JPH02144718A - Control system for dual port interface - Google Patents

Abstract

PURPOSE:To prevent the destruction of the write data by using a port control state monitor means to keep one of two ports waiting for execution of its preference selecting function while the other port is writing data. CONSTITUTION:A busy signal is transmitted to an access request given to a disk 8 from a host device 2, and the device 2 instructs the selection of preference. Thus a port 12 sends the preference selecting instructions to a preference selecting circuit 16 and a port control state monitor means 15. The means 15 checks the control state of a port 11 and inhibits the working of the circuit 16 with reception of the preference selecting instruction in case the port 11 is working with a write instruction. At the same time, the means 15 issues a command to an exclusive control circuit 14 to send a busy signal to the device 2. Then the means 15 issues a command to the circuit 16 to switch a switch circuit 7 to connect the disk 8 to the port 12 when the transfer of the write data is through with the port 11. Then the means 15 issues an instruction to the port 12 to send a data transfer grant signal to the device 2 to perform the transfer of data between the disk 2 and the disk 8. Thus the destruction of the write data is prevented.

Description

[Detailed Description of the Invention] [Summary] In a data recording/reproducing device equipped with a dual port interface, while one higher-level device is using the device, another higher-level device has priority in selecting the device. Regarding the dual port interface control method that prevents data from being destroyed when using the selection function, for the purpose of preventing the destruction of inserted data, one host device is connected to one port of the dual port, The other higher-level device is connected to the other port, and during data transfer with one higher-level device, exclusive control is performed to deny access from the other higher-level device, and the other higher-level device is instructed to select a destination. When a data recording/recording device disconnects from one host device, connects to the other host device, and transfers data.
The playback device monitors the control status of both ports, and when one port is writing data to the data recording/playback device and priority selection is instructed to the other port, the data writing of one port is completed. A boat control status monitoring means is provided to wait until the execution of the function of priority selection of the other port, and while one host device is in the process of writing data, access to the data recording/playback device of the other host device is made to wait. When the data writing operation of one higher-level device is completed, the other higher-level device is connected to the data recording/reproducing device.

[Industrial application field]

The present invention relates to a data recording/reproducing device equipped with a dual port interface, and in particular, while a higher-level device is using the data recording/reproducing device via one port, another higher-level device via the other port takes priority. Select the data recording/reproducing device using 2) First selection tRJ3. The present invention relates to a dual port interface control method that prevents data from being destroyed when using a dual port interface.

In recent years, data recording/disk devices, magnetic tape devices, etc.
The wide variety of interfaces on playback devices tend to be double-voted. Then, the host device connects with the data recording/reproducing device through one port and during data transfer,
Some devices are equipped with a priority selection function that allows another higher-level device to preferentially select and connect to the data recording/reproducing device via the other port.

By the way, when this priority selection function is used, the connection between the higher-level device and the data recording/playback device that is currently transferring data through one port is forcibly broken, and the connection between the higher-level device and the data recording/playback device is transferred through the other port. The data recording/reproducing device is connected and data transfer is started, but at this time, it is necessary that the data being transferred by the higher-level device connected via one port is not destroyed.

[Conventional technology]

FIG. 4 is a Pronk diagram illustrating an example of the prior art.

FIG. 4 shows a case where the data recording/reproducing device is a disk device. A host device 1 such as a disk control unit is connected to a port 4 of a disk device 3, and a host device 2 is connected to a port 5 of the disk device 3. The host device 1 is
For example, when data transfer is instructed from a computer, the port 4 is instructed to switch the switching circuit 7, and the disk 8 is connected to the boat 4 side, thereby connecting the disk 8 and transferring data.

Further, when the host device 2 is instructed to transfer data from the computer, it instructs the port 5 to switch the switching circuit 7,
By connecting the disks 8 to the boat 5 side, the disks 8 are combined and data is transferred, but ports 4 and 5 have exclusive control circuits 9 and 10, respectively, and the disks 8 are connected to each other. I'm monitoring it. Therefore, if port 4 is connected to disk 8, exclusive control circuit 1 of port 5
0 sends a busy message in response to an access request to the disk 8 from the host device 2 and refuses connection of the disk 8.

Further, if the port 5 has connected the disk 8 first, the exclusive control circuit 9 of the port 4 sends a busy signal when the host device 1 requests access to the disk 8, and rejects the connection of the disk 8.

Here, for example, when the exclusive control circuit 10 of the port 5 sends a busy signal to the host device 2, and the host device 2 instructs priority selection, the port 5 accepts this instruction to select the first destination. The signal is sent to circuit 6. Upon receiving this destination selection instruction, the priority selection circuit 6 instructs the port 4 to select the host device 1.
sends a busy signal to interrupt data transfer with the host device 1. Then, the switching circuit 7 is switched, and the disk 8
Connect to port 5 side.

Then, a data transfer permission signal is sent from the port 5 to the host device 2, and data transfer between the host device 2 and the disk drive 8 is performed.

The same applies when the exclusive control circuit 9 of the boat 4 sends a busy message to the host device 1 and the host device 1 instructs Φ light selection.

[Problem to be solved by the invention]

As mentioned above, no matter what state one port is in, the conventional priority selection circuit 6 unconditionally switches the switching circuit 7 and transfers the other port to the disk 8 when priority selection is instructed from the other port. I am trying to connect to. Therefore,
When data is being written to the disk 8 through one of the ports, the data writing is interrupted midway, so the data being written ends in an unguaranteed state with no end mark added.

Therefore, when this data is read out, there is a problem in that an error occurs and the data in the process appears as if it has been destroyed.

In view of these problems, the present invention prevents the written data from being destroyed by making the execution of the priority selection function of the other port wait when one port is writing data. The purpose is to prevent.

[Means to solve the problem] The first part is a block diagram of the principle of the present invention.

The host device 1 instructs the port 11 to switch the switching circuit 7, connects the disk 8 to the boat 11 side, connects the disk 8, and transfers data, and the host device 2 instructs the port 12 to By switching the switching circuit 7 and connecting the disk 8 to the port 5 side, the disks 8 are combined and data is transferred. However, ports 11 and 12 have exclusive control circuits 13 and 14, respectively, and mutual Monitors whether disk 8 is connected to the Therefore, when the disk 8 is connected to the boat 11, the exclusive control circuit 14 of the boat 12 sends a busy signal in response to a request for access to the disk 8 from the host device 2, and rejects the connection of the disk 8.

Also, if the boat 12 connects the disk 8 first,
The exclusive control circuit 13 of the port 11 sends out a busy signal when the host device 1 requests access to the disk 8.
Reject connection of disk 8.

At this time, the port control status monitoring means 15 is controlled by the processor and monitors the control status of the ports 11 and 12, and checks whether or not the port 11 is operating in response to a write command from the host device 1 for >22H. , recognizes whether or not the boat 12 is operating in response to a write command from the host device 2.

Here, for example, the exclusive side of boat 12? :fU circuit 14
When the host device 2 sends a busy message to the host device 2 and the host device 2 instructs priority selection, the boat 12 sends this priority selection instruction to the priority selection circuit 16 and the port control state monitoring means stage 15.

Therefore, the boat control state monitoring means 15 checks the control'<If state of the boat 11, and if the port 11 is operating according to a write command, upon receiving this priority selection instruction, the operation of the priority selection circuit 16 is changed to ↑1 萑. At the same time, it instructs the exclusive control circuit 14 to send out a busy signal to the second-order device 2.

Then, the boat control status monitoring means 15 remembers that the upper bag r2 has requested access to the disk 8,
When the write data transfer of the boat 11 is completed, the priority selection circuit 16 is instructed to switch the switching circuit 7 to connect the disk 8 to the boat 12 side, and the boat 12 is instructed to send the command to the host device 2. A data transfer permission signal is sent, and data transfer between the host device 2 and the disk 8 is performed.

Further, when the exclusive control circuit 13 of the port 11 sends a busy signal to the host device 1, and the host device 1 instructs priority selection, the same is true as above, and detailed explanation will be omitted.

(Function) With the above configuration, the port control status monitoring means 15 recognizes the control status of the ports 11 and 12, and when the boat 11 or 12 is operating upon receiving a tongue-in command, the host device Prohibits the execution of the preferential light selection instruction sent by
When data writing is completed, the disk 8 is coupled to the host device that has instructed priority selection, so that the data being written can be prevented from being destroyed.

(Embodiment) FIG. 2 is a block diagram of a circuit showing an embodiment of the present invention.
FIG. 3 is a flowchart illustrating the operation of FIG. 2.

The host device 1 instructs the port 11 to switch the switching circuit 7, connects the disk 8 to the port 11 side, connects the disk 8, and transfers data, and the host device 2 instructs the port 12 to switch the switching circuit 7 and connect the disk 8 to the port 11 side. By switching the switching circuit 7 and connecting the disk 8 to the port 5 side, the disks 8 are combined and data is transferred. However, ports 11 and 12 have exclusive control circuits 13 and 14, respectively, and mutual Monitors whether disk 8 is connected to the

Therefore, if port 11 connects disk 8,
The exclusive control circuit 14 of the port 12 sends out a busy signal in response to an access request from the host device 2, and rejects connection of the disk 8.

Also, if port 12 is connected to disk 8 first,
The exclusive control circuit 13 of the port 11 sends out a busy signal when the host device 1 requests access to the disk 8.
Reject connection of disk 8.

Port control '41. The status monitoring circuit 17 is composed of a processor, memory, etc., and monitors the control status of the ports 11 and 12. As shown in FIG. 3, it is checked whether the port 11 is in the writing operation. That is, it is checked whether it is operating in response to a write command from the host device 1, and if the write operation is in progress, it is stored that the port 11 is occupied, as shown in FIG.

If the port 11 is not in a write operation, the port control status monitoring circuit 17 checks whether the port 12 is in a write operation, as shown in FIG. That is, it is checked whether the port 12 is operating upon receiving a write command from the host device 2, and if the write operation is in progress, it is stored that the port 12 is in the process of writing, as shown in FIG.

If the port 12 is not in the writing operation, the process returns to the step of checking whether the port 11 is in the writing operation shown in FIG.

When it is remembered that the port 12 is recessed, the port control state monitoring circuit 17 checks whether a priority selection instruction has been input to the port 11 or 12, as shown in FIG.

If the priority selection instruction has not been input, it is checked whether the write operation of the port 11 has been completed, as shown in FIG. 3 (3).

If the write operation of baud) 11 is completed, the baud I-control status monitoring circuit 17 will write the baud I-control status monitoring circuit 17 as shown in FIG.
The memory being written by the port 11 is erased in step 2, but if the write operation of the port 11 is not completed, it is checked whether the old write operation of the port 12 is completed, as shown in FIG.

If the write operation of the port 12 has been completed, as shown in FIG. 3, the port control status monitoring circuit 17 erases the memory that the port 12 is currently writing in, which was stored in the step of FIG. The process returns to the step (2) to check whether the port 11 is in the write operation, but if the write operation of the port 12 is not completed, the process returns to the step (2) in FIG. 3, and returns to the routine to check whether the priority selection instruction has been input.

Here, for example, when the exclusive control circuit 13 of the port 11 sends H-G in response to an access request from the host device l,
When the host device 1 instructs priority selection, the port 11 sends this priority selection instruction to the profit destination selection circuit 16 and the port control state monitoring circuit 17.

Also, when the exclusive control circuit 14 of the port 12 sends a busy message in response to an access request from the higher-level device 2, and the higher-level device 2 instructs to select the first priority, the port 12 transmits this priority selection instruction. ■First 'M) J? Circuit 16 and boat system? ff
1L state monitoring circuit 17.

Therefore, when the priority selection instruction is input, the port 1 control state monitoring circuit 17 prohibits the priority selection operation as shown in FIG. 3 [phase]. That is, priority i! The operation of the flow circuit 16 is prohibited. Then, as shown in FIG. 3, it is checked whether priority selection has been instructed to the port 11. That is, it is checked whether a priority selection instruction has been input to the port 11.

When priority selection is instructed to port 11, a busy message is sent from port 11 to host device 1, as shown in FIG.

The port control status monitoring circuit 17 remembers that the host device 2 has requested access to the disk 8, and waits for the data writing operation of the port 12 to be completed, as shown in FIG. 12, the priority selection circuit 16 is instructed to switch the switching circuit 7 to connect the disk 8 to the port 11 side, and then, as shown in FIG. A data transfer permission signal is sent out to perform data transfer between the host device 1 and the disk 8, and the process returns to the routine of checking whether the port 11 in FIG. 3 is in the process of writing.

If priority selection is not instructed to the port 11 in the routine shown in FIG.

The boat control status monitoring circuit 17 remembers that the host device 1 has requested access to the disk 8, and waits for the data write operation of the port 11 to be completed, as shown in FIG. Upon completion of writing to the port 11, the priority selection circuit 16 is instructed to switch the switching circuit 7, connect the disk 8 to the port 12 side, and then
As shown in Figure ■, a data transfer permission signal is sent from the port 12 to the host device 2, and the host device 2 and the disk 8
At the same time, the routine returns to the routine for checking whether the port 11 shown in FIG. 3 is in a write operation.

〔Effect of the invention〕

As explained above, the present invention allows a data recording/reproducing device equipped with an interface with dual ports to perform this write processing while one port is writing data based on a priority selection instruction sent from a host device. By interrupting this, the data written to the data recording/reproducing device is prevented from being destroyed, so the reliability of the data can be guaranteed.

[Brief explanation of the drawing]

FIG. 1 is a principle block diagram of the present invention, FIG. 2 is a block diagram of a circuit showing an embodiment of the present invention, FIG. 3 is a flowchart explaining the operation of FIG. 2, and FIG.
The figure is a block diagram illustrating an example of the prior art. In the figure, 1.2 is the host device, 3 is the disk device, 4.5, 1
1.12 is a port, 6. I6 is a priority selection circuit, 7 is a switching circuit, 8 is a disk, 9, 10.13.14 is an exclusive control circuit, 15 is a port control state monitoring means,

Claims (1)

[Claims] An interface with dual ports (11) and (12) is provided, one higher-level device is connected to one port, and the other higher-level device is connected to the other port. During data transfer, exclusive control is performed to deny access to the other higher-level device, and when priority selection is instructed by the other higher-level device, the exclusive control is invalidated and connection with one of the higher-level devices is immediately performed. In a data recording/reproducing device that connects to the other host device and transfers data, the control status of both ports (11) and (12) is monitored, and one port transfers data to the data recording/reproducing device. When the priority selection is instructed to the other port while controlling the writing of the port, the exclusive control is enabled and the priority selection of the other port is performed until the data write control operation of the one port is completed. A port control status monitoring means (15) is provided to wait for the execution of the function, and while one host device is writing data to the data recording/reproducing device, the data recording/reproducing device of the other host device waits for the execution of the function. A dual port interface control method characterized in that access to the device is made to wait, and when the data writing operation of the one host device is completed, the other host device is coupled to the data recording/reproducing device. .