JPH1027152A - Scsi controller - Google Patents

Abstract

PROBLEM TO BE SOLVED: To reset a hang-up state without exerting any influence on other devices by issuing a small computer system interface(SCSI) reset signal to a device from a sharing controller on hang-up detection. SOLUTION: For hang-up resetting, a host computer 11 issues a hang-up reset command or vendor-unique hang-up reset message on a host SCSI bus 15 to a common device 18. The sharing controller 12 having received it after connecting a host SCSI bus 14 and a device SCSI bus 16 issues a SCSI reset signal to the device 20 to reset the hang-up state. During the connection of the buses, the sharing controller 12 itself performs timer monitoring, and recognizes the hang-up state when the connection is maintained for a certain time and issues the SCSI reset signal to the device 21, thereby resetting the hang-up state.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a sharing control method for a computer system having a shared device accessible from a plurality of computers, and more particularly, to a SCSI (Small Computer Interface).
SCS for sharing devices in a computer system using a computer system interface)
The present invention relates to an I control device.

[0002]

2. Description of the Related Art In a system having a shared SCSI device that can be accessed from a plurality of computers, a host side SCSI bus and a device side SCSI bus are connected to each other in order to control contention for a shared device among a plurality of host computers. A sharing control device that performs connection, disconnection, exclusive control, and the like is connected, and access between the host and the device is performed via the sharing control device.

FIG. 1 is a configuration diagram of a system having a shared SCSI device accessible from two systems. Each of the host computers 10 and 11 can access the device 20 and the device 21 via the sharing control devices 12 and 13. The sharing control device 12 is a SCSI
And the selection, reselection, command, and message are exchanged with the host SCSI bus 14 and the device SCSI bus 16. Also, the host SCS
Connects and disconnects the I bus and the device SCSI bus. The same applies to the sharing control device 13.

In FIG. 1, during access between a host computer 10 and a device 20, for example, the sharing controller 12 connects the host SCSI bus 14 and the device SCSI.
When the access is completed, the sharing controller 12 connects the host SCSI bus 14 and the device SCSI.
The bus 16 is disconnected. When the host computer 11 issues a selection for access to the device 20 when the host SCSI bus 14 and the device SCSI bus 16 are connected, the sharing control device 12 responds to the selection and sends a message, It is common to report a busy status in the status phase after receiving a command or the like.

[0005] In the above system, when a host computer or a device fails during access between the host computer and the device, the host SC between the host computer and the device fails.
The SI bus and the device SCSI bus hang. Therefore, if the host computer is faulty,
Access between the device being accessed by the host computer and another host computer becomes impossible. Further, when the device is out of order, access between the host computer accessing the device and another device becomes impossible.

As means for releasing the above-mentioned state such as hang-up, in SCSI, a SCSI reset using a dedicated reset signal line and a BUS DEVICE
There is a reset of only a specified device by a RESET message.

[0007]

The above-described SCSI reset or reset by the BUS DEVICE RESET message has the following problems.

The above-mentioned hang-up can be released by issuing a SCSI reset by the host computer which has been accessing. However, if the host computer being accessed is out of order, there is a high possibility that the host computer cannot issue a SCSI reset.

[0009] As another method, a host computer different from the host computer which is currently accessing the host computer is a SCSI.
By issuing the reset, the above-mentioned hang-up can be released. However, in this method, if a device other than the device being accessed is in the process of executing a command, that command is also reset.

In addition, a BUS DEVICE RESET is assigned to a shared device device that is being accessed by a host computer different from the host computer that is being accessed.
Even if the message is issued, the sharing control device cannot issue the message to the device because the device SCSI bus is hung up.

An object of the present invention is to provide a shared SC which is connected to each of a plurality of host computers via a first SCSI bus and is accessible from the plurality of host computers.
In a computer system having a SCSI controller connected to an SI device via a second SCSI bus, a communication system between a host computer and a shared SCSI device can be provided without affecting other devices connected in a daisy chain. An object of the present invention is to provide a SCSI control device capable of releasing a hang-up at the time of access.

[0012]

[Means for Solving the Problems]

[0013]

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

FIG. 1 shows a shared SC accessible from the second system.
FIG. 1 is a diagram illustrating a general configuration of a system having an SI device. The host computer 10 and the host computer 11 can access both the device 20 and the device 21 via the sharing control device.

FIG. 2 shows the sharing control device 1 when the host computer 10 accesses the shared device device 18.
2 shows the processing of FIG.

FIG. 7 shows an example of the configuration of the sharing control device. The SCSI control chip 23 has a selection and reselection detection function, and exchanges selection, reselection, commands, and messages according to instructions from the MPU 22. The host SCSI bus and the device SCSI bus are connected and disconnected.

In FIG. 1 and FIG. 2, when the host computer 10 accesses the shared device 18, the host computer 10
Selection is performed on the sharing control device 12 above,
Upon detecting this, the sharing control device 12 sets the device SCS
A selection is made to the device 20 on the I bus 16. The sharing control device 12 connects the SCSI bus 14 and the SCSI bus 16 in response to the selection response from the device 20, and when the access between the host computer 10 and the device 20 is completed, the host SCSI bus 14 and the device SCSI
The I bus 16 is disconnected.

FIG. 3 shows the processing of the sharing control device 12 when the shared device 18 accesses the host computer 10.

1 and 3, when the shared device 18 accesses the host computer 10, the device 20 performs reselection on the device SCSI bus 16 with respect to the shared controller 12, and detects this. The shared control device 12 is connected to the host computer 10.
Therefore, the reselection to the host computer 10 is performed on the host SCSI bus 14. The sharing control device 12 is connected to the host computer 10.
The host SCSI bus 14 and the device SCSI bus 16 are connected in response to a reselection response from the host computer 10, and when the access between the host computer 10 and the device 20 is completed, the host SCSI bus 14 and the device SCSI bus 16 are disconnected.

FIG. 4 shows the processing of the sharing controller 12 when the host computer 11 issues a selection for accessing the device 20 while the host SCSI bus 14 and the device SCSI bus 16 are connected. .

Host SCSI bus 14 and device SCS
When the host computer 11 issues a selection for accessing the device 20 while the I bus 16 is connected, the sharing control device 12 responds to this selection,
Report a busy status in the status phase after receiving a message, command, etc.

Sharing control device 12 and sharing control device 1
3 performs connection, disconnection, and exclusive control of the host-side SCSI bus and the device-side SCSI bus, as well as the host-side SCSI bus.
While the I bus and the device-side SCSI bus are connected, the BUS DEVIC
If an E RESET message is received, issue a SCSI reset to the device.

A hang-up release command unique to the vendor is provided, and the host-side SCSI bus and the device-side S
While the CSI bus is connected, the host SC on the non-connected side
When a vendor-specific hang-up release command is received from the SI bus, a SCSI reset may be issued to the device. Alternatively, instead of the hang-up release command, the host SCS on the non-connected side
It is also possible to issue a vendor-unique hang-up release message from the I bus and issue a SCSI reset to the device when the message is received.

Hereinafter, a BUS DEVICE RESET from a non-hangup system when a hangup occurs during access between the host computer and the shared device.
The hang-up release by issuing a message or a vendor-specific hang-up release command and a vendor-specific hang-up release message will be described in detail.

In FIG. 1, when the host computer 10 and the shared device device 18 access, the sharing control device 12 is selected by the selection from the host computer 10 or the reselection from the device 20.
Are the host SCSI bus 14 and the device SCSI bus 16
Is accessed by connecting. Host S
After connecting the CSI bus 14 and the device SCSI bus 16, the sharing control device 12
Message phase for selection from 1
In the status phase after the command phase, a busy status is reported to the host computer 11. When a BUS DEVICE RESET message or a vendor-unique hang-up release command or a vendor-unique hang-up release message is received, a SCSI reset is issued to the device 20. With the ability to

The host SCSI bus 14 and the device S
If the host computer 10 or the shared device 18 fails while the CSI bus 16 is connected, the host S
The CSI bus 14 and the device SCSI bus 16 hang.

FIG. 5 shows that the host computer 11 uses the shared device 18 as a means for releasing the hang-up.
2 shows the processing of the sharing control device 12 when issuing a hang-up release command or message.

In FIGS. 1 and 5, the host computer 11 sends a BUS signal on the host SCSI bus 15 to the shared device 18 to release the hang-up.
A DEVICE RESET message or a vendor-specific hang-up release command or a vendor-specific hang-up release message is issued. Host S
After connecting the CSI bus 14 and the device SCSI bus 16, the sharing control device 12 receiving the
The hang-up state can be released because a SCSI reset is issued to the CPU.

Next, during the connection between the host-side SCSI bus and the device-side SCSI bus, the sharing control device itself monitors the timer, and if the connection continues for a certain period of time, recognizes the hang-up state, and causes the device to reset the SCSI. Will be described below.

FIG. 6 shows the processing of the sharing control device 12 when the sharing control device itself monitors the timer and issues a SCSI reset to release the hang-up.

In FIG. 1 and FIG. 6, when the host computer 10 and the shared device device 18 make an access, the sharing control device 12 is connected to the host SCSI bus by selection from the host computer 10 or reselection from the device 20. 14 and device SCSI
Access is performed by connecting to the bus 16. After the connection processing of the host SCSI bus 14 and the device SCSI bus 16, the sharing control device 12 starts timer monitoring. Host computer 10 and device 20
When the access to the device has continued for several seconds, the sharing control device 12 recognizes that a hang-up has occurred, and
The hang-up is released by issuing the SI reset.

[0032]

According to the present invention, a shared memory S connected to each of a plurality of host computers via a first SCSI bus and accessible from the plurality of host computers.
In a computing system having a SCSI controller connected to a CSI device via a second SCSI bus,
The SCSI controller issues a SCSI reset to the device in response to an instruction from the non-hangup host or the detection of a hangup of the sharing controller itself.
The hangup can be released without affecting other devices connected in the daisy chain.

[Brief description of the drawings]

FIG. 1 is a diagram showing a general configuration of a system having a shared SCSI device accessible from a secondary system.

FIG. 2 is a diagram illustrating processing of a sharing control device when a host computer accesses a device.

FIG. 3 is a diagram illustrating processing of a sharing control device when a device accesses a host computer.

FIG. 4 is a diagram for explaining processing of the sharing control apparatus with respect to access from another system during host-device connection.

FIG. 5 is a diagram for explaining processing of the sharing control device by a message or command for a hang-up during host-device connection.

FIG. 6 is a diagram for explaining processing of the sharing control device in timer monitoring for a hang-up during host-device connection.

FIG. 7 is a diagram showing a configuration of a sharing control device.

[Explanation of symbols]

10, 11: Host computer, 12, 13: Shared control device, 14, 15: Host SCSI bus, 16, 1
7: Device SCSI bus, 18, 19: Shared device device, 20, 21: Device, 22: MPU in shared control device, 23: SCSI control chip in shared control device.

Claims (4)

[Claims] A first SCS for each of a plurality of computers;
A shared SCSI device connected via an I bus and accessible from the plurality of computers, and a second SCSI device
A SCSI controller connected via a bus, wherein at the time of access between any one of said plurality of computers and said shared SCSI device, said SCSI controller connected to said one of said computers; Means for connecting one SCSI bus and the second SCSI bus for connecting the shared SCSI device, and terminating access between any one of the plurality of computers and the shared SCSI device The first SCSI bus and the shared SCSI for connecting to the one of the computers.
Means for disconnecting the second SCSI bus connecting to a device and a SCSI bus hang-up during access between any one of the plurality of computers and the shared SCSI device; The shared SC issued by a computer different from the one of the plurality of computers
Means for converting a reset message for the SI device into a SCSI reset and issuing the SCSI reset to the second SCSI bus. 2. Each of the plurality of computers and a first SCS
A shared SCSI device connected via an I bus and accessible from the plurality of computers, and a second SCSI device
A SCSI controller connected via a bus, wherein at the time of access between any one of said plurality of computers and said shared SCSI device, said SCSI controller connected to said one of said computers; Means for connecting one SCSI bus and the second SCSI bus for connecting the shared SCSI device, and terminating access between any one of the plurality of computers and the shared SCSI device The first SCSI bus and the shared SCSI for connecting to the one of the computers.
Means for disconnecting the second SCSI bus connecting to a device and a SCSI bus hang-up during access between any one of the plurality of computers and the shared SCSI device; The second SCS resets the SCSI in response to a hang-up release instruction issued by a computer different from the one of the plurality of computers.
SC means for issuing to the I bus
SI controller. 3. The first SCS and each of the plurality of computers.
A shared SCSI device connected via an I bus and accessible from the plurality of computers, and a second SCSI device
A SCSI controller connected via a bus, wherein at the time of access between any one of said plurality of computers and said shared SCSI device, said SCSI controller connected to said one of said computers; Means for connecting one SCSI bus and the second SCSI bus for connecting the shared SCSI device, and terminating access between any one of the plurality of computers and the shared SCSI device The first SCSI bus and the shared SCSI for connecting to the one of the computers.
Means for disconnecting the second SCSI bus connecting to a device, timer monitoring when the first SCSI bus and the first SCSI bus are connected to the second SCSI bus, and a predetermined time Means for determining a hang-up state when the connection state continues, and issuing a SCSI reset to the second SCSI bus. 4. A shared SCSI device accessible from a plurality of computers, said shared SCSI device being connected to each of said plurality of computers via a first SCSI bus.
A SCSI device device having an SI device and a SCSI controller connected via a second SCSI bus, wherein the SCSI controller is a computer that communicates with any one of the plurality of computers and the shared SCSI device. The second SCSI connecting between the first SCSI bus connecting with any one of the computers and the shared SCSI device.
Means for connecting to an SI bus, and the first means for connecting between any one of the plurality of computers and the one of the plurality of computers in response to termination of access between the shared SCSI device and the first computer. Means for disconnecting the SCSI bus and the second SCSI bus connecting between the shared SCSI device, and any one of the plurality of computers and the shared SC
When a SCSI bus hangs up during access to an SI device, a reset message for the shared SCSI device issued from a computer different from the one of the plurality of computers is converted to a SCSI reset. And the second SC
Means for issuing to the SI bus
CSI device.