JPH035862A - Input/output instruction processing system - Google Patents

Abstract

PURPOSE:To avoid the delay of the end of input/output processing by informing a higher order device side of an under-mentioned event so that the higher order device side can deal immediately with it when the execution delay of long time of an input/output instruction arises at time the higher order device can not forecast. CONSTITUTION:When the execution delay of long time of the input/output instruction arises at an input/output device 3 side at time the higher order device can not forecast, the higher order device 1 side is made capable of immediately dealing with it by informing the higher order device 1 side of this event. Accordingly, a computer system to issue the input/output instruction can detect the execution delay of the instruction extending over long time and arising in an input/output control device 2 or the input/output device 3 at the unexpectable point of time, and becomes capable of using another input/output route. Thus, input/output processing response time can be assured of being within the expected value of the computer system.

Description

[Detailed Description of the Invention] [Table of Contents] Overview Industrial Application Fields Conventional Technology Problems to be Solved by the Invention Means for Solving the Problems Actions Embodiments Effects of the Invention [Summary] Input/output commands sent by the host device The I/O control device that causes the I/O device to read/write data reports to the higher-level device when the input-output command cannot be executed within a predetermined time. The purpose of this is to notify the host device of the event when a long I/O command has been waiting for execution, so that the host device can respond immediately. In an input/output control device that causes an input/output device to read or write data based on an output command,
Storage means for storing information set by the input/output device that the input/output device is in a state in which it is impossible to execute an input/output command within a predetermined time; and a storage means for notifying the host device of the state stored by the storage means. A notification means and a mode setting means for permitting or prohibiting the notification operation of the notification means are provided, and when a host device sends an input/output command, the storage contents of the storage means execute the input/output command within a predetermined time. If the mode setting means permits the notification operation of the notification means, the host device is notified that the execution of the input/output command is pending, and the storage contents of the storage means indicate that the input/output command is not executed. If it is indicated that the command cannot be executed within a predetermined time and the mode setting means prohibits the notification operation of the notification means, the input/output command is placed in a waiting state for execution.

[Industrial application field]

The present invention relates to an input/output control device that causes an input/output device to read/write data based on an input/output command sent by a host device, and particularly relates to an input/output control device that makes it impossible to execute the input/output command within a predetermined time. The present invention relates to an input/output command processing method that enables reporting to a higher-level device in such a case.

In recent years, with the increase in performance and capacity of computer systems, peripheral auxiliary storage devices, mainly magnetic disk devices, are required to have increased storage capacity, smaller size, and higher performance. In order to meet these demands, various techniques have been developed to increase the recording density on recording media as much as possible.

For example, attempts have been made to improve magnetic disk drives by increasing the track density on the surface of the recording medium, thereby making it possible to record as much data as possible on a small-diameter recording medium. However, by increasing the trunk density, the track-to-track distance becomes tiny, which requires a high degree of precision in the positioning mechanism for positioning the data head on the destination trunk for reading and writing data. Now I have to make a request.

On the other hand, it is self-evident that high reliability is always required for auxiliary storage devices in computer systems, and by increasing the recording density without reducing reliability,
There is a demand for increasing capacity.

By the way, the head positioning mechanism of a magnetic disk device is
Because of its mechanical structure, it is easily affected by temperature fluctuations due to heat generation of the device itself or changes in ambient temperature, which is the biggest cause of deterioration in positioning accuracy.

The most effective means to eliminate this drawback is to display physical reference information of the recording medium on each recording medium surface, that is,
Servo information is recorded, and the device itself reads the servo information at regular time intervals, calculates the relative positional fluctuation between the data head and the track on which the servo information is recorded on the recording medium surface, and reads the servo information from the servo head. The control information for operating the head positioning mechanism created based on the servo information read by the head positioning mechanism is corrected.

This correction operation of the head positioning mechanism works effectively to ensure head positioning accuracy in high track density magnetic disk drives, but in order to sufficiently absorb temperature fluctuations, correction must be performed at reasonable time intervals. Actions need to be taken. Further, the correction operation must be performed for each recording medium surface of the apparatus, and since -M has a multilayer recording medium surface, the correction operation requires a relatively long time.

When the power is turned on, the correction interval is shortened, and as time passes and the temperature rise becomes more gradual, the correction interval is lengthened. When an input/output instruction is issued from a computer system, the execution of this instruction is forced to wait. As mentioned above, the time required for this correction is long, and there are cases where the computer system cannot wait, and countermeasures are needed for cases where the computer system cannot wait.

[Conventional technology]

In general, in a magnetic disk drive, a servo hand reads servo information written on the servo surface of a recording medium, and the head positioning mechanism is controlled and operated by control information created based on this servo information, and multiple data heads are operated. Position it on the target cylinder.

A magnetic disk drive configured to perform a correction operation of a head positioning mechanism has tracks each recording a plurality of servo information on a plurality of data surfaces on which data is recorded on a recording medium, and controls the head positioning mechanism. During the programming of the processor, according to a preset time interval, the processor positions the data heads on the trunk that recorded the servo information of the data plane, causes each data head to read the servo information, and reads the servo information from the servo information. For each data surface, the amount of variation in the relative position between the data head and the track of the data surface in which servo information followed by the data head is recorded is calculated and stored.

Then, when the data head specified by the host device is positioned on the target track, an offset signal is sent to the head positioning mechanism based on the amount of variation in the relative position that has been stored, thereby canceling out the amount of variation in relative position and making it more accurate. The data head is positioned on the physical track.

Therefore, while the magnetic disk device is executing a correction operation that calculates and stores the amount of change in relative position, it processes input/output commands issued by the host device that instruct normal data retrieval and writing. I can't do that.

For this reason, conventionally, input/output commands sent from a host device while a magnetic disk device is performing a correction operation are placed in a queue waiting for execution within the magnetic disk control device until the correction operation of the magnetic disk device is completed. It is in a state.

Furthermore, the time period required to perform this correction operation depends on the characteristics of the mechanical structure of the magnetic disk drive and is unique to each type of magnetic disk drive, so the correction operation is performed at a timing determined by the magnetic disk drive itself. is actively implemented.

Therefore, a computer system using the magnetic disk device cannot predict the time when an input/output instruction for a correction operation will be placed in a waiting state.

[Problem to be solved by the invention]

As mentioned above, conventionally, an input/output instruction waits for execution at a time that the host device cannot predict. If the execution time overlaps with the execution time, the execution of the input/output command will not be completed within the predetermined time and will appear to be delayed for a relatively long time.Generally, the period of the correction operation is approximately every few minutes or tens of minutes. It is considered that the delay in execution of input/output instructions will not have a significant impact on the computer system. Furthermore, even if an input/output instruction is waiting for execution in the magnetic disk control unit, that instruction will be executed immediately after the correction operation in the magnetic disk unit is completed. In many cases, you don't have to be conscious of ordering.

However, in the case of computer systems that cannot tolerate delays in the execution time of individual input/output commands in order to guarantee a constant response time for online terminals, etc., input/output commands may be waiting for execution at unpredictable times. There is a problem in that what happens is a serious hindrance.

In view of these problems, the present invention has been developed by notifying the host device of the event when the input/output device is waiting for execution of an input/output command for a long time at a time that the host device cannot predict. The purpose is to enable the host device to respond immediately.

[Means to solve the problem]

FIG. 1 is a block diagram illustrating the invention in detail.

The host device 1 sends an input/output command to the host interface control circuit 5 of the input/output control device 2 to select the input/output control device 2 and instruct the selection of the input/output device 3. The control circuit 4 that controls the input/output control device 2 recognizes an instruction from the higher-level device 1 via the higher-level interface control circuit 5, and selects the input-output device 3 via the lower-level interface control circuit 7.

When this selection is completed, the host device 1 sends an input/output command instructing to read or write data. At this time, the control circuit 4 checks the contents of the storage means 10, and if the input/output device 3 does not have an input/output command waiting for execution, starts data transfer.

That is, the control circuit 4 controls the upper interface control circuit 5 and the lower interface control circuit 7, and when writing data, stores the data sent by the upper device 1 in the backup memory 6 via the upper interface control circuit 5.
The data read from the buffer memory 6 is sent to the input/output device 3 via the lower interface control circuit 7, and written to the address specified by the upper device 1 with the input/output command.

Furthermore, when reading data, the data read from the address specified by the input/output command of the input/output device 3 is transferred to the higher-level device 1 via the lower-level interface control circuit 7, buffer memory 6, and higher-level interface control circuit 5. let

As described above, when the input/output device 3 cannot process input/output commands for a long time because it performs a correction operation of the head positioning mechanism, for example, the input/output device 3 is installed in the lower interface control circuit 7. For example, a flag indicating that the input/output command cannot be executed within a predetermined time is set and stored in the storage means 10.

At this time, when an input/output command is sent from the host device 1, the control circuit 4 selects the input/output device 3, or when the selection of the input/output device 3 is completed and a read/write command is received. , the contents stored in this storage means 10 are checked, and if the flag is stored, the upper interface control I circuit 5
It is checked whether the mode setting means 9 provided in the device permits or prohibits the notification operation.

The mode setting means 9 controls the notification means 8 provided in the place where the notification operation is permitted, and notifies the host device 1 that a state in which the turnout command is to be waited for execution has occurred. or,
When the mode setting means 9 prohibits the notification operation, the control circuit 4 does not notify the host device 1 that the input/output command is in a waiting state, and the host device 1 continues to send out Or, if the input/output device 3 completes the correction operation after waiting for execution of the write command and erases the flag in the storage means 10,
This read or write command is executed as described above.

[Effect]

With the above configuration, when the input/output device 3 performs a correction operation of the head positioning mechanism, the storage means 1
Since the flag is set to 0, the control circuit 4 can know whether the input/output device 3 can immediately execute the input/output command based on whether or not this flag is set. Then, the host device 1 or the operator sets a mode in the mode setting means 9 to permit or prohibit the notification operation.
It is possible to instruct the control circuit 4 to report to the host device 1 that it is in a state of waiting for execution of an input/output command using the notification means 8, or to make the control circuit 4 to be in a state of waiting for execution of an input/output command.

Therefore, the host device 1 is the human output control device 2 and the input/output device 3.
When two or more sets of input/output devices 3 are connected and the two input/output devices 3 store the same data, by setting the mode setting means 9 to a mode that permits notification operation, the host device 1
By accessing another input/output device immediately when one input/output device reports that an input/output command is waiting for execution, it is possible to avoid a delay in the completion of input/output processing.

〔Example〕

FIG. 2 is a block diagram illustrating an embodiment of the present invention, and FIG. 3 is a sequence diagram illustrating the operation of FIG.

In FIG. 2, the same symbols as in FIG. 1 indicate the same functions. The host device 1 connects the human output control devices 2 and 11, the input/output side '4111 device 2 connects the input/output device 3, and the input/output control device 11 connects the input/output device 12. The input/output devices 3 and 12 record the same data, and the input/output control device 11 has the same function as the input/output control device 2.

The host device 1 sends an input/output command to the input/output control device 2, and selects the input/output control device 2 and the input/output device 3 in the sequence shown at SEL in FIG. 3(a).

If the input/output device 3 is not in the instruction execution waiting state, when this selection is completed, a read or write instruction is subsequently sent from the host device I in the sequence shown in CMD in FIG. 3(a).

Then, data transfer is performed between the host device 1 and the input/output device 3 in the sequence indicated by DATA in FIG. 3(a),
The input/output control device 2 reports the command execution result to the host device 1 in the sequence shown in STS in FIG. 3(a).

If the input/output device 3 is in a state of waiting for execution of an input/output command, if a mode that prohibits the notification operation is set in the mode setting means, the WAIT shown in FIG. 3(b) As shown in the example, after sending CMD, a long processing wait occurs, and when the instruction execution waiting state of the input/output device 3 is resolved, the DA
Data transfer is performed in the sequence shown in TA, and instruction execution results are reported in the sequence shown in STS.

Furthermore, when the input/output device 3 enters a state of waiting for the execution of an input/output command, if a mode that permits the notification operation is set in the mode setting means, the human output control device 2 performs the process as shown in FIG. 3 (C
) When a read or write command is received in the sequence shown in CMD, the input/output device 3 is sent in the sequence shown in STS.
reports that it is waiting for an input/output instruction, or
Alternatively, in the sequence shown in STS in FIG. 3(d), immediately after the selection of the input/output device 3 is completed, it is reported that the input/output device 3 is in a state of waiting for execution of an input/output command.

When the host device 1 is notified that the input/output device 3 is waiting for execution of an input/output command, it sends the input/output command to the input/output control device 11 and accesses the input/output device 12 .

Note that whether the operation shown in FIG. 3(C) or the operation shown in FIG. 3(d) is performed depends on the agreement between the host device 1 and the input/output control devices 2 and 11. However, there will be no difference in the effects of the present invention.

FIG. 4 is a detailed block diagram of the input/output control devices 2 and 11 of FIG. 2.

The control circuit 4 controls the entire operation such as instruction processing within the input/output control device, and generally takes a program control structure using a processor.

The input/output device 3 is, for example, a magnetic disk device, and is controlled by a processor. Iff, and as described above, when the state shifts to a state where an input/output instruction is waited for execution, such as a correction operation of the head positioning mechanism, the flag setting section 19, which is provided in the lower interface control circuit 7 and which is composed of, for example, a register, Set the flag to .

Then, when the state in which the input/output instruction is waited for execution ends, the flag set in the flag setting section 19 is reset and erased.

The input/output command sent from the host device enters the protocol control unit 17 that executes the data transfer control procedure of the host interface control circuit 5, is extracted by the command reception unit 13, and is sent to the control circuit 4.

When the control circuit 4 recognizes that the input/output control device has been selected based on the address included in the input/output command, the control circuit 4 controls the data transfer unit 18 and the protocol control unit 20 of the lower-level interface control circuit 7 based on the address included in the input/output command. The input/output device 3 is selected through .

Then, it is checked whether a flag is set in the flag setting section 19, and if the flag is not set, it is determined that the input/output device 3 is in a state where it can immediately execute an input/output command, and the status transmitting section 14 is sent. After that, the protocol control unit 17 reports the selection completion to the higher-level device.

Upon completion of the selection of the input/output device 3, a read or write command is sent from the host device and sent to the control circuit 4 via the command receiving section 13. The data transfer unit 18 is instructed to transfer data between the host device and the input/output device 3 via the protocol control unit 17, buffer memory 6, and protocol control unit 20.

However, when receiving an input/output command, if the flag is set in the flag setting section 19, the control circuit 4 selects the input/output device 3. If the notification operation is permitted, the protocol control unit 17 passes through the status transmission unit 14.
sends a notification to the host device that the input/output command is in a waiting state.

Further, if the setting content of the mode setting unit 16 prohibits the notification operation, the control circuit 4 waits for execution of the read or write command input to the command receiving unit 13, and sends the flag setting unit 1 to the flag setting unit 1.
9 is cleared, and when the flag is cleared, the read or write command that has been waiting for execution is sent to the input/output device 3.

Therefore, as described above, data is transferred between the host device and the input/output device 3, and the control circuit 4 reports the execution result of this command to the host device via the status transmitter 14.

Note that the mode setting unit 16 is configured when the host device is the protocol control unit 1.
Make it possible to set permission or prohibition of the notification operation through step 7, or fix the content to allow the notification operation,
When the operator enables access to the mode setting section 6 of the control circuit 4 using a short-circuit plug or the like, the notification operation may be permitted, and when access to the control circuit 4 is blocked, the notification operation may be prohibited.

〔Effect of the invention〕

As explained above, the present invention enables a computer system that issues input/output instructions to detect, at an unpredictable point in time, a long execution wait for an instruction occurring in an input/output control device or an input/output device. , it becomes possible to use another input/output path, and there is an effect that the turn processing response time can be guaranteed to be within the expected value of the computer system.

8 is a notification means, 9 is a mode setting means, 10 is a storage means, 13 is a command receiving section, 14 is a status transmitting section, 15 and 18 are data transfer sections, 16 is a mode setting section, 17.20 is a protocol control section, 19 is a flag setting section.

[Brief explanation of drawings]

Fig. 1 is a block diagram explaining the present invention in detail, Fig. 2 is a block diagram explaining an embodiment of the present invention, and Fig.
417I of the sequence explaining the operation in the figure is a detailed block diagram of the input/output control device. In the figure, ① is a host device, 2 and 11 are input/output control devices, and 3.
12 is an input/output device, 4 is a control circuit, 5 is an upper interface control circuit, 6 is a buffer memory, 7 is a lower interface control circuit,

Claims (1)

[Scope of Claims] In an input/output control device (2) that causes an input/output device (3) to read or write data based on an input/output command sent by a host device (1), the input/output device (3) ) is in a state in which it is impossible to execute the input/output command within a predetermined time. ) is provided, a notification means (8) for notifying the higher-level device (1) of the state stored by the higher-level device (1), and a mode setting means (9) for permitting or prohibiting the notification operation of the notifying means (8); ) sends an input/output command,
The storage contents of the storage means (10) indicate that it is impossible to execute the input/output command within a predetermined time, and the mode setting means (9) allows the notification operation of the notification means (8). If the input/output command is waiting for execution, the higher-level device (1) is notified that the input/output command is waiting for execution, and the storage contents of the storage means (10) indicate that the input/output command cannot be executed within a predetermined time. If the mode setting means (9) prohibits the notification operation of the notification means (8), the input/output command is placed in a waiting state for execution. Instruction processing method.