4 via the host I/O bus 2 (step S7). The sub-controller 4 functions as a target, and upon receiving the ID change command,
Change your ID code "1" from the initial setting to ID code "0"
” (step S9). Thereby, the sub-controller 4 functions as a target selected by the host computer 1 instead of the main controller 3. That is, the sub-controller 4 controls the I/O device 5 in response to an access command from the host computer 1 (step S11).

After outputting the ID change command, the main controller 3 stops its function as a target (also as an initiator) (step S10). That is, the main controller 3 is logically separated from the host I/O bus 2 and the I/O device 5.

[0023] Here, the main controller 3 is connected to the host I
Detects an abnormality in /O bus 2 (YES in step S8)
, if the ID change command cannot be output, the main controller 3 immediately stops its function as a target (also as an initiator) (step S1 in FIG. 3).
2).

[0024] The host computer 1 has a target I
When the D code "0" is output and the main controller 3 is selected, a response signal from the main controller 3 is awaited. When the waiting time for this response signal times out (YES in step S13), the host computer 1 detects that the main controller 3 is abnormal.

On the other hand, the subcontroller 4 constantly monitors the host I/O bus 2, for example. At this time, when the host computer 1 selects the main controller 3 and detects that the response has timed out, the sub-controller 4 changes its own ID code "1" at the initial setting to the ID code "0". (Step S1
4). Therefore, the sub-controller 4 functions as a target selected by the host computer 1 instead of the main controller 3, and controls the I/O device 5 in response to an access command from the host computer 1.
Steps S15, S16).

In this case, regardless of the host I/O bus 2, even if the main controller 3 stops functioning due to a failure, the sub-controller 4 can be transferred to the main controller 3 through the ID change process described above. Instead, it functions as a target.

In this way, normally, the main controller 3 controls the I/O device 5 in response to an access command from the host computer 1, and executes data transfer between the I/O device 5 and the host computer 1. do. The main controller 3 is initially set with an ID code that is valid for access instructions (commands) from the host computer 1.

For example, if an abnormality occurs in the interface with the I/O device 5 and there is a problem in the control operation of the main controller 3, the main controller 3 functions as an initiator and sends the ID change command as a sub. Output to controller 4. As a result, sub controller 4
changes the ID code to an ID code valid for control operations, and replaces the main controller 3 with the host computer 1.
The I/O device 5 is controlled in response to an access command from the I/O device 5.

Furthermore, even if the main controller 3 is unable to output an ID change command due to an abnormality in the host I/O bus 2, the subcontroller 4 changes the ID code to an ID code that is effective for control operations. However, instead of the main controller 3, the I/O device 5 is controlled.

[0030]

As described in detail above, according to the present invention, in a small computer system using the SCSI method, for example, it is possible to realize a redundant configuration of controllers for each I/O device connected to the system. Can be done. Therefore, even if one controller stops functioning, the other controller can control the I/O device, so data transfer between the host computer and the I/O device can always be performed reliably. As a result, the reliability of the system can be improved.

[Brief explanation of the drawing]

FIG. 1 is a block diagram showing main parts of a computer system according to an embodiment of the present invention.

FIG. 2 is a flowchart for explaining the operation of the embodiment.

FIG. 3 is a flowchart for explaining the operation of the embodiment.

[Explanation of symbols]

1...Host computer, 2...Host I/O bus, 3...
Main controller, 4...Sub controller, 5...I/
O device.

Claims (2)

[Claims] 1. An access command from a host computer is enabled based on an ID code at the time of initial setting, and an input/output device is accessed in accordance with the access command to control data transfer with the host computer, and main controller means that stops the function and outputs an ID change command when an abnormal condition that impedes access to the input/output device occurs; and initial settings in response to reception of the ID change command from the main controller means. sub-controller means for changing an ID code at the time to ID data that makes an access command from the host computer valid, and accessing the input/output device in response to the access command to control data transfer with the host computer. An input/output interface device characterized by comprising: 2. An access command from a host computer is enabled based on an ID code at the time of initial setting, and an input/output device is accessed in accordance with the access command to control data transfer with the host computer, and main controller means that stops functioning when an abnormal condition that impedes access to the input/output device occurs, and a response time of the main controller means to an access command from the host computer times out, and the main controller means When the function stops, the ID code at the initial setting is changed to ID data that enables access commands from the host computer, and the input/output device is accessed in accordance with the access command to exchange data with the host computer. An input/output interface device comprising: subcontroller means for controlling transfer.