JP2686393B2 - Magnetic disk drive with off-track measurement function - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a magnetic disk drive having an off-track measuring function for measuring the amount of off-track peculiar to a data head to be corrected during head positioning while the device is in motion. The performance of today's magnetic disk devices, such as the increase in capacity and the speed of data transfer, remains unknown. In addition, due to demands from the installation environment such as space saving and power consumption saving of computer centers, and improvement of access time, downsizing of magnetic disk devices is progressing, and radial tracks per 1 inch of magnetic disk. The density (TPI) and the recording density (BPI) in the circumferential direction per inch are increasing.

[0002] When the recording density is increased as described above,
In order to prevent the occurrence of off-track due to temperature change etc., measure the off-track amount with respect to the reference position,
It is becoming essential to perform off-track correction at the time of head positioning. However, the conventional off-track correction is performed independently on the multiple magnetic disk units provided under the disk control unit, and the command chain cannot be executed during measurement, but this is understood by the upper disk control unit. There is no inconvenience, and improvement of this point is desired.

[0003]

2. Description of the Related Art Conventionally, in a magnetic disk drive, when the track interval is narrowed and the track density is increased, the conventional head positioning control using only servo information on a servo surface adds to the environmental temperature of the drive and the head actuator. The data head may be misaligned with respect to the servo head due to a change in external force, etc., and even if a seek operation is performed, off-track may occur between the data track and the target track, and stable reading and writing may not be performed. Problems such as stabilization and long settling time occur.

Therefore, the servo information is recorded in the data surface, the off-track amount is measured for each data head, and the head is directed in the direction of removing the off-track amount measured at the same time as the seek operation by the servo information of the servo surface or at the end of the seek. Off-track correction is performed to move the. Specifically, a plurality of magnetic disk units are connected to the path from the disk control unit to form a subsystem, and this subsystem is connected to the channel of the host computer system.
For off-track measurement, each of the plurality of magnetic disk units connected under the magnetic disk control unit manages its own time schedule, and the off-track measurement process is executed every time the set time elapses. There is.

In this off-track measurement processing, the head is sought outside the magnetic disk data surface to the cylinder position where the servo information for off-track measurement is recorded, and when the seek is completed, the data head is sequentially switched to read the servo information. The off-track amount is detected and stored in the correction table using the head number as the address pointer.

[0006]

However, in such a conventional off-track measurement, the magnetic disk unit itself executes the off-track measurement processing independently of the upper disk control unit. There was a problem that the disk control unit could not grasp the state of the off-track measurement processing in the subordinate magnetic disk unit.

That is, each magnetic disk unit activates a timer used for off-track measurement after completion of activation by turning on the power of the apparatus, and executes an off-track measurement process by interruption every time a preset time elapses. Therefore, the off-track measurement process may be started by an interrupt during the execution of the command chain from the higher-level device, and the execution of the command chain is kept waiting until the off-track measurement process is completed, which lowers the access performance.

Further, when the disk control unit receives a new command chain from the host device, it is necessary to inquire whether or not the off-track measurement is being executed to the designated magnetic disk unit, and the path is occupied during this time.
There is a risk of frequent passivities due to the high access frequency of the pass. Furthermore, the timers that determine the time schedule for off-track measurement are started almost all at once when the startup is completed after the power is turned on, but due to various variations among the magnetic disk units, the count time of the timer is deviated and the timer counts for a long time. The off-track measurement process is executed at random during use. Therefore, even if the off-track measurement processing of a specific magnetic disk unit is known by the disk control unit, other magnetic disk devices do not always have the off-track measurement timing, and the off-track measurement of one magnetic disk unit is known. Therefore, it is also difficult to manage to predict the off-track measurement of other magnetic disk units.

The present invention has been made in view of the above conventional problems, and a magnetic disk having an off-track measuring function capable of efficiently managing the off-track measuring process performed while the apparatus is in operation. The purpose is to provide a device. Another object of the present invention is to provide a magnetic disk device having an off-track measurement function in which a higher-level disk control unit, which is connected under a plurality of magnetic disk units, manages all off-track measurement processing.

Another object of the present invention is to provide an interrupt request for an off-track measurement operation according to a time schedule,
Provided is a magnetic disk device having an off-track measurement function, in which issuance of an off-track measurement command is suppressed during execution of a command chain, and the off-track measurement command is issued after completion of execution of the command chain.

[0011]

FIG. 1 is a diagram illustrating the principle of the present invention. First, the present invention has one or a plurality of magnetic disk units 10 and a disk control unit 12 which decodes a command from a higher-level device and instructs the magnetic disk unit 10 connected thereunder to perform a read operation or a write operation.

The magnetic disk unit 10 includes a servo disk 14 for storing servo information, a servo head 16 for reading servo information from the servo disk 14, a plurality of data disks 18 for recording data, and a plurality of data disks. A plurality of data heads 20 provided for each 18 for writing or reading data, and a drive control unit 26 for positioning and controlling the data heads 20 at a target cylinder position based on servo information obtained from the servo heads 16.
Is provided.

According to the present invention with respect to such a magnetic disk device, the magnetic disk unit 10 is provided in the disk control unit 12, and the magnetic disk unit 10 is instructed to perform an off-track amount measurement process according to the time schedule stored in the time table 54. The servo disk 14 is provided in the track measurement control means 52 and the magnetic disk unit 10 and receives a measurement command from the off-track measurement control section 52.
The off-track measuring means 55 for measuring the off-track amount of each data disk 18 with respect to the reference position and storing it in the correction table 86 is provided.

Here, the off-track measurement control means 52 of the disk control unit 12 commands the off-track measurement processing according to a time table 54 in which time intervals are set according to changes in the environmental temperature immediately after the power of the apparatus is turned on. Specifically, the off-track measurement processing is instructed according to the time table 54 so that the time intervals are sequentially increased with the lapse of time immediately after the power of the device is turned on.

Further, the off-track measurement control means 52 of the disk control unit 12 judges whether the magnetic disk unit 10 is executing the command chain when instructing the off-track measurement processing, and waits for the end of the execution of the command chain. Command the off-track measurement process. Further, the off-track measuring means 55 of the magnetic disk unit 10 reads signals of the first and second servo information 108 and 110 recorded by off-tracking a predetermined amount in different directions with respect to the track center read by the data head 20. The difference signal (V1-V2) is calculated and stored in the correction table 86.

[0016]

According to the magnetic disk device having the off-track measuring function of the present invention having such a configuration, the off-track measuring process of a plurality of magnetic disk units is managed by the upper disk control unit. Therefore, the disk control unit can grasp the entire status of the off-track correction processing without inquiring the subordinate magnetic disk unit.

Therefore, even if an interrupt request is generated at the off-track measurement start timing according to the time schedule,
For a magnetic disk device that is executing a command chain, the off-track measurement command is suppressed and kept waiting until the command chain execution is completed, and the off-track measurement processing is performed using idle time without impairing the execution of the command chain. The access performance is improved.

Further, since it is not necessary to inquire whether the off-track measurement is being performed for the magnetic disk unit, which has been performed every time the command chain is received, the occupancy rate of the path is reduced, and it can be released to other usage requests. Only the processing time becomes faster. Further, since the off-track measurement processing is collectively managed by the disk control unit, the timer provided for each magnetic disk unit is not required and the control circuit can be simplified.

[0019]

FIG. 2 is a block diagram showing an embodiment of a hardware configuration according to the present invention. In FIG. 2, the magnetic disk device of the present invention includes a disk control unit 12 positioned at an upper level and a plurality of magnetic disk units 10-1 and 10- connected under the disk control unit 12.
... Magnetic disk unit 10-
Reference numerals 1 and 10-2 denote a servo disk 14 and a data disk 18-1 to 18-18 which are rotated by a spindle motor 22, as shown by the magnetic disk unit 10-1.
-3 for voice coil motor (referred to as "VCM") 2
Servo head 16 moved in the disk radial direction by 4
And data heads 20-1 to 20-3 are provided.
Although the number of disks is four as an example, they are provided as needed.

Further, a drive control MPU 26 and a read / write section 35 are provided in the magnetic disk unit 10-1. The drive MPU 26 includes the function of the off-track measuring unit 55 under program control. The disk control unit 12 has a command control MP
U36 is provided. In the command control MPU 36, a command control unit 50 realized by program control,
An off-track measurement control section 52 and a time table 54 used for off-track measurement control are provided.

For the command control MPU 36, the upper control channel devices 27-1 and 27 are connected via the internal bus 45.
-2, a channel control unit for interfacing with -2
1, 38-2, serial / parallel converters 42-1, 4
2-2, the data transfer buffer unit 46 and the system storage unit 48 are connected. In this embodiment, two paths 120, 1 are provided from the disk control unit 12 to the magnetic disk units 10-1, 10-2,.
22 are drawn, and disk controllers 40-1 and 40-2 are provided for each of the paths 120 and 122. The disk control units 40-1 and 40-2 are provided by the command control MPU 36.
From the magnetic disk unit 10-1,
The drive control MPU 26 on the 10-2 side is notified.

Further, the serial / parallel converters 42-1 and 42-2 of the disk control unit 12 are provided with data modulators 44-1 and 44-2, and the magnetic disk units 10-1 and 10-2 are provided. Write data or read data is exchanged with the read / write unit 35 via the paths 120 and 122 on the side. The write data or read data is temporarily stored in the data transfer buffer 46 and then transferred to the magnetic disk unit or the host device.

As a host device for the disk control unit 12, the CPU 28 is connected via the channel devices 27-1 and 27-2 and the channel bus 34, and the main storage device (MCU) 30 is used to connect the main storage device ( MS
U) 32 is connected. In such a hardware configuration, according to the present invention, the command control MPU 36 of the disk control unit 12 is provided with an off-track measurement control unit 52 realized by program control. In the operation state after the power is turned on, the subordinate magnetic disk units 10-are controlled according to the time schedule stored in the time table 54 in advance.
An off-track measurement command is generated for 1, 10-2,.

FIG. 3 is a time chart showing a time schedule of off-track measurement control by the off-track measurement control unit 52. In FIG. 3, when the power of the disk control unit 12 is first turned on at time t1, the magnetic disk units 10-1 and 10-1 are turned on in accordance with the power-on sequence.
The power is turned on sequentially in the order of −2,. In the case of FIG. 3, four magnetic disk units 10-1 to 10
-4 is connected as an example.

As described above, the magnetic disk unit 10-1
The reason for sequentially turning on the power supplies 10 to 10-4 is that if the power supplies are turned on at the same time, the rush current becomes too large. When the power of the magnetic disk units 10-1 to 10-4 is turned on, the disk rotation by the spindle motor 22 is started. When the rotation reaches the specified rotation and the initial processing is completed, a re-zero operation is performed. Ready interrupt from the magnetic disk unit 10-1 in which
Thereafter, the other magnetic disk units 10-2 to 10-1
Ready interrupts are also obtained from 0-4 as shown by the arrows.

When the disk control unit 12 receives the first ready interrupt at time t2, it starts a timer for off-track measurement. Here, in the time table 54 of the disk control unit 12, set time intervals T ₀ , T ₁ , T ₂ , T ₃ , ... Are stored in advance in the order of elapsed time from power-on. For example, T ₀ = 3 minutes, T ₁ = 5 minutes, T ₂
= 10 minutes, T ₃ = 20 minutes, so that the time intervals of off-track measurement are sequentially increased.

Since the temperature change of the device is large immediately after the power is turned on, the off-track measurement process is performed at short time intervals, and when the device temperature stabilizes over time, the time interval of off-track measurement is lengthened. Finally, the longest fixed time interval is set. After a lapse of the first time interval T ₀ at time t3 under the control of such a time schedule according to the time table 54, the disk control unit 12 is a magnetic disk unit In the this embodiment 10-1,1
0-2, 10-3, and 10-4, the off-track measurement commands are sequentially generated as indicated by arrows, and the off-track measurement commands are indicated by hatching in the magnetic disk units 10-1 to 10-4. The measurement process is performed.

Thereafter, the measurement process by issuing the off-track measurement command is similarly performed at any of the times t4, t5, and t6 when the time intervals T ₁ , T ₂ , and T ₃ have elapsed. FIG. 4 is a block diagram of an embodiment showing details of the magnetic disk unit of FIG. In FIG. 4, the magnetic disk unit is composed of a drive MPU 26, a disk enclosure 56, and hardware for connecting the two.

The VCM 2 is installed in the disk enclosure 56.
4, a head actuator 72 is provided, and the servo head 16 and a plurality of data heads 18-1 to 18-n are mounted on the head actuator 72. FIG. 5 is an explanatory diagram showing the structure of the disk enclosure 56 of FIG.

In FIG. 5, the disk enclosure 5
In the casing of FIG. 6, eleven magnetic disks 94 are mounted on a disk rotating shaft 96 rotated by the spindle motor 22 in this embodiment. Of the magnetic disks 94, for example, the disk surface at the left end surface is a servo surface, and the other disk surfaces are data surfaces. Magnetic disk 94
To the head arm 98 by the head pivot axis 100.
Via the servo head 16 and the plurality of data heads 18
By rotating the head arm 98 about the head rotation axis 100, the servo head 16 and the data head 18 can be integrally moved in the radial direction of the magnetic disk 94.

As shown in FIG. 6, the head arm 98 side is provided with a coil 104 constituting a VCM on the opposite side via a head turning shaft 100, and a magnetic circuit 102 having a permanent magnet is fixed to the case side. . Therefore, the head arm 98 is rotated around the head turning shaft 100 in accordance with the current flowing through the coil 104 of the VCM, and the positioning of the servo head 16 and the data head 20 at the tip can be integrally controlled.

Referring again to FIG. 4, the servo head 16
The servo signal read by is demodulated by the servo demodulation circuit 58 and converted into two position signals POSN, POSQ,
It is provided to conversion circuit 60. The conversion circuit 60 generates an (N> Q) signal [(N + Q)> 0] based on the position signals POSN and POSQ from the servo demodulation circuit 58 as shown in FIG. A track crossing pulse TXPL is generated by detecting the edges of these two signals, and the number of tracks passed by the head is obtained by counting by a counter.

Further, each signal from the conversion circuit 44 is called into the positioning control section 62 of the drive control MPU 26,
Position data (position signal) that changes linearly for each track shown in FIG. 7 is generated. Of course, the conversion circuit 60
It is also possible to detect the head speed from the cycle of the track crossing pulse TXPL. M for drive control
A servo processing unit including a positioning control unit 62, an addition point 64, and a servo compensation unit 66 is provided in the PU 26, and these are realized by program control. Positioning control unit 62
Performs speed control during seek operation and positioning follow-up control during on-track. That is, when seeking the head to the target track, the head is moved by feedback control of the target speed and the head moving speed. Also,
When the target track is reached by the seek operation, the speed control is switched to the position control to pull the head into the track center.

In the position control for pulling in the track center of the target track, the position control for the VCM 24 is performed via the servo compensating unit 66 so that the position signal shown in FIG. 7 obtained by the positioning control unit 46 always indicates the track center. Output the data. The servo compensator 66 increases the gain of the high frequency part of the servo signal to perform the pull-in phase compensation. The speed or position control data from the drive control MPU 26 is converted into an analog voltage by the DA converter 68, and then power amplified by the power amplifier 70 to drive the VCM 24.

On the other hand, in the drive control MPU 26, an off-track measuring section 84 and a correction table 8 using a RAM are provided.
6 and the function of the off-track correction unit 88 are provided. The off-track measurement unit 84 is the upper disk control unit 1
Every time the off-track measurement command is received from 2, the off-track measurement process is executed. Here, the principle of the off-track measurement processing in the present invention will be described as follows.

FIG. 8 shows the data disk 18 provided in the disk enclosure 56 in an extracted form.
The servo information recording track 106 is provided at a predetermined cylinder position outside the data area 112 shown by the shaded area. Servo information is stored in the servo information recording track 106 in sector units shown by a broken line in the radial direction. That is, FIG.
As shown in FIG. 1, the first servo information 1 having a frequency at a portion shifted by X [μ] from the track center of the servo information recording track 106 to the outer side, for example, the highest writing frequency 1
08 is written, and then the second servo information 110
Is written.

FIG. 10 shows a read signal from the data head 20 when the data head 20 is position-controlled on the servo information recording track 106. First, FIG.
As shown in (a), when the data head 20 is on-track to the track center, the servo information 108 and the servo information 110 are read uniformly, so that the read signals V1 and V2 output from the data head 20 are the same. Become.

Further, as shown in FIG. 10B, when the data head 20 is off-tracked to the outer side, the servo information 108 is read more than the servo information 110, so that the read signal V1 becomes larger than the read signal V2. Further, as shown in FIG. 10C, when the data head 20 is off-tracked to the inner side, the servo information 110 is read more than the servo information 108, so the read signal V2
Becomes larger than the read signal V1.

Therefore, in the off-track measurement process, the servo information recording track 1 obtained from the data head 20 is recorded.
Difference signal (V1-V2) between read signal V1 and V2 from 06
To read the off-track amount. The off-track amount and the read signal (V1-V2) at this time are shown in FIG.
As shown in FIG. 1, it has a constant proportional coefficient (slope) K.

Therefore, the data surface servo information 108, 11
The off-track amount α can be calculated by multiplying the read difference signal (V1−V2) of 0 by the proportional coefficient K. That is, the off-track amount α of the data surface servo information is calculated as α = K × (V1−V2).

To measure the off-track amount in such a magnetic disk unit, in addition to the off-track measuring section 84 provided in the drive control MPU 26, a head switching circuit 74, peak hold circuits 76 and 78, a differential circuit 80 and an AD converter. It is realized by hardware consisting of 82. That is, the data heads 20-1 to 20-n are connected to the head switching circuit 74, and the head switching circuit 74 receives the switching signal from the drive control MPU 26 and sequentially outputs the data heads 20-1 to 20-n. Read signal of 1
It outputs to the peak hold circuits 76 and 78 one by one.

The peak hold circuit 76 receives the timing control from the drive control MPU 26 and records the first servo information 10 recorded on the servo information recording track on the data surface.
8 holds the peak value V1 of the read signal. The peak hold circuit 78 also holds the peak value V2 of the read signal of the second servo information 110 recorded on the servo information recording track 106 on the data surface under the timing control from the drive control MPU 26.

The differential circuit 80 is a peak hold circuit 76,
A difference signal (V1-V2) of the 78 output signals is output. This difference signal (V1-V2) is converted into digital data by an AD converter, and is read into the off-track measuring section 84 of the drive control MPU 26. The off-track measuring unit 84 calculates the off-track amount α using the proportional coefficient K shown in the measuring unit of FIG. 11 and stores the head address of the data head 20-1 in the correction table 86 as an address pointer. The above processing is performed on the remaining data heads 20-2 to
By repeating for all of the data heads 20-n, the off-track amount α for each of the data heads 20-1 to 20-n is stored in the correction table 86.

In a normal access processing operation, the off-track correction section 88 uses the off-track amount stored in the correction table 86 to perform positioning control with off-track correction. That is, receiving the seek command from the upper disk control unit 12, the data heads 20-1 to 20-n
When seek control is performed together with the servo head 16 to the target cylinder position to switch to positioning control, the off-track amount α is read from the correction table 86 using the head number of the data head specified by the command at this time as an address.

The off-track correction unit 88 performs correction to remove the off-track amount by adding the off-track correction amount α to the target position signal from the positioning control unit 62 at that time in the reverse direction, and sets the data head to the target cylinder. Servo information for locating the track center of the corresponding track is generated from the addition point 64, and the VCM 24 is driven to control the positioning of the data head.

The read / write circuit 90 and the read / write control circuit 92 shown in FIG. 4 implement the read / write section 35 shown in FIG. FIG. 12 is a flowchart showing a measurement control process by the off-track measurement control unit 52 provided in the command control MPU 36 of the disk control unit 12 in FIG.

In FIG. 12, when a request interruption of the off-track measurement operation is received in step S11 according to the time schedule based on the time table as shown in FIG.
In the next step S2, it is determined whether or not the corresponding magnetic disk unit is executing the command chain. Whether or not this command chain is being executed can be confirmed on the disk control unit 12 side without inquiring of the magnetic disk unit side.

If the command chain is being executed, it waits for the end of execution and proceeds to step S3 to issue an off-track measurement command to the magnetic disk unit. FIG.
3 is a flow chart showing normal access control by the command control unit 50 provided in the command control MPU 36 of the disk control unit 12 of FIG.

In FIG. 13, the disk control unit 1
When it is activated by turning on the power supply of No. 2, after performing various initializations in step S1, the process proceeds to step S2 to check whether or not a new command chain is received from the upper CPU 28. When a new command chain is received, the process proceeds to step S3, the received command chain is stacked, and then it is checked in step S4 whether the magnetic disk unit designated by the command is currently executing the off-track measurement.

The off-track measurement control unit 5 which has issued the off-track measurement command without inquiring of the magnetic disk unit side whether or not this off-track measurement is being executed.
You can tell immediately by calling 2. If the off-track measurement is being executed, wait for the completion of the measurement execution and then execute step S5.
In step S3, the new command chain stacked in step S3 is issued to the magnetic disk unit whose off-track measurement has been completed to execute the command.

FIG. 14 shows the drive control MPU 26 shown in FIG.
5 is a flowchart showing an off-track measurement process by an off-track measurement unit 84 provided in the. In FIG. 14, when an off-track measurement command is received from the host disk control unit 12, the off-track measurement process is started with this command reception as an interrupt.

The off-track measurement process is first step S1.
Performs the seek operation of the cylinder position for off-track correction, waits for the completion of the seek in step S2, first selects the head address = 0 of the data head 20 in step S3, and executes the measurement of the off-track amount in step S4. I do.
After the measurement of the off-track amount is completed, the off-track amount α obtained in step S5 is written into the correction table 86 using the head address = 0 as an address pointer.

Subsequently, in step S6, it is determined whether or not the head is the final head. If it is not the final head, the process proceeds to step S8, the head number is incremented by one, and then step S4 is performed again.
To measure the off-track amount. When the measurement of the off-track amount for all data heads is completed, step S6
Then, the process proceeds to step S7, and returns to the ready state via the re-zero operation.

FIG. 15 is a time chart showing the processing operation between the channel devices 27-1 and 27-2, the disk control unit 12 and the magnetic disk unit 10-1 in the embodiment of FIG. The part indicated by the bold line is
It shows the combined state of the interfaces. 15, the channel device 2 is now under the control of the CPU 28.
A command chain consisting of seek and read is given to the disk control unit 12 from 7-1. In response to this command chain, the disk control unit 12 issues a seek command by designating the magnetic disk unit 10-1, and when the issue of the seek command is completed, the channel device
The path between 27-1 and the disk control unit 12 is cut off.
Be separated.

The disk control unit 12 which has received a seek instruction to specify the magnetic disk unit 10-1 issues a sea <br/> click command, and completes the issuance of a seek instruction, de I <br/> disk Control unit 12 and magnetic disk unit 10-1
The path between and is cut off. Then the magnetic disk unit 10-1 executes a seek instruction, on up the seek completion interrupt to the disk control unit 12 in the seek completion, di
Disk control unit 12 and magnetic disk unit 10-1
The paths between are rejoined. In response to the seek completion interrupt, the disk control unit 12 causes the channel device 27-1.
To the channel device 27-
Path between the 1 and the disk control unit 1 2 is also recombined.

After recoupling, the magnetic disk unit 10-1
Starts the read operation, and transfers the data obtained by the read operation to the channel device 27- via the disk control unit 12.
1 to end the series of command chains. During execution of such a one-command chain, conventionally, an off-track measurement operation is started on the magnetic disk unit 10-1 side until a seek instruction is interrupted and then rejoined by a seek completion interrupt. When done,
The seek operation is interrupted until the off-track measurement process ends, and the command
Execution of the command chain may be delayed for the off-track measurement processing time as the chain-based seek complete interrupt enters the raised read operation.

However, in the present invention, the issuance of the off-track measurement command is suppressed even if an off-track measurement interrupt request occurs during execution of the command chain, so the command chain is The measurement operation can be performed by waiting for the end of the measurement of the command chain and issuing the off-track measurement command.

In the above embodiment, the servo information recording track 106 is provided outside the data area 112 as shown in FIG. 8, and the data head 20 is sought on the servo information recording track 106 at the time of off-track measurement. Although the off-track measurement process is executed as an example, the servo information 108 and 110 may be written in the empty space of all sectors of the data area 112 as shown in FIG. The off-track measurement process can be performed in exactly the same manner for the servo information recording method in the data plane.

When servo information is recorded on this data surface, the off-track amount can be measured for each cylinder position, so that more accurate off-track correction can be realized.

[0060]

As described above, according to the present invention, the upper disk control unit manages the off-track measurement operation of a plurality of lower magnetic disk units, thus hindering the execution of the command chain. Without it, the off-track measurement process can be efficiently processed according to the time schedule.

Further, since the off-track measurement status can be determined by the upper disk control unit without making an inquiry to the magnetic disk unit, the occupancy rate of the path to the magnetic disk unit is reduced, and the request for other requests is reduced accordingly. Can be assigned to access to increase processing speed. Further, since the disk control unit manages the off-track measurement of a plurality of subordinate magnetic disk units, the timer for starting the measurement is not required and the timer management is not required, and the control circuit of the magnetic disk unit can be simplified.

[Brief description of the drawings]

FIG. 1 is a diagram illustrating the principle of the present invention.

FIG. 2 is a configuration diagram of an embodiment showing a hardware configuration of the present invention.

FIG. 3 is a flowchart showing off-track measurement start control according to the present invention;

FIG. 4 is a configuration diagram of an embodiment showing details of the magnetic disk unit of FIG. 2;

FIG. 5 is a perspective view of a disk enclosure.

FIG. 6 is an explanatory diagram of a disk enclosure.

7 is an explanatory diagram of the processed waveform of the conversion circuit of FIG. 4 and position data obtained as an output signal.

FIG. 8 is an explanatory diagram showing a recording state of data surface servo information.

FIG. 9 is an explanatory diagram showing a positional relationship of servo information with respect to a data head.

FIG. 10 is an explanatory diagram of a servo information reading signal accompanying off-track of a servo head.

FIG. 11 is a characteristic diagram of a servo reading difference signal with respect to an off-track amount.

FIG. 12 is a flowchart showing off-track measurement control according to the present invention.

FIG. 13 is a flowchart showing access control of the disk control unit.

FIG. 14 is a flowchart showing off-track measurement processing of the present invention.

FIG. 15 is a time chart showing the operation between the disk control unit and the magnetic disk unit in the present invention.

[Explanation of symbols]

 10.10-1 to 10-n: Magnetic disk unit 12: Disk control unit 14: Servo disk 16: Servo head 18, 18-1 to 18-n: Data disk 20, 20-1 to 20-n: Data disk 22: Spindle motor 24: Voice coil motor (VCM) 25: Read / write unit 26: Drive control MPU 27-1, 27-2: Channel device 28: CPU 30: Main memory control unit (MCU) 32: Main memory Device (MSU) 34: Channel bus 36: Command control MPU 38-1, 38-2: Channel control unit 40-1, 40-2: Disk control unit 42-1, 42-2: Serial / parallel conversion 44- 1, 44-2: Data modulation / demodulation unit 46: Data transfer buffer unit 48: System storage unit 50: Command control Part 52: Off-track measurement control part 54: Timetable 55: Off-track measurement part 56: Disk enclosure (DE) 58: Servo demodulation circuit 60: Conversion circuit 62: Positioning detection part 64: Addition point 66: Servo compensation part 68: DA converter 70: Power amplifier 72: Head actuator 74: Head switching circuit 76, 78: Peak hold circuit 80: Differential circuit 82: AD converter 84: Off-track detection unit 86: Correction table 88: Off-track correction unit 90: Read / Write circuit 92: Read / write control circuit 94: Magnetic disk 96: Disk rotation axis 98: Head arm 100: Head rotation axis 102: Magnetic circuit 104: Coil 106: Servo information recording track 108, 110: Servo information 112: Data Area 120 , 122: path

Claims (5)

(57) [Claims] And a magnetic disk unit (1).
0) and a disk control unit (12) that decodes a command from a higher-level device and commands the magnetic disk unit (10) connected thereunder to perform a read operation or a write operation.
A servo disk (14) storing servo information in the magnetic disk unit (10), and a servo head (16) for reading servo information of the servo disk (14)
And a plurality of data disks for recording data (18)
A data head (20) provided for each of the plurality of data disks (18) for writing or reading data;
A disk control unit (12) comprising: a drive control section (26) for positioning and controlling the data head (20) to a target cylinder position based on servo information obtained from the servo head (16). ), And off-track measurement control means (5) for instructing the magnetic disk unit (10) to perform an off-track amount measurement process according to a time schedule stored in a time table (54).
2) and of the respective data disks (18) with respect to the reference position of the servo disk (14) when receiving a measurement command from the off-track measurement control section (52) provided in the magnetic disk unit (10). A magnetic disk device having an off-track measuring function, comprising: an off-track measuring means (55) for measuring an off-track amount and storing it in a correction table (86). 2. A magnetic disk device having an off-track measurement function according to claim 1, wherein the off-track measurement control means (52) of the disk control unit (12) comprises:
A magnetic disk device having an off-track measuring function, wherein an off-track measuring process is instructed according to a time table (54) in which a time interval is set according to a change in environmental temperature immediately after power-on of the device. 3. A magnetic disk device magnet having an off-track measurement function according to claim 2, wherein an off-track measurement control means (52) of the disk control unit (12).
Is a magnetic disk device having an off-track measuring function, in which an off-track measuring process is instructed according to a time table (54) so that the time intervals are sequentially lengthened as time elapses immediately after the device is turned on. 4. A magnetic disk device magnet having an off-track measurement function according to claim 2, wherein an off-track measurement control means (52) of the disk control unit (12).
When instructing the off-track measurement processing, it judges whether the magnetic disk unit (10) is executing a command chain, and waits for the end of execution of the command chain to instruct the off-track measurement processing. A magnetic disk device equipped with an off-track measurement function. 5. A magnetic disk device having an off-track measuring function according to claim 2, wherein the off-track measuring means (55) of the magnetic disk unit (10) is a track read by a data head (20). A first off-track recording in different directions with respect to the center
And a magnetic disk device having an off-track measuring function, wherein a difference signal (V1-V2) between read signals of the second servo information (108, 110) is obtained and stored in the correction table (86).