JP2982910B2 - Disk drive seek control method and apparatus - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to a seek control method and apparatus in an auxiliary storage device of a computer system.

2. Description of the Related Art In recent years, as the operation of a computer main body has been speeded up, there has been a demand for an auxiliary storage device that stores a large amount of data and that is used as a virtual memory to be speeded up.
For this purpose, it is necessary to shorten the access time of the auxiliary storage device, but in order to shorten the access time, it is necessary to perform seek control so as to shorten the seek time.

2. Description of the Related Art In a magnetic disk device or an optical disk device, which is an auxiliary storage device of a conventional computer system, during a seek for moving a head from one cylinder (track) to another cylinder (track), a higher-level device performs another seek. Even if an instruction (command) for reading data is given, the command may not be executed until the seek is completed.

This will be described for the case of a magnetic disk drive. A method generally called a read ahead cache (Read Ahead Cache) is adopted for a magnetic disk device. For example, after transferring read data requested in response to a data read command from a higher-level device such as a host computer to a higher-level device, data continuous with the data is transferred to a cache provided in a controller of the magnetic disk device. The memory is provided with a read ahead cache (Read Ahead Cache) mechanism that performs a prefetch operation. If there is a defect (scratch) on the magnetic disk medium continuing to the area read by the read command during such pre-reading operation, the defective part is replaced, that is, another defective cylinder is replaced. An area is provided in place of the defective part, and when pre-reading continuous data, a seek for moving the head to this alternate area is performed. Such a replacement process is, for example, USP 4,49
8,146. However, this replacement cylinder is generally allocated on the outermost or innermost side of the magnetic disk opposite to the cylinder most frequently used, so that the defective read-ahead area is replaced with the replacement area. Is often a long-distance seek.

When performing such a long-distance seek, the magnetic head is set to move at a high speed in order to shorten the seek time. Therefore, when the moving speed of the magnetic head exceeds a certain speed, the magnetic disk controller cannot receive a command from the host device for the control.

 The reason is as follows.

The long-distance seek is generally controlled such that the moving speed of the magnetic head is the same as the target speed, as shown in F of FIG. That is, the difference between the current cylinder where the magnetic head is located and the target cylinder is determined, and based on this difference, a target speed curve at which the magnetic head moves so that the magnetic head can move in the shortest time is determined. The head movement is controlled while performing the speed control so that the actual speed of the magnetic head becomes the same. This speed control is performed under the control of a microprocessor (MPU) in the magnetic disk controller. The MPU constantly detects the current position of the magnetic head by detecting a tracking cross pulse (a signal obtained when passing the track) to a target position. If the track (cylinder) width is 17.5 [μm] and the maximum speed of the magnetic head is 2 [m / s], the time for the magnetic head to cross the track is 8.75. [Μs], and the track cross pulse must be monitored at intervals shorter than this interval in order to read the track cross pulse.

Thus, in order for the above processing to be performed by the MPU, 7
It is necessary to perform a process for speed control in a cycle around [μs]. Therefore, during the head seek operation, the microprocessor has almost no margin and cannot perform any other work.For example, the next access instruction comes from a higher-level device and fetches it, and the head seek is performed on the way. It is practically difficult to stop. Therefore, conventionally, when there is a portion that has been subjected to the replacement processing during the data pre-reading control, the pre-reading is stopped at this time without performing a seek in this replacement area, and the next arriving command is immediately received.

Hereinafter, problems of the seek method of the magnetic head will be described in detail. FIG. 2 is a flowchart showing a general magnetic head seek method. In the figure, steps 101 to 103 relate to a process of preparing for a seek start, and steps 104 to 108 relate to a process during a seek. Of these steps, steps 104 to 106 relate to the seek acceleration and constant speed periods, and steps 106 to 108 relate to the deceleration period. First, in step 101, a microprocessor in a magnetic disk device (not shown) determines whether a command received from the device is a seek command. If it is determined that the instruction is not a seek instruction, the next requested process is executed. When the seek command is determined in step 101, in step 102, the microprocessor calculates the difference between the current cylinder stored in its own register and the target cylinder received by the host device, and the direction in which the head should move,
The movement amount and seek direction (head movement direction) of the head are determined, and each calculation result is set in its own predetermined register. In step 103, the microprocessor starts a seek operation by instructing a seek control circuit (not shown) of the movement amount and the direction.

In the following step 104, the microprocessor determines whether or not a track cross signal obtained by reading the servo signal on the magnetic disk has occurred below the interval of the track cross signal that would be obtained when the head moved at the maximum speed. Monitor. When the generation of the track cross signal is confirmed in step 104, the microprocessor subtracts -1 from the moving amount set in its register, that is, the number of cylinders up to the target cylinder in step 105. Then, the new movement amount obtained as a result is given to the seek control circuit. Then, in step 106, the microprocessor determines whether the current head position is at the cylinder position where deceleration should be started to stop the head of the target cylinder. That is, in order to stop the head at the target cylinder, it is necessary to reduce the moving speed of the head a few cylinders before the target cylinder. For this reason, the position at which this deceleration is started is determined in advance by a predetermined target speed curve. It has been decided. When it is determined in step 106 that the vehicle has not yet reached the position where deceleration should be started, the process returns to step 104. On the other hand, when it is determined in step 106 that the current head position is at the cylinder position where deceleration starts, the microprocessor issues a deceleration command to the seek control circuit in step 107 to start deceleration.
In the following step 108, it is determined in the same manner as described above whether or not a track cross signal has been generated. If it is determined that a track cross signal has been generated, the number of cylinders up to the target cylinder is subtracted in step. When it is determined in step 110 that the head has reached the target cylinder, that is, when the register has become "0", the seek is terminated, and control (ON TRACK control) relating to the target cylinder is executed.
On the other hand, if the result of determination in step 110 is that it has not arrived at the target cylinder, processing returns to step 108.

FIG. 3A shows the relationship between the moving speed v of the head and the time t. FIG. 3B shows the relationship between the drive current I of the head moving voice coil motor (VCM) and the time t. Third
FIG. 4C shows the relationship between the head moving distance and time. In the figure, corresponds to the processing of steps 101 to 103, corresponds to the processing of steps 104 to 106, corresponds to the processing of step 107, and corresponds to the case where the target cylinder is determined in step 108.

As mentioned above, the moving speed of the head is about 2 [m /
s], the track (cylinder) width is about 17.5 [μm], and the processing time is about 8.75 [μm]. However, since it takes about 7 μm in the calculation processing of the number of track cross signals to the target cylinder, there is no margin in the processing of the MPU, and it is not possible to perform interrupt acceptance processing and the like.

DISCLOSURE OF THE INVENTION An object of the present invention is to provide a seek control method and apparatus for a disk drive which solves the above problems.

More specifically, an object of the present invention is to provide a seek control method and apparatus that improve throughput.

The object is to transfer data in response to a data read request from an external device to an external device, and to perform a prefetch operation of data continuous with the data to a memory in a disk control device without receiving an instruction from the external device. Performing a seek operation for moving a head from a first position where data requested by an external device on a recording medium is present to a second remote position where data to be prefetched is present under the control of a processor (a). (B) setting a limit speed of a head at which the processor can receive a command from an external device during the execution of the step (a); and (C) detecting whether or not a command has been accepted; and in step (c), the command is accepted by the processor. When it is detected that the, first from a first position 2
(D) stopping the seek operation for moving the head to the position of (i).

Further, the object is to transfer data in response to a data read request from an external device to the external device, and to perform a pre-read operation to a memory in the disk control device of data continuous with the data without receiving an instruction from the external device. When doing
First means for performing a seek operation for moving a head from a first position where data requested by an external device on a recording medium is present to a second remote position where data to be prefetched is present under the control of a processor; Second means for setting a limit speed of a head at which the processor can receive a command from an external device during the execution of the seek operation; and the processor receives a command from the external device during the execution of the seek operation. Third means for detecting whether the command has been received by the processor. The third means performs a seek operation for moving the head from the first position to the second position when detecting that the command has been accepted by the processor. This is expressed by a seek control device of a disk device having a fourth means for stopping.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a diagram showing a seek operation of a conventional and a first embodiment of the present invention; FIG. 2 is a flowchart showing control of a conventional seek operation; FIG. 3 is a diagram showing a conventional seek operation. FIG. 4 is a block diagram showing a first embodiment of the present invention; FIG. 5 is a diagram showing the configuration of the encoder and decoder shown in FIG. 4; FIG. 6 is a diagram showing the operation of the configuration of FIG. FIGS. 7 and 8 are flowcharts showing the operation of one embodiment of the present invention shown in FIG. 4; FIG. 9 is a block diagram showing a main part of the second embodiment of the present invention; FIG. 10 is a flowchart showing the operation of the embodiment of the present invention shown in FIG.

BEST MODE FOR CARRYING OUT THE INVENTION A first embodiment of the present invention will be described with reference to FIGS.

In FIG. 4, an apparatus according to an embodiment of the present invention includes a host device 1 and a magnetic disk device 2 controlled by the host device 1.
Having. The magnetic disk device 2 has an interface control circuit 3, a drive controller 4, a head 6, a magnetic disk 7, a head drive motor 9, and a magnetic disk rotation motor 71.

The interface control circuit 3 controls decoding of commands from the higher-level device 1 or data transfer with the higher-level device 1.
Performed by 1. Microprocessor 301 is bus 304
Input port 302, output port 303, ROM 305, buffer memory (cache memory) 5, communication interface
306 can be accessed.

Further, the microprocessor 301 performs various controls by executing a microprogram stored in the ROM 305. For example, when a command from the host device 1 is received by the input port 302, the reception of this command is notified to the microprocessor 301 by an interrupt. Then, the microprocessor 301 accesses the input port 302 and decodes the received command. Further, when the input port 302 receives write data from the host device 1, the microprocessor 301 controls the bus 304 to communicate with the input port 302 and the communication interface 3.
06 is connected, and write data from the host device 1 is transferred to the drive controller 4. On the other hand, the read data transferred from the drive controller 4 is transferred to the host device 1 by the microprocessor 301 connecting the communication interface 306 and the output port. When storing the read data in the buffer memory 5, the microprocessor 301 connects the communication interface 306 and the buffer memory 5 to store the read data in the buffer memory 5.

On the other hand, the drive controller 4 is connected to the interface control circuit 3 and performs servo control and seek control of the head actuator, and the processing is performed by the microprocessor 401. Microprocessor 401
Can access the ROM 402, the RAM 410, the communication interface 403, the servo control circuit 405, and the encoder / decoder 8 by controlling the bus 404.

The ROM 402 stores a microprogram executed by the microprocessor 401.

The RAM 410 is a work area for data processing and stores flags and data required for processing. The RAM 410 stores a flag 411 indicating a head moving direction, a current cylinder address 412, and a difference between a target cylinder address specified by a read command or a write command from the host device 1 and a current cylinder address, that is, a moving amount of the head. A movement amount register 412 and a counter 413 for storing the movement amount moved during the seek control are provided, and are used for the same control as the control described in FIG.

The communication interface 403 communicates commands and data with the interface control circuit 3.

The servo control circuit 405 operates under the control of the microprocessor 401, and sends a moving direction, a moving amount, and a deceleration start signal of the head from the microprocessor 401. In the servo control circuit 405, when the head movement direction and the movement amount are received, the head is moved in the head movement direction corresponding to the movement direction, and the servo control circuit 405 stored in advance so as to have a speed corresponding to the movement amount is obtained. The speed parameter corresponding to the movement amount is output from the ROM 405 '. Then, a value corresponding to this parameter is set in the speed command register 19 as a target speed command.

The encoder / decoder circuit 8 is for recording data on the disk 7, and is composed of, for example, an MFM or 1-7 encoding / decoding circuit.

On the other hand, the output of the servo head is as shown in FIG.
It is input to the position sense circuit 10. The position sensing circuit 10 converts the read signal of the servo head into a position signal, and outputs two-phase position signals POSN and POSQ to the position signal slice circuit 11.

The position signal slicing circuit 11 generates N + Q> 0 and N> Q from the signals POSN and POSQ, and generates an OFTRK (off-track) signal to the position decoder circuit 12 to generate a track crossing pulse. Circuit 13
Respectively.

The position decoder circuit 12 generates signals of the lower two bits PAR2 and PAR1 of the currently located cylinder address based on the signals of N> Q and N + Q> 0. Also, SNN (SNN) which is a known control signal for creating a fine position signal indicating a linear region of the speed signal and the position signal.
elect N Non-invert), SQN (Slect Q Non-invert), S
NI (Select N invert) and SQI (Select N inver)
Create each signal in t). The track crossing pulse generating circuit 13 generates a track crossing pulse TXPL having a pulse width of 5 [μs] generated at the center between cylinders based on the signals PAR2 and PAR1 and the OFTRK signal.

 The waveforms of these signals are shown in FIG.

The TXPL signal is also notified to the microprocessor 401,
In order to perform the seek control described in FIG.
Accordingly, the value of the RAM movement amount register 413 is subtracted (−1) each time the TXPL arrives, and the movement amount counter 414 is subtracted.
Is added (+1). Then, the microprocessor 401 supplies the value obtained by the subtraction to the servo control circuit 405 and outputs the newly created target speed from the ROM 405 'to the speed command register 19 shown in FIG.

By repeating such control, when the current position of the head described in FIG. 2 becomes a position to be decelerated, the microprocessor 410 issues a deceleration command to the servo control circuit 40.
Put out 5 '. In the servo control circuit 405, the target speed is set to zero in the speed command register 19 so that the target speed becomes zero for deceleration instead of the read data from the ROM 405 ',
The servo system starts deceleration.

Further, the microprocessor 401 further subtracts the movement amount register 413 by the TXPL signal, and when the value becomes zero, the communication interface 403, 306 and the microprocessor 30 notify the host device 1 that the movement amount is completed.
1. Notify the seek completion via the output port 303.

And, the microprocessor 401 has the current cylinder 412
Is added to the value after the seek is completed, that is, the value of the movement amount counter 414, and is set as a new current cylinder, and the seek operation is completed.

Further explaining the servo mechanism with reference to FIG. 5, the TXPL signal is input to the actual speed generating circuit 14, and the actual speed of the head 6 is obtained from the gap between the track cross pulses (TXPL signal). From the drive controller 4, ROM4 as described above
The target speed command obtained from 05 'is input to the speed command register 19. The target speed command is one is determined by the data of the ROM 405 'to set an upper limit V _n the moving speed of the head 6 to the speed that can accept a command from the host device 1. That is, as can be accepted at any time commands from the host device 1 during the seek speed than the upper limit V _n of the moving speed of the conventional head to set the slow limit V _n. When the moving speed of the head 6 is reduced, the arrival interval of the TXPL signal is widened, and as a result, a margin is provided in the microprocessor, so that the interrupt processing can be accepted and the seek can be reliably stopped at any time.

A speed deviation is obtained from the two input signals of the target speed 19 and the actual speed, and the PID control circuit 20 performs PID control. The output signal from the PID control circuit 20 is converted into an analog signal by the D / A converter 15, and the analog signal is amplified by the power amplifier 16 and then input to the voice coil motor 17. The voice coil motor 17 drives the actuator 18 based on the amplified current command value, and the actuator 18 moves the head 6.

The interface control circuit 3 shown in FIG. 4 decodes a command from a higher-level device, and if the command is a seek command, instructs the microprocessor 401 of the drive controller 4 to seek through the communication interfaces 306 and 403 as it is. The interface control circuit 3 changes the recording format of data, instructs writing and reading of data, and performs signal processing (level conversion and transfer protocol processing) for data transfer to a higher-level device. The drive control 4 controls the rotation of the magnetic disk 7 (servo control of ON / OFF of rotation) and the movement control of the head 6 described above. Drive control 4
Informs the interface control circuit 3 of the read / write timing and informs the interface control circuit 3 of an abnormality that has occurred during the above control.

Next, the operation of the first embodiment will be described with reference to FIG. FIG. 1 shows the operation of the first embodiment together with the above-described conventional operation (F) from the start of seek to the end of seek.

In FIG. 1, V _n indicates the limit of the moving speed V of the head 6 which can drive controller 4 performs interrupt processing, host device 1 to the end of the seek start
So that it is possible to perform the limit speed V _n, which can accept a command to set the upper limit V _n of the moving speed V of the head 6, any reliable time to stop seek from.

From the start of the seek operation until the moving velocity of V _n are as expected conventionally, the accelerating. When containing the command speed before the V _m to reach the speed of V _n, as shown by A, and stops the head 6. It should be noted that the head 6 in the conventional method
The time difference from when the stop control is performed is indicated by B.

Then, upon reaching a speed of V _n moves the head 6 at a constant rate of V _n. When entering a command at some point during the uniform motion period of V _n, as shown in C, and stops the head 6. It should be noted that a time difference from the time when the stop control of the head 6 is performed by the conventional method is indicated by D.

State when a command from the seek start to seek end did not enter is indicated by E, since conventional and so as to move the head 6 at a slower limit speed V _n than the limit speed V _0, ends from the seek start However, since the moving speed of the head 6 is slower, the gap between the track crossing pulses is widened, and the head speed control performed for each track crossing pulse has a margin.
A command from the host device 1 can be received even during seek control.

Next, the above will be described with reference to FIG. 7 taking a read / write command executed by the drive controller 4 as an example.

In FIG. 7, first, at step 111, it is determined whether or not the command sent from the higher-level device 1 via the interface control circuit 3 is a seek command. It is determined whether the seek command is a read command or a write command. If it is determined in step 112 that this is due to the write command, in step 117, the same head seek control as in the above-described operation is performed, and then data writing is performed.
Return to 111.

On the other hand, if it is determined in step 112 that the read instruction is issued, seek control and data reading are executed in step 113. Then, in step 114, it is determined whether or not the next seek instruction has come. If there is no seek instruction, in step 115, it is determined whether or not there is a free area in the cache memory 5 under the control of the microprocessor 301. If there is, in step 116, cylinder reading of data (each sector) continuous with the data read by the read command or continuous with the pre-read data is executed.

The contents of the cache memory 5 are erased, for example, at the timing of the next write command.

If a seek command arrives at step 114, step 118
It is determined whether the seek instruction is a read instruction or a write instruction. If it is a read instruction, seek and read are executed in step 133, and if it is a write instruction, seek and write are executed in step 117.
In step 116, if there is a replacement sector during the pre-reading control, the head is moved by seek control to position the head in the replacement sector.

Thus enacted the moving velocity V of the head 6 to the interrupt processing can be performed limits the speed V _n in particular the drive controller 4 in prefetch control, when entering commands during a seek interrupts the movement of the head 6 Thus, the command that has arrived immediately can be executed, so that the throughput can be improved. In addition, since read-ahead control can be performed on a sector that has been subjected to replacement processing, seek control can be performed during a read-ahead cache operation after the end of a general seek operation, and therefore, in this case, throughput can be improved. Can be.

In the first embodiment of the present invention described above, it is possible to move the head 6 at a speed that can surely stop the seek, and immediately stop the head 6 when a command occurs during the seek. Then, this command is processed.

On the other hand, the command generated during the seek instructs the change of the target cylinder, and the control of FIG. 8 enables the change of the target cylinder only by changing the target cylinder without immediately stopping the head 6. Can also be performed.

The control shown in FIG. 8 corresponds to the drive control 4 shown in FIG.
Do. If an interrupt occurs during a seek operation in step 116 of FIG. 7, the processing of FIG. 8 is started. At step 121, it is determined whether or not the generated command indicates a change of the target cylinder. That is, it is determined whether the target cylinder during the seek control matches the target cylinder indicated by the arriving command. If they do not match, the head 6 is stopped immediately or processing according to the command is performed after the end of the seek. Meanwhile, step 12
If it is determined in step 1 that the command needs to change the target cylinder, it is determined in step 122 whether the seek direction is the same as the current seek direction from the head movement direction register 411 and the target cylinder of the arriving command. I do. If the result of the determination in step 122 is not coincident with the seek direction, the movement of the head 6 is immediately stopped in step 125. This stop operation sets the value of the displacement cylinder 413 to zero in FIG. 4 and sends a start of deceleration to the servo control circuit 405. Then, a track cross pulse obtained until the head stops is counted, and the cylinder in which the head has stopped is recognized by the movement amount counter 413, and the current cylinder 412 is updated. Then, a new target cylinder is reset, and a seek is newly started. In contrast,
If the result of the determination in step 122 is the same as the seek direction,
In step 123, it is determined whether a seek to the new target cylinder is still in time. That is, it is determined from the current cylinder 412 and the movement amount counter 414 whether the head has passed the new target cylinder. If the result of the determination in step 123 has already passed, proceed to step 125,
The stop operation starts immediately as before. On the other hand, when it is determined that the determination result in step 123 has not passed, a new target cylinder is set in step 124. That is, a new target cylinder is set by changing the value of the displacement cylinder register 413. Then, the seek is continued. In step 123, it is further considered whether or not the head 6 can be stopped on the new target cylinder by starting the deceleration from the present time, and if it cannot be stopped, the process proceeds to step 123.

Next, a second embodiment of the present invention will be described with reference to FIG.

FIG. 9 shows a configuration of a drive controller 4A used in place of the drive control 4 shown in FIG.

The drive controller 4A includes a main microprocessor (MPU) 451 for performing seek control, a sub-microprocessor (MPU) 452, a ROM 453 storing an operation program for the main microprocessor 451, and an operation program for the sub-microprocessor 452. It comprises a stored ROM 456, a RAM 460 and a bus 457 which are accessed from both the main microprocessor 451 and the sub-microprocessor 452, an encoder / decoder circuit 455, and a servo control circuit 454.

Various registers for seek control are provided in the RAM 460 at the same time as the first embodiment, and a seek interrupt flag 464 is newly provided in the second embodiment. This RAM
460 is main processor 451 and sub microprocessor
Both 452 have common access.

Incidentally, in the second embodiment, the communication interface 458 is used.
4 corresponds to the communication interface 403 in FIG. 4, and the servo control circuit 454 and the ROM 454 'correspond to the servo control circuit 4 in FIG.
05 and ROM 405 ', encoder / decoder circuit 45
Reference numeral 5 corresponds to the encoder / decoder circuit 8 in FIG. 2 and the operation is completely the same, so that the description is omitted.

Next, a second embodiment shown in FIG. 9 will be described with reference to FIG.

The embodiment of FIG. 10 is a step performed during seek control performed in step 116 of FIG.

The sub-microprocessor 452 does not normally operate, and starts operating when the main microprocessor 451 detects that the head seek control is being performed in step 116 in FIG.

That is, in step 201, the sub microprocessor 4
52 monitors whether the main microprocessor 451 is performing seek control during prefetch control. Then, when the main microprocessor 451 starts seek control, it proceeds to the next step and starts operation.

In step 202, the sub microprocessor 452 monitors for a seek command from the host device 1 instead of the main microprocessor 451 while the main microprocessor 451 is performing seek control. When the seek command is received, the process proceeds to the next step.

The sub-microprocessor 452 determines in step 203
The sub-microprocessor 452 reads the head movement direction register 461 of the RAM 460, the current cylinder 462, the movement cylinder 463, and the movement counter 465 while decoding the seek instruction and recognizing the new target cylinder specified by the seek instruction. It is determined whether the direction in which the microprocessor 451 is moving by the head seek control being executed matches the direction in which the microprocessor 451 moves to the new target cylinder.

That is, the sub-processor 452 reads the registers of the RAM 460 to determine the current head position. This can be known by adding or subtracting the values of the current cylinder 462 and the movement amount counter 465 based on the head movement direction 461. Therefore, based on this, it is determined whether the new target cylinder is in the same direction as the current position and the current head moving direction.

As a result, if the seek direction of the target track is different from the current one, the process proceeds to step 206, where the main microprocessor 451 is interrupted to stop seeking.

This interrupt is performed by setting the RAM460 seek interrupt flag 464. Main microprocessor 451
Since the interruption can be performed only by reading the interruption flag 464 in this seek, even if the head is moved at high speed, the interruption flag 464 can be sufficiently read.

The main microprocessor 451 reads the seek interruption flag in synchronization with the update of the movement amount cylinder 463, etc., and if this flag is “1”, immediately outputs a deceleration instruction to the servo control circuit 454 to move. Quantity cylinder 463
Is set to zero.

As described above, the main microprocessor 451 omits the reception of a new seek command and the decoding of the command and the operations of steps 202 and 203, and the operations of steps 204 and 205 described later, as in the operation of the single microprocessor as in the first embodiment. Since this work is assigned to the sub-processor 452, an interrupt can be accepted during a seek operation even if the head moves at a high speed as in the prior art.

After stopping the seek of the head in this way, the main microprocessor 451 notifies the sub-processor 452 to that effect, and the sub-processor 452 responds accordingly to the step 207.
Transfers the previously accepted seek instruction.

On the other hand, if it is determined in step 203 that the new seek command is the same as the current seek direction, the process proceeds to step 204, where it is determined whether a seek change to a new target cylinder is possible.

This determination is the same as step 123 in FIG. 8, except that the sub-processor 452 makes this determination. If the change is still possible, in step 205, the sub-processor 452 stores the movement amount for the new target cylinder in the movement amount register 463 of the RAM 460.
Set to.

On the other hand, if the head has already passed the new target cylinder, or the head has passed the new target cylinder even after deceleration, the routine proceeds to step 206.

As described above, in the second embodiment, the seek control of the head can be interrupted even if the upper limit of the moving speed of the head 6 is not decreased as compared with the related art, or is decreased only slightly.

As described above, according to the present invention, when a command enters during a seek, the movement of the head can be stopped and the command can be executed at any time, and the throughput is improved.

INDUSTRIAL APPLICABILITY The present invention can constitute a high-throughput magnetic disk device or a magneto-optical disk device. In particular, the present invention is effective in a method of pre-reading a continuous area in a semiconductor memory such as a cache memory in order to increase the speed of these hard disk devices. That is, it is possible to reduce the time required for interrupting the prefetch operation and starting a new seek.

Continuation of the front page (72) Inventor Shuhei Moriyoshi 30-4 Kakinotaidai, Midori-ku, Yokohama-shi, Kanagawa 103 Ogawa Heights 103 (56) References JP-A-57-105061 (JP, A)

Claims (11)

(57) [Claims] An external device transfers data in response to a data read request to an external device, and prefetches data following the data to a memory in a disk control device without receiving an instruction from the external device. A step of performing a seek operation to move the head from a first position where data requested by an external device on the recording medium is present to a remote second position where data to be prefetched is present under the control of the processor ( a) setting a limit speed of a head at which the processor can receive a command from an external device during the execution of the step (a); and (C) detecting whether a command has been received from the device; and (c) receiving the command in the processor. And that when it detects a that is, the step (d) to stop the seek operation to move the head from the first position to the second position; seek control method for a disk apparatus having. 2. The seek control method according to claim 1, wherein the steps (b) and (c) determine whether the second processor has received a command from an external device during the execution of the step (a). (E) detecting whether the command has been received by the second processor in step (e). A seek control method for a disk drive, comprising: a step (f) of stopping a seek operation for moving the head to the position of (b). 3. The seek control method according to claim 1, wherein the command from the external device instructs a seek operation for moving the head to a third position; (F) determining whether the first direction of moving the head to the second position in step (a) is the same as the second direction of moving the head from the current position of the head to the third position; And a step of immediately stopping the head on the recording medium when it is determined in the step that the first direction is different from the second direction. 4. The seek control method according to claim 3, further comprising: moving from the current head position to a third position when it is determined that the first direction and the second direction are the same. Determining whether or not the head can be stopped at the third position; and determining that the head cannot be stopped at the third position, A seek control method for a disk device, comprising a step of immediately stopping on a recording medium. 5. The seek control method according to claim 4, further comprising, when it is determined that the head can be stopped at the third position, executing the command to move the head to the third position. A seek control method for a disk device, comprising the step of: 6. A data read request from an external device is transferred to the external device, and data continuous with the data is prefetched to a memory in the disk control device without receiving an instruction from the external device. At this time, a first seek operation for moving the head from the first position where the data requested by the external device on the recording medium exists to the remote second position where the data to be prefetched exists exists under the control of the processor. Means for setting a limit speed of a head at which the processor can receive a command from an external device during the execution of the seek operation; and Third means for detecting whether or not a command has been received; and third means for detecting that the command has been received by the processor. When the seek control of a disk device and a fourth means for stopping a seek operation to move the head from the first position to the second position. 7. The seek control device according to claim 6, wherein said second means and said third means detect whether a command from an external device has been received during execution of said seek operation. Fifth means having a processor, wherein the third means moves the head from the first position to the second position when detecting that the command has been received by the second processor. A seek control device for a disk drive, comprising: a sixth means for stopping a seek operation. 8. The seek control device according to claim 6, wherein a command from the external device instructs a seek operation for moving the head to a third position; The sixth means is means for determining whether the first direction of moving the head to the second position is the same as the second direction of moving the head from the current position of the head to the third position. A seek control device for a disk device having means for immediately stopping the head on the recording medium when the means determines that the first direction is different from the second direction. 9. The seek control device according to claim 8, further comprising: moving from the current head position to a third position when it is determined that the first direction and the second direction are the same. Means for determining whether or not the head can be stopped at the third position; and determining that the head cannot be stopped at the third position by the means; A seek control device for a disk device having means for immediately stopping on a recording medium. 10. The seek control device according to claim 9, further comprising, when it is determined that the head can be stopped at the third position, executing the command to move the head to the third position. A seek control device for a disk drive having means for moving to a disk drive. 11. The seek control device according to claim 6, wherein the processor is a first processor, and the third means is a second processor.
And a memory means for storing data relating to a seek operation, wherein the second processor refers to the data in the memory means and, after a seek operation by the first means,
A seek control device for a disk drive, comprising means for determining whether or not the above command can be executed.