JPH05282807A - Magnetic disc unit with off-track measuring feature - Google Patents

Abstract

PURPOSE:In a magnetic disc unit with an off-track measuring feature by which the off-track amount inherent in a data head to be corrected when positioning the head is measured during the operation of the unit, to achieve efficient con trol of the offtrack measuring process performed during the operation of the unit. CONSTITUTION:Provided in a higher-order magnetic disc control unit 12 is an off-track measuring control means 52, which instructs a lower-order magnetic disc unit 10 on the measuring process of an off-track amount according to the time schedule stored in a time table 54. The off-track measuring means 52 provided in the lower-order magnetic disc unit 10, upon receipt of the measuring instructions from the offtrack measuring control means, measures and stores the offtrack amount of each data disc 18 with respect to the reference position of a servo disc 14 in a correction table 86.

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 having an off-track measuring function for measuring an off-track amount peculiar to a data head, which is corrected at the time of head positioning, while the device is in motion. Today's magnetic disk devices cannot stop improving performance such as large capacity and high data transfer speed. 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 inch of magnetic disk. The density (TPI) and the recording density (BPI) in the circumferential direction per inch are increasing.

When the recording density is increased in this way,
To prevent the occurrence of off-track due to temperature changes, etc., measure the off-track amount with respect to the reference position,
It is becoming essential to perform off-track correction when positioning the head. 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 host disk control unit. There is no inconvenience, and improvement of this point is desired.

[0003]

2. Description of the Related Art Conventionally, when the track spacing is narrowed and the track density is increased in a magnetic disk device, head positioning control using only servo information on the conventional servo surface adds to the environmental temperature of the device and the head actuator. The data head may be displaced from the servo head due to changes in external force, etc., and even if seek operation is performed, off-track may occur between the target track and stable read / write, and seek operation may not be performed. It causes problems such as stabilization and longer settling time.

Therefore, the servo information is recorded in the data surface, the off-track amount is measured for each data head, and the head is moved 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 a path from the disk control unit to form a subsystem, and this subsystem is connected to a channel of a host computer device.
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 off-track measurement servo information 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, since the magnetic disk unit itself executes the off-track measurement processing independently of the higher-order disk control unit, the higher-order off-track measurement is performed. 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 off-track measurement processing by interruption every time a preset time elapses. Therefore, the off-track measurement process may be started due to an interrupt during the execution of the command chain from the higher-level device, and the execution of the command chain is made to wait 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 of the specified magnetic disk unit whether or not the off-track measurement is being executed, 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 at the same time 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 necessarily 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 such as predicting 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 motion. 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 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 illustrates 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 that decodes a command from a host device and instructs the magnetic disk unit 10 connected under the command to perform a read operation or a write operation.

Here, the magnetic disk unit 10 includes a servo disk 14 that stores servo information, a servo head 16 that reads servo information from the servo disk 14, a plurality of data disks 18 that record 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 controlling the positioning of the data heads 20 to the target cylinder position based on the servo information obtained from the servo heads 16.
Equipped with.

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 process 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 apparatus 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 about 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 magnetic disk devices that are executing a command chain, the off-track measurement command issuance is suppressed and waited until the command chain execution is completed, and the off-track measurement processing is performed using idle time without impairing the command chain execution. And access performance is improved.

Further, since it is unnecessary to inquire whether the off-track measurement is being performed on 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 is possible to open 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, a timer provided for each magnetic disk unit is not required and the control circuit can be simplified.

[0019]

FIG. 2 is a block diagram of an embodiment showing one embodiment of the hardware structure of the present invention. In FIG. 2, the magnetic disk device of the present invention includes a disk control unit 12 located at a higher level and a plurality of magnetic disk units 10-1, 10-connected as subordinates of the disk control unit 12.
2, ... Magnetic disk unit 10-
Numerals 1 and 10-2 represent servo disks 14 and data disks 18-1 to 18-18 rotated by a spindle motor 22 as represented by a magnetic disk unit 10-1.
-3 voice coil motor (called "VCM") 2
Servo head 16 moved in the disk radial direction by 4
And data heads 20-1 to 20-3 are provided.
It should be noted that the number of disks is four as an example, but the number of disks is appropriately set as necessary.

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 its program control. Command control MP for the disk control unit 12
U36 is provided. In the command control MPU 36, a command control unit 50 realized by program control,
An off-track measurement control unit 52 and a timetable 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, the channel control unit 38 for interfacing with
1, 38-2, serial / parallel conversion units 42-1, 4
2-2, the data transfer buffer unit 46 and the system storage unit 48 are connected. From the disk control unit 12 to the magnetic disk units 10-1, 10-2, ..., Two paths 120, 1 are provided in this embodiment.
22 is drawn out, and disk control units 40-1 and 40-2 are provided for the paths 120 and 122, respectively. The disk control units 40-1 and 40-2 are MPU 36 for command control.
From the magnetic disk unit 10-1,
Notify the drive control MPU 26 on the 10-2 side.

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 the 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. 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 the off-track measurement control unit 52 realized by program control. In the operating state after the power is turned on, the subordinate magnetic disk unit 10-according to the time schedule stored in advance in the timetable 54
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, first, when the disk control unit 12 is powered on at time t1, the magnetic disk units 10-1 and 10 are driven according to the power-on sequence.
The power is sequentially turned on in the order of -2, .... In the case of FIG. 3, four magnetic disk units 10-1 to 10 are used.
-4 is connected as an example.

In this way, the magnetic disk unit 10-1
The reason for sequentially turning on the power sources 10 to 10 is that the inrush currents become too large when the power sources are turned on at the same time. When the magnetic disk units 10-1 to 10-4 are powered on, the disk rotation by the spindle motor 22 is started, and when the specified rotation is reached and the initial processing is completed, the rezero operation is performed, and then the power is first supplied at time t2. , A ready interrupt is obtained from the magnetic disk unit 10-1
Subsequently, the other magnetic disk units 10-2 to 1
Ready interrupts are also obtained from 0-4 as indicated 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, set time intervals T ₀ , T ₂ , T ₃ , ... Are stored in advance in the time table 54 of the disk control unit 12 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, and the time intervals for off-track measurement are sequentially lengthened.

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 if the device temperature stabilizes over time, the time interval of off-track measurement is lengthened. Finally, the longest fixed time interval is set. When the first time interval T ₀ elapses at the time t3 under the control of the time schedule by the time table 54, the disk control unit 12 in this embodiment has the magnetic disk units 10-1, 1.
Off-track measurement commands are sequentially generated in the order of 0-2, 10-3, and 10-4 as indicated by the arrows, and in the magnetic disk units 10-1 to 10-4, off-track measurement commands are generated as indicated by the shaded portions. The measurement process is executed.

[0028] Hereinafter, the measurement process by the issuance of the off-track measurement command are similarly for any time interval T _1, T _2, the time t4 T ₃ has passed, t5, t6 are performed. 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 both.

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

In FIG. 5, the disk enclosure 5
In this embodiment, 11 magnetic disks 94 are mounted on the disk rotating shaft 96 rotated by the spindle motor 22 in the casing 6. In the magnetic disk 94, for example, the disk surface at the left end surface is the servo surface, and the other disk surfaces are the data surface. Magnetic disk 94
For the head rotation shaft 100, the head arm 98
Via the servo head 16 and the plurality of data heads 18
The servo head 16 and the data head 18 can be integrally moved in the radial direction of the magnetic disk 94 by rotating the head arm 98 around the head rotation shaft 100.

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 can be rotated around the head rotation axis 100 in accordance with the current flowing in 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 given to the conversion circuit 60. As shown in FIG. 7, the conversion circuit 60 produces an (N> Q) signal [(N + Q)> 0] signal based on the position signals POSN and POSQ from the servo demodulation circuit 58. Further, the track crossing pulse TXPL is generated by the edge detection of these two signals, and the number of passing tracks of the head is obtained by counting by the 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 linearly changes 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
The PU 26 is provided with a servo processing unit including a positioning control unit 62, an addition point 64, and a servo compensating unit 66, which 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 and the head is pulled into the track center.

In the position control for pulling into 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 becomes the signal indicating 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 functions of the off-track correction unit 88 are provided. The off-track measurement unit 84 is the upper disk control unit 1
The off-track measurement processing is executed every time the off-track measurement command is received from 2. 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 as extracted.
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 units of sectors indicated by broken lines in the radial direction. That is, FIG.
As shown in FIG. 1, the first servo information 1 having a frequency at a portion shifted from the track center of the servo information recording track 106 to the outer side by X [μ], for example, the highest writing frequency 1
In the same manner, the second servo information 110 is written in the portion where X [μ] is shifted from the track center to the inner side.
Is writing.

The read signal by the data head 20 when the data head 20 is positioned and controlled on the servo information recording track 106 is as shown in FIG. First, FIG.
As shown in (a), since the servo information 108 and the servo information 110 are uniformly read when the data head 20 is on-track to the track center, 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 detect 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).

The off-track amount in such a magnetic disk unit is measured by the head switching circuit 74, peak hold circuits 76, 78, differential circuit 80 and AD converter in addition to the off-track measuring section 84 provided in the drive control MPU 26. 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
Output 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.
The peak value V1 of the read signal of No. 8 is held. The peak hold circuit 78 also receives the timing control from the drive control MPU 26 and 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.

The differential circuit 80 is a peak hold circuit 76,
The difference signal (V1-V2) of the output signals of 78 is output. This difference signal (V1-V2) is converted into digital data by the AD converter and read by the off-track measurement unit 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.
By repeating this for all 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 the 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, the seek command is received from the upper disk control unit 12 and the data heads 20-1 to 20-n are received.
When seeking to the target cylinder position with the servo head 16 and switching to the positioning control, the off-track amount α is read from the correction table 86 using the head number of the data head defined by the command as an address at this time.

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 of FIG.

In FIG. 12, when a request interruption of the off-track measurement operation is received according to the time schedule based on the time table shown in FIG. 3 in step S11,
In the next step S2, it is determined whether or not the corresponding magnetic disk unit is executing the command chain. Whether the command chain is being executed can be confirmed on the disk control unit 12 side without inquiring 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. Figure 1
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 started 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 the off-track measurement is being executed.
You can tell immediately by inquiring to 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 for which the off-track measurement has been completed to execute the command.

FIG. 14 shows the drive control MPU 26 of FIG.
8 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 upper 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.
In step S2, seek operation of the cylinder position for off-track correction is performed. In step S2, the seek address is waited for. In step S3, the head address = 0 of the data head 20 is first selected, and the off-track amount is measured in step S4. To do.
When the off-track amount is measured, the off-track amount α obtained in step S5 is written in the correction table 86 with the head address = 0 as the 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 1, and then the step S4 is performed again.
To measure the off-track amount. When the measurement of the off-track amount for all the data heads is completed, step S6
To step S7, the process returns to the ready state through the rezero 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. In FIG. 15, the CPU 28 is now
Under the control of, the channel device 27-1 gives a command chain consisting of seek and read to the disk control unit 12. Upon receipt of this command chain, the disk control unit 12 specifies the magnetic disk unit 10-1 and issues a seek command.

When the disk control unit 12 completes issuing the seek command to the magnetic disk unit 10-1, the channel device 27-1 and the disk control unit 12 are sent.
And the path between the disk control unit 12 and the magnetic disk unit 10-1 are separated. Subsequently, the magnetic disk unit 10-1 executes a seek command,
When the seek is completed, a seek complete interrupt is sent to the disk control unit 12. In response to this seek completion interrupt, the disk control unit 12 raises an interrupt to the channel device 27-1, and the path between the channel device 27-1, disk control unit 12 and magnetic disk unit 10-1 is reconnected. It

After recoupling, the magnetic disk unit 10-1
Starts the read operation, and the data obtained by the read operation is transferred 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 issued and then separated 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 during 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 as 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, since the off-track measurement operation of the plurality of magnetic disk units located in the lower order is managed by the upper disk control unit, the execution of the command chain is prevented. The off-track measurement process can be efficiently processed according to the time schedule.

Further, since the status of the off-track measurement can be judged 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 lowered, and the request for other requests is correspondingly reduced. 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 necessary, and the control circuit of the magnetic disk unit can be simplified.

[Brief description of drawings]

FIG. 1 is an explanatory diagram of 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.

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 read signal accompanying off-track of the servo head.

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

FIG. 12 is a flowchart showing off-track measurement control of 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

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[Procedure amendment]

[Submission date] March 3, 1993

[Procedure Amendment 1]

[Document name to be amended] Statement

[Correction target item name] 0009

[Correction method] Change

[Correction content]

The present invention has been made in view of the above-mentioned conventional problems, and a magnetic disk having an off-track measurement function capable of efficiently managing an off-track measurement 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.

[Procedure Amendment 2]

[Document name to be amended] Statement

[Correction target item name] 0026

[Correction method] Change

[Correction content]

When the disk control unit 12 receives the first ready interrupt at time t2, it starts a timer for off-track measurement. Here, set time intervals T ₀ , T ₁ , T ₂ , T ₃ , ... Are stored in advance in the time table 54 of the disk control unit 12 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 for off-track measurement are sequentially lengthened.

[Procedure 3]

[Document name to be amended] Statement

[Correction target item name] 0054

[Correction method] Change

[Correction content]

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 thick 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. Upon receiving this command chain, the disk control unit 12 specifies the magnetic disk unit 10-1 and issues a seek command, and when the issuance 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.

[Procedure amendment 4]

[Document name to be amended] Statement

[Correction target item name] 0055

[Correction method] Change

[Correction content]

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 this 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.

[Procedure Amendment 5]

[Document name to be corrected] Drawing

[Correction target item name] Fig. 15

[Correction method] Change

[Correction content]

FIG. 15

Claims (5)

[Claims] 1. One or a plurality of magnetic disk units (1
0) and a command from a higher-level device, and a disk control unit (12) for commanding a read operation or a write operation to the magnetic disk unit (10) connected thereunder.
A servo disk (14) storing servo information in the magnetic disk unit (10), and a servo head (16) for reading the 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 an 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 each data disk (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 drive 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 power-on of the device. 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 process, 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 process. A magnetic disk drive 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) reads 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 a correction table (86).