JPH05128052A - Data transfer device - Google Patents

Abstract

PURPOSE:To provide a data transfer device capable of preventing the generation of an unnecessary re-connecting request in the opened state of a small computer system interface (SCSI) bus and attaining the effective use of the SCSI bus. CONSTITUTION:Data transfer is time-dividedly executed between initiators 12, 13 and plural targets 14, 15 through the common SCSI bus 11. Each of the targets 14, 15 opens the bus 11 during the inside data processing period and generates a reconnecting request with the bus 11 at the end of its inside data processing. The data transfer device is provided with control means 21, 22 for preventing the generation of reconnecting requests from the targets 14, 15 only for a time based upon commands outputted from the initiators 12, 13 even when the data processing in the targets 14, 15 is ended.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an improvement of a data transfer device for transferring a large amount of digital data between targets via an initiator based on the SCSI (Small Computer System Interface) specifications.

[0002]

2. Description of the Related Art As is well known, according to the SCSI standard, a maximum of eight devices can be connected to a SCSI bus. In a SCSI system in which three or more SCSI devices are connected to the SCSI bus and arbitration is provided, the device that becomes the initiator that acquires the usage right from the bus-free in the arbitration phase becomes the target device in the next selection phase. To decide. In order to effectively use the SCSI bus, the determined target disconnects (releases the bus) when it takes a long time to allow other devices to use the bus, and when the processing ends, the target Reconnection (bus reconnection) is performed from the side.

Here, when the initiator reads a large amount of data from a certain target and processes it and writes the processed data to another target, if the total amount of data is a capacity that can be processed inside the initiator, the data is A series of operations from reading, processing, and writing can be executed regardless of the data transfer capacity (speed) of each target. However, if the total amount of data cannot be processed within the initiator, such as image data, a series of operations to read and write only the amount of data that can be processed should be repeated multiple times. However, at this time, the difference in data transfer rate between the initiator and each target becomes a big problem.

That is, as described above, when a certain amount of data is transferred between the targets on the SCSI bus, each target actually writes the data or prepares the data to be sent next. The time bus is released and the initiator is allowed to perform other processing. Therefore, when the data transfer speed between the initiator and each target is significantly different, the initiator wants to execute processing for one target, but another target with a high processing speed issues a reconnect request, During the generation period, the SCSI bus is occupied by the target having a high processing speed, which causes a problem that the SCSI bus 11 cannot be effectively used.

Specifically, as shown in FIG. 3, the SC
On the SI bus 11, a host computer 12 and another computer 13 as an initiator, an image processing device 14 as a target and an HD (hard disk) device 1
5 is connected, the image data is read from the image processing device 14 by using the host computer 12 as an initiator, subjected to a predetermined process, and written in the HD device 15. In this case, the amount of image data that can be transferred from the image processing device 14 to the host computer 12 at one time is three times the amount of image data that can be transferred from the host computer 12 to the HD device 15 at one time, and the image processing device 14
It is assumed that the target has a higher priority than the HD device 15.

Then, in the period A1 shown in FIG. 4, the image data is transferred from the image processing device 14 to the host computer 12, and the image data is transferred from the host computer 12 to the HD in three times of the periods B1 to B3 shown in FIG. The operation of transferring to the device 15 is repeated. However, during the period B1 to B3 during which the image data is transferred from the host computer 12 to the HD device 15, that is, the HD
During the period in which data is being written inside the device 15, the period shown in FIG. 4 from the image processing device 14 that has already completed the preparation for sending the next image data, even though the SCSI bus 11 is in the open state. A reconnect request is generated at C1 to C7. And during this period C1 to C7,
Since the SCSI bus 11 is occupied by the image processing device 14, the SCSI bus 11 is not effectively used.

At point a in FIG. 4, assuming that the reconnect request is generated in the period C4 and the data transfer from the host computer 12 to the HD device 15 is performed in the period B2 at the same timing, the image processing apparatus is executed. 14 is H
Since the priority of the target is higher than that of the D device 15, the reconnect request is generated first and the host computer 12
Since the data transfer from the HD device to the HD device 15 is delayed,
As a result, there is a disadvantage that efficient data transfer cannot be performed.

[0008]

As described above, in the conventional data transfer device according to the SCSI specification, the SCSI bus is effectively used because unnecessary reconnect requests are repeatedly generated when the SCSI bus is open. You have the problem that you cannot.

Therefore, the present invention has been made in consideration of the above circumstances, and it is possible to prevent an unnecessary reconnect request from being generated in the open state of the SCSI bus and to effectively use the SCSI bus. An object is to provide a data transfer device.

[0010]

A data transfer apparatus according to the present invention transfers data in a time division manner between an initiator and a plurality of targets via a common SCSI bus. It is intended for the one that releases the SCSI bus during the data processing period in (1) and issues a reconnection request with the SCSI bus when the internal data processing is completed. Then, the target is provided with a control means for preventing the reconnection request from being generated for a time based on a command from the initiator even when the internal data processing is completed.

[0011]

According to the above structure, even if the internal data processing of the target is completed, the reconnect request is prevented from being generated for the time based on the command from the initiator. It is possible to prevent an unnecessary reconnection request from being generated, and it is possible to effectively use the SCSI bus.

[0012]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described in detail below with reference to the drawings. FIG. 1 shows the configuration of an image processing apparatus as a target. That is, the image processing apparatus is configured such that the memory card 16 including the semiconductor memory (not shown) in which image data is stored is incorporated into the memory card I.
The image data is read via the / F (interface) circuit 17, subjected to necessary data processing in the data processing unit 18 and the image processing unit 19, and then sent to the SCSI bus 11 via the SCSII / F circuit 20. It is a thing. A reselection register 22 having a reselection timer 21 is connected to the data processing section 18.

This reselection register 22 is based on the timer output of the reselection timer 21,
The time from disconnection to reconnection to the I bus 11 is set. That is, until the time set by the reselection register 22 has elapsed, the image processing apparatus shown in FIG. 1 is controlled so that a reconnect request is not issued to the SCSI bus 11.

Here, it is considered that the image data is read from the image processing apparatus shown in FIG. 1, the host computer 12 is used as an initiator to perform predetermined processing, and the image data is written to the HD apparatus 15. First, the host computer 12 uses the SCS
From the identify message sent to the I-bus 11, the time information necessary for writing data in the HD device 15 that is the destination of the image data is read, and from this time information, the disconnection to the reconnection to the image processing device is performed. Sends time setting data. Then, the image processing apparatus processes this data and obtains the optimal time from disconnection to reconnection from the reselection timer 21 and the reselection register 22, and within this time, the reconnection request is not issued from the image processing apparatus. Like

Therefore, according to the configuration of the above embodiment, the image data is transferred from the image processing apparatus to the host computer 12 in the period A1 shown in FIG. 2, and the image data is transmitted in the periods B1 to B3 shown in FIG. The operation of transferring from the host computer 12 to the HD device 15 is repeated three times, and during the period B1 to B3 during which the image data is transferred from the host computer 12 to the HD device 15.
That is, during the period in which data is being written in the HD device 15, the reconnect request is not issued from the image processing device even if the preparation for sending the next image data is already completed, and the SCSI bus 11 is effectively used. Become so.
The present invention is not limited to the above-described embodiments, and various modifications can be made without departing from the scope of the invention.

[0016]

As described in detail above, according to the present invention,
It is possible to provide an extremely good data transfer device which can prevent an unnecessary reconnect request from being generated in the open state of the SCSI bus and can effectively utilize the SCSI bus.

[Brief description of drawings]

FIG. 1 is a block diagram showing an embodiment of a data transfer device according to the present invention.

FIG. 2 is a diagram shown for explaining the operation of the embodiment.

FIG. 3 is a block configuration diagram showing a conventional SCSI-specific data transfer device.

FIG. 4 is a diagram for explaining a problem of the conventional device.

[Explanation of symbols]

11 ... SCSI bus, 12 ... Host computer, 13
Computer, 14 ... Image processing device, 15 ... HD device, 16 ... Memory card, 17 ... Memory card I / F circuit, 18 ... Data processing unit, 19 ... Image processing unit, 20 ... S
CSI I / F circuit, 21 ... Reselection timer, 22
… Reselection register.

Front Page Continuation (72) Inventor Keiichi Watanabe 3-3-9 Shimbashi, Minato-ku, Tokyo Inside Toshiba Abu E Co., Ltd. (72) Masahiro Hirabayashi 3-3-9 Shimbashi, Minato-ku, Tokyo No. within Toshiba Abu E Co., Ltd.

Claims (1)

[Claims] 1. A data transfer is carried out in a time division manner between an initiator and a plurality of targets via a common SCSI bus, and the target releases the SCSI bus during a data processing period therein. At the same time, in a data transfer device that generates a reconnection request with the SCSI bus in an internal data processing end state, even if the internal data processing is completed, the target may only receive a time based on a command from the initiator. A data transfer device comprising a control means for preventing the reconnection request from being generated.