JPH01310460A - Scsi bus monitoring device - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of Industrial Application The present invention is directed to SCSI (small IC) that controls path interfaces connecting computers, external storage devices, etc.
computer systems 1nterfa
ce) C.Regarding the C monitor device.

BACKGROUND OF THE INVENTION FIG. 2 is a block diagram showing the peripheral configuration of a conventional SCSI bus. SCSI devices 100, 200, and 300 are connected to the SCSI path 500.

SCSI devices 100 and 200 serve as initiators, and SCSI device 300 serves as a target. Furthermore, the SCSI device 300 includes a magnetic disk device 40.
0 is connected.

Next, the operation of the above configuration will be explained with reference to FIG.

When the SCSI device 300 sets the busy (BUSY) signal to "H" level and continues to occupy the SCSI bus 500, the busy signal is monitored by the SCSI device 100 or 200 side. After a certain period of time has elapsed, the busy signal from the SCSI device 300 becomes "H".
If the level is the same, reset condition (R8T) No. 4i (signal 600) is issued from the SCSI device 100, and the SCSI device 300 is released from the SCSI bus 500.

In this way, for devices that continue to occupy the SCSI bus, the deadlock state of the path is released by the reset condition signal.

Problems to be Solved by the Invention However, in the conventional deadlock release method as described above, if the target sets the busy signal to high level and then wakes up, the target will transition to the bus free phase even if it receives the reset condition signal. If this is not possible, there is a problem that the deadlock state of the bus will not be released.

The present invention solves the conventional problems as described above.
S that made it possible to release SCSI path deadlock
The purpose of this invention is to provide a CSI bus monitor device.

Means for Solving the Problems In order to achieve the above object, the present invention includes an input port monitoring control unit that monitors changes in the state of a busy signal output from a SCSI device, and a bus control unit that is connected to the input port monitoring control unit and The timer control section that determines the activation timing for resetting the signal generates a reset signal in conjunction with the count-up of the timer in the timer control section 2 and 3. The controller is equipped with a control means for sending the received signal to the SCSI bus.

Effects The present invention has the following effects due to the above structure. In other words, when the busy signal of the SCSI device becomes high level and continues for a certain period of time, the SCSI device
By detecting an abnormality in the device and suppressing the busy signal of the SCSI device based on this detection, other SCSI
8 SC buses can be released for I-devices.

EXAMPLES Hereinafter, examples of the present invention will be described with reference to the drawings. FIG. 1 is a block diagram of a SCSI bus monitor device in one embodiment of the present invention.

1 is an input port section, which is composed of an 8-bit register. Reference numeral 2 denotes an input port monitoring control unit connected to the input port unit 1 to monitor its status; 3 starts a timer in response to a set notification signal from the input port monitoring control unit 2, and clears the timer value to zero in response to a reset notification signal. This is the timer control section.

4 is a BUSY signal reset control unit that generates two systems of reset signals in response to a reset notification signal from the input port monitoring control unit 2; 10 and 20 are SCSI devices; 12
and 22 are the BUSY signals output from each of the SCSI devices 1.0.20 and the BUSY signal reset control unit 4.
AND(
and) gate. Further, 30 is a SCSI bus, and 13 and 23 are SC:SI devices 10, 2.
This is an inverter inserted between the 0 BUSY signal lines 11 and 21 and the input port section 1.

Next, the operation of the above configuration will be explained.

When a change occurs in the port of input port section 1 (at least 1
When the bit changes from an OFF state to an ON state or vice versa), the input port monitoring control section 2 detects this change. Here, the ON state refers to a state in which the BUSY signal is active, and the opposite is defined as an OFF state.

The input port monitoring control unit 2 sets or resets the timer of the timer control unit 3 depending on the monitoring content. Specifically, a timer set notification signal S for setting a timer when the input port section 1 changes to the ON state.
1 is transmitted to the timer control section 3, and when the timer control section 3 changes to the OFF state, a timer reset notification signal is transmitted from the timer control section 3 to the input port monitoring control section 2.

The timer control unit 3 starts the timer in response to the timer set notification signal Sl from the input port monitoring control unit 2, and if the timer is activated due to reset, stops the timer in response to the timer reset notification signal S2, and clears the timer value to zero. Counts up the timer until a certain amount of time has elapsed since the timer was started. If the timer reset notification signal S2 is not issued from the input port monitoring control unit 2 within this timer period, the timer control unit 3 considers it to be a timeout and sends a timeout notification signal S3 to the input port monitoring control unit 2. Upon receiving the timeout notification signal, the input boat monitoring control unit 2 recognizes that the SCSI bus 30 is in a deadlock state. Based on this, the input port monitoring control section 2 sends a reset notification signal S4 to the BUSY signal reset control section 4. Upon receiving the reset notification signal S4, the BUSY signal reset control section 4 supplies reset signals Ss and Ss to one input terminal of the υ■ gates 12 and 22.

, static gates 12 and 22 receive a reset signal Ss.

S6 and the BUSY signals of SCSI devices 10 and 20]1゜21 are ANDed and SCSI device 1
SCS sends an instruction signal to suppress the BUSY signals of 0 and 20.
Send to I bus 30. Reset signal S5. S6 is low level (0″) and SCSI devices 10, 20
High level (“1”) BUSY output from each
The logical product of the signals 11 and 21 is the gate 12 and 22.
The low level output signal is taken from the SCSI bus 30.
The deadlock state of the SCSI bus 30 is released when the signal is output.

Effects of the Invention As described above, according to the present invention, the 5C3I device (5C3I device) includes an input port monitoring control unit that monitors changes in the state of the busy signal output from the chair, and a A timer control section that determines the reset activation timing for resetting the signal, generates a reset signal in conjunction with the count up of the timer of this timer control section, and performs a logical product of this reset signal and the above-mentioned busy signal. Since a control means for sending signals to the SCSI bus is provided, it is possible to release the deadlock state of the 5C3I devices, guarantee the right to use the 5C3I bus to all 5C3I devices, and control the 5C3I bus. High reliability can be achieved.

[Brief explanation of the drawing]

Fig. 1 is a block diagram of a SCSI bus monitor device according to an embodiment of the present invention, Fig. 2 is a block diagram showing the peripheral configuration of a conventional SCSI bus, and Fig. 3 is an operation of a device connected to a conventional 5C3I bus. FIG. 3 is an operation waveform diagram for explaining. DESCRIPTION OF SYMBOLS 1... Input port section, 2... Input port monitoring control section, 3... Timer control section, 4... BUSY signal reset control section, 10.20... SCSI device,
12.22...AND gate, 13.23...
・Inverter. Name of agent: Patent attorney Toshio Nakao and 1 other person No. 1
figure

Claims (1)

[Claims] an input port monitoring control unit that monitors changes in the state of a busy signal output from the SCSI device; a timer control unit that is connected to the input port monitoring control unit and determines a reset activation timing for resetting the busy signal; A reset signal is generated in conjunction with the count-up of the timer of this timer control section, and a signal obtained by taking the logical product of this reset signal and the above-mentioned busy signal is sent to the SC.
A SCSI bus monitor device comprising: control means for sending data to an SI bus.