JPH0547109A - Magnetic disk device - Google Patents

Abstract

PURPOSE:To contrive shortening a full processing time by making a timing for transition from a seeking operation to the read operation of a head faster than a timing for transition from a write operation to the read operation. CONSTITUTION:The output of a timer 4 is reported toa processor HOST as a positioning completion signal and the HOST issues a read instruction and a write instruction. The read instruction is sent to the read circuit 9 of a magnetic disk device 100 through the read control circuit 7 of a disk controller DKU 200 unconditionally and the read operation is executed. On the other hand, an AND condition is determined between the write instruction and the output of a timer 5, that is, a writable signal from the DKU 100 in the DKC 200, and the write operation is executed after settling of overshooting and undershooting. Consequently, positional deviation of the magnetic head and an error of write are hardly generated in a write process. Also, a read process can be executed on the halfway of settling of the shootings then processing speed is improved.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a magnetic disk device, and more particularly to a magnetic disk device capable of shortening data recording / reproducing processing time.

[0002]

2. Description of the Related Art A magnetic disk device, when connected to a host processor and used as a random access file,
Since the access time is relatively long, the access device is not always connected to the processing device at all times, and is generally disconnected from the processing device after receiving a command from the processing device via the disk control device. For example, when a seek command is issued from the host processor, the disk controller that receives this command controls the magnetic disk device to execute this seek command, disconnects the processor from the controller, and removes the magnetic disk. Wait for the seek operation completion report from the device. When this seek operation is completed, the disk control device reports the completion of the seek operation to the processing device, reconnects the processing device and the disk control device, and issues a command as to which position of a predetermined track is to be recorded / reproduced. Received from the processing unit. The position on this track is usually called the set sector. Upon receiving this set sector command, the disk controller disconnects from the processing device again, instructs the magnetic disk device to search for the set sector, and after the magnetic disk device finds the set sector, the processing device. And the magnetic disk device are reconnected to record / reproduce data.

As a procedure for the seek command processing to be completed and the command of the next set sector to be received, the magnetic disk device configured as described above does not accept the next command unless the seek command is completed. There is. Therefore, since it takes time from the end of the seek command processing until the command of the set sector is received, the conventional magnetic disk device has a problem that an unnecessary command waiting time is added to the entire processing time of recording / reproducing. there were.

In order to solve this problem, a conventional technique for promptly reporting a seek completion is disclosed in Japanese Patent Laid-Open No. 58-1591.
No. 66 publication. This technique is to perform a seek completion report early when the moving positioning speed of the magnetic head becomes equal to or lower than a predetermined speed.

[0005]

The processing after the magnetic head positioning according to the above-mentioned prior art is premised on that a set sector processing command is always input from the processing device. However, in actual processing, after the seek command, data may be directly read or directly written without a set sector instruction. In this case, even if the magnetic head is not positioned on the target track, a read / write processing command is issued from the processing device, and read / write is performed in order to perform recording / reproduction at a position other than the target track. It causes a problem that an error occurs.

An object of the present invention is to consider the case where direct read / write processing is performed by performing the set sector processing, and the read processing is more unstable than the write processing even if the magnetic head is slightly unstable. That is, paying attention to the fact that it can be executed even if the position of the track and the magnetic head are slightly deviated, the magnetic head positioning completion report is clearly divided into a readable / writable area and a readable / writable area for processing. To report to the device. The processor can read the report and execute the reading process quickly, and the processing time as a whole can be shortened.

[0007]

In order to achieve this object, the present invention provides a detecting means for detecting that a magnetic head is ready to read data on a target track during execution of a seek instruction, and the detecting means. When the approach of the magnetic head is detected by the means, it is judged whether the instruction from the next processing device is a read instruction or a write instruction. It is characterized in that the head is provided with control means for performing writing after stabilizing on the target track.

The detecting means may detect that the magnetic head is in the vicinity of the target track by the read voltage from the magnetic head (servo head), or use a timer to estimate the stable state in time. Is also good.

The magnetic head is positioned at the center of the track after oscillating by repeating overshoot, undershoot and undershoot after reaching the target track to be positioned. The overshoot and undershoot decrease with time, and the data can be read accordingly.

When the read voltage from the magnetic head (servo head) exceeds a certain value, or after a lapse of a predetermined time by a timer, the detection means instructs the control means to perform detection, and the control means receives this. It is determined what process the next command from the processor is, and if the next command is a read, the immediate read operation is executed. If it is a write process, the read voltage is It operates so as to write data after a predetermined voltage of 2 or a second predetermined time has elapsed.

As a result, even if overshooting or undershooting occurs, it is possible to carry out the reading process and prevent the occurrence of an error during writing.

[0012]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described in detail below with reference to the drawings. First, a first embodiment in which the detecting means monitors time will be described with reference to FIG.

In FIG. 1, 100 is a disk device (D
KU) 200 is a disk controller (DKC), HOST
Indicates a processing device. Seek command from HOST is DK
It is sent to the carriage drive circuit 2 of the DKU 100 via the seek control circuit 1 of the C200. The DKU 100 has a position detection circuit 3 and timers 4 and 5 for detecting that the magnetic head has reached a specified track, and the operating points of each circuit are shown in the timing chart of FIG. The read command from the HOST is sent to the read circuit 9 of the DKU 100 via the read control circuit 7 of the DKC 200. In addition, the write command is D in the DKC200.
The condition of the output of the timer 5 from the KU100 and the AND circuit 10 is satisfied, and the DKU10 is supplied via the write control circuit 6.
0 is sent to the writing circuit 8. The result of the condition being taken by the AND circuit 10 is reported to the control circuit 11. HOS
The seek command from T is translated by the seek control circuit 1 of the DKC 200 into commands such as the amount of movement of the carriage and the moving direction, and is issued to the carriage drive circuit 2 of the DKU 100. Based on this command, the DKU 100 moves the carriage, and when the magnetic head attached to the carriage reaches the target track, the position detection circuit 3 operates and the timers 4 and 5 start timing. The timing at this time is shown in FIG. 2A.
Shown in dots.

After reaching the target track, the magnetic head overshoots and undershoots as shown in FIG.
It decays over time and eventually settles and is centered on the track. On the other hand, the timers 4 and 5 are preset with the time T _R / T _W , operate from the point A, and the output signal changes positively at the points R and W, respectively. The overshoot amount of the magnetic head at this time is such that the R point is a level where the writing process is not possible but the reading process is possible, and the W point is a level where both the reading process and the writing process are possible. The output of the timer 4 is reported to the HOST as a positioning completion signal, and the HOST issues a read command and a write command. Read command is unconditionally DKC
It is sent to the read circuit 9 of the DKU 100 via the read control circuit 7 of 200 to execute the read operation. The write command takes an AND condition with the output signal of the timer 5, that is, the write enable signal, from the DKU in the DKC 200, and if correct, the DKU 1 is sent via the write control circuit 6.
00 to the write circuit 8 and the write operation is executed.
On the other hand, when the AND condition is not satisfied, that is, the timer 5
When the output signal is negative, the write control circuit 6 of the DKC200
Is prohibited, and the control circuit 11 instructs the re-execution of writing after waiting until the output signal of the timer 5 changes to positive. In normal processing, the target record is searched while performing a read process after a seek, and the write process starts after the records match, but the probability that the target record will come immediately after the seek is very small, and the waiting time for rotation is Since this occurs, the write is rarely re-executed, and the processing time delay due to re-execution can be ignored.

According to the present embodiment, since the write processing is executed after the overshoot / undershoot of the magnetic head is reduced, the write processing is not performed due to the positional deviation of the magnetic head, and the read processing is performed. Since it is executed even while the overshoot / undershoot of the magnetic head is being settled down, the stabilization time of the magnetic head can be saved and the processing speed can be improved.

Next, a second embodiment will be described with reference to FIGS. 3 and 4. 3 and 4 show a magnetic disk device according to a second embodiment of the present invention (which detects that a magnetic head can reproduce data of a target track by a read voltage of a magnetic head (including a servo head)). It is a system block diagram and operation | movement explanatory drawing containing.

In the figure, when a processing unit (CPU) 400 issues a data addressing and data transmission / reception command to the magnetic disk unit 100, a disk controller (DK)
C) 200 gives this command to the head movement control unit 30 of the magnetic disk device 100. Thereby, the control unit 30
Is a speed control unit 40 and a VCM (voice coil motor)
VCM (Voice Coil Motor) 101 via amplifier 7
Are driven to start the movement of the magnetic head and the servo head 120. Since the magnetic head and the servo head 120 are moved integrally, the following description will focus on the operation and control of the servo head. The servo head 1
The speed and position of the head 20 are detected by the speed detector 50 and the position detector 60 via the preamplifier 80 based on the signal from the head 120, and are fed back to the head movement controller 30.

Now, the DKC 200 receives in advance a send / receive command following the seek command from the CPU 400, decodes this, and in the case of a data read command, compares the slice level of the position detection signal to the position detector 60. The slice control signal 210 is generated so that it becomes higher. That is, the DKC 200 causes the position detector 60 to detect that the head 110 is turned on on the target track even when the head 110 is on the target track but the overshoot and the undershoot are relatively large.
As a result, the position detection unit 60 sends a seek completion report 220 to the DKC 200, and data reading is performed by a magnetic head (not shown) via the read / write amplifier 90.

This operation will be described with reference to the time chart of FIG. First, the DKC 200 uses the head movement control unit 30.
To the DKC, when a seek command 230 is issued to the
200 transmits a slice level control signal 210 to the position detector 60 so that the slice level for position detection becomes high. As a result, the position detector 60
Even if the position signal 240 is relatively vibrating,
The seek completion report 220 is performed and the read operation is started.

When the command from the CPU 400 is a write command, the DKC 200 tells the position detector 60
The slice level control signal 220 is issued so that the slice level of the position signal is lowered, that is, narrowed. As a result, the write operation is started at the time when the overshoot and undershoot of the head are reduced, so that the write error can be prevented.

According to the above two embodiments, the write operation is performed after the head is stable and the read operation is started in a state where the head is slightly vibrated, so that the processing time of the entire disk device can be reduced.

According to this embodiment, the average access time at the time of reading data can be shortened only by (T ₁ + T ₂ ). Normally (T ₁ + T ₂ ) is about 4 msec, and the effect after application of the present invention in a magnetic disk device that operates with an average access time of 23 msec is [23-4 / 2] = 21.
It becomes msec and improves by 2 msec (about 9%). 4 ms
The value of ec is 1/2 when it is considered that the occurrence probability of writing and reading is equal, but in the actual use state of the entire system, the probability of reading is high as the probability of reading and writing. Therefore, further effects can be expected. In this embodiment, the recording / reproduction is controlled based on the reproduction signal from the servo head, but a magnetic head for data reproduction may be used.

[0023]

According to the present invention, data reproduction is started only when data is read even when the head is unstable, so that the overall processing time can be shortened and an error can be prevented from occurring during data writing. it can.

[Brief description of drawings]

FIG. 1 is a system configuration diagram of a magnetic disk device according to a first embodiment of the present invention.

FIG. 2 is a diagram showing an operation time chart of the magnetic disk device according to the first embodiment of the present invention.

FIG. 3 is a system configuration diagram of a magnetic disk device according to a second embodiment of the present invention.

FIG. 4 is a diagram showing an operation time chart of the magnetic disk device according to the second embodiment of the present invention.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 ... Seek control circuit, 3 ... Position detection circuit, 4, 5 ... Timer, 6 ... Write control circuit, 7 ... Read control circuit, 30 ... Head movement control section, 40 ... Speed control section, 60 ... Position detection section, 100 ... magnetic disk device, 200 ... disk control device.

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Yuji Yoshida 2880, Kozu, Odawara-shi, Kanagawa Stock company Hitachi Ltd. Odawara factory (72) Inventor Kiyotaka Takahashi 2880, Kozu, Kanagawa Prefecture Hitachi Computer Equipment Co., Ltd. (72) Inventor Tsuneo Hirose 2880, Kozu, Odawara-shi, Kanagawa Hitachi Ltd. Odawara Plant (72) Inventor Katsuhiro Tsuneda 2880, Kozu, Odawara, Kanagawa Hitachi Ltd. Odawara Plant (72) Inventor Nakano Riichi Kanagawa Prefecture, Odawara City, Kunifu 2880, Ltd.Hitachi, Ltd.Odawara Plant (72) Inventor Kazuto Takahashi Kanagawa Prefecture, Odawara, City, Kunizu 2880, Ltd.Hitachi, Ltd.Odawara Plant (72) Inventor, Akira Kurano Odawara, Kanagawa Prefecture 2880, Kozu, Ichi Hitachi, Ltd. (72) Inventor Tadayuki Ichiba 2880, Kozu, Odawara City, Kanagawa Stock Company Hitachi Ltd., Odawara Factory

Claims (1)

[Claims] 1. A magnetic disk device comprising a magnetic disk, a magnetic head, and positioning means for positioning the magnetic head on a target track on the magnetic disk, and detecting that the magnetic head has reached a target track. And a control means for starting the recording / reproducing operation by the magnetic head based on the count value of the timer means. Magnetic disk drive.