JPH0240182A - Reference position controller for magnetic head of hard disk - Google Patents

Abstract

PURPOSE:To shorten time required for the movement of a magnetic head to a designated sector and the time for the return movement from that position by setting a reference position to return and move the magnetic head after completing access at the position corresponding to a centroid address equivalent to the centroid of the distribution of the number of times of access. CONSTITUTION:A CPU 6 calculates the centroid address equivalent to the centroid of the distribution of the number of times of access at every access, and returns the magnetic head H to the reference position corresponding to the centroid address after completing the access and makes it await the next access. The reference position is set at the position nearest to a cylinder with the highest frequency of access. In such a way, it is possible to shorten the moving time of the magnetic head H to the cylinder in which a designated sector exists in the next access.

Description

DETAILED DESCRIPTION OF THE INVENTION A. Field of Industrial Application This invention relates to a reference position control device for a magnetic head of a hard disk.

B. Prior Art In conventional hard disks, a fixed home position is fixedly determined as a reference position at which the magnetic head should wait.

Therefore, when the magnetic head finishes accessing a certain sector, it is always returned to its home position, and when it next accesses a sector that has been commanded to write or read, it returns from its home position to its designated home position. The magnetic head was being moved to the sector.

Problems to be solved by the C9 invention By the way, there is no problem if the access frequency for all or almost all sectors is almost the same, but in reality, for example, write commands, read commands, etc. Sectors in which programs are stored are generally accessed frequently, but there are also sectors whose access frequency is significantly lower than this.

Therefore, if the home position of the magnetic head is always fixed at a constant position as described above, if a frequently accessed sector is located far from the home position, it will take time for the magnetic head to move to that sector. Also, it takes a long time to return to the home position after the access is completed, and the frequency of such time-consuming accesses is high, resulting in extremely poor access efficiency as a whole.

The present invention has been made in view of the above circumstances, and an object of the present invention is to shorten the time required to move a magnetic head to a designated sector and return therefrom.

90 Means for Solving the Problems In order to achieve the above object, the present invention has the following configuration.

That is, the reference position control device for a magnetic head of a hard disk according to the present invention includes means for updating and storing the number of accesses at the address of the cylinder in which the sector to which the access command is issued exists for each access command; The apparatus includes means for calculating a center of gravity address corresponding to the center of gravity of the distribution of the number of accesses, and means for returning and moving the magnetic head to a reference position corresponding to the center of gravity address after the access is completed.

81 action The effects of the configuration of this invention are as follows.

The reference position to which the magnetic head is returned after the access is completed is a position corresponding to the center of gravity address corresponding to the center of gravity of the distribution of the number of accesses, and this center of gravity address is the one closest to the cylinder address with the highest access frequency.

F. Embodiments Hereinafter, embodiments of the present invention will be described in detail based on the drawings.

FIG. 1 is a schematic diagram of a reference position control device for a magnetic head of a hard disk.

m disk plates D (j) (j=o, 1...m-1) are commonly fixed to a rotating shaft 2 driven by a motor 1 at intervals in the vertical direction.

As shown in FIG. 2, each disk plate D(j) has n cylinders C(j), which are arcuate storage areas concentrically divided on the front and back surfaces.

i) (+-0, 1...n-1). Note that FIG. 2 shows only the front side.

The cylinder C(j, i
) are r sectors S(j,i)b in the circumferential direction, respectively.
(k=o, 1.=.r-1).

In order to distinguish each disk plate D(j) from other disk plates and to distinguish between the front and back surfaces of the disk plate D(j), each disk plate D (
Track number T(j) for each front and back side of j). ,
T(j)+ is attached. T(j). is from above
T(j)+ represents the front surface of the th disk, and T(j)+ represents the back surface of the disk.

For each disk plate D(j), a magnetic head H(j) for reading/writing the surface thereof. The magnetic head H(j)1 for reading/writing the back surface is integrated with the magnetic head H(j)1 for reading/writing the back surface, and is also integrated with the magnetic heads for the front and back surfaces of other disk plates, so that it can move freely in and out of the disk in the radial direction. ing.

That is, each magnetic head H(0). An arm 3 to which ~H(m1)I is attached is supported by an arm support 4, and a head positioner 5 is provided for moving the arm support 4 in the radial direction by a specified amount.

Which sector of which disk board is to be accessed is determined as follows.

That is, the CPU 6 sends the track address ad7, cylinder address adc, and sector address ads to the hard disk controller 8 via the pass line 7. Then, the hard disk controller 8
Head positioner 5 based on cylinder address adc
drives all magnetic heads H(0). ~H(m
1) Move + as one unit to the position of the cylinder where the specified sector exists.

On the other hand, from the time when the rotational position detector 9 detects that the designated sector in the designated cylinder has come to the position of the magnetic head as the disk plate rotates, the designated track (
The magnetic head corresponding to the address (front or back of the disk) is activated, and data is read from or written to the specified sector.

A memory 10 for storing which cylinder has been accessed and how many times is connected to the CPU 6 via a pass line 7. This memory 10 secures an area with addresses equal to the number of cylinders n as a storage area for this access frequency.

For convenience of explanation, these cylinder addresses adc are referred to as AD
, ~AD, , and as shown in FIG. 3, each address AD, -ADL1 . The number of accesses to the cylinder corresponding to is expressed as CT o = CT , , -+. In addition, in the initial state, all access counts CT
o ””' CT fi−+ is “0゛′.

During the read or write operation described above, the CPU 6 sends the track address ad, sector address ads, and cylinder address adc (any one of ADo to ADn-1) to the hard disk controller 8 during the read or write operation described above. ) is sent.

In parallel with this, the CPU 6 adds 1 to the access count CT, which is the content of the cylinder address ADi, and updates and stores it in the memory 10 (CTi 4
-CTl +1). This update storage operation is performed at the same address AD of the memo January O even if the track address adt and sector address ads are different, as long as the cylinder address AD is the same.

The operation at this time is shown in the flowchart of FIG. That is, in step S1, it is determined whether there is a read or write access, and if there is an access, the process advances to step S2, and the number of accesses C is determined at the cylinder address AD sent at the time of the access.
Add 1 to T.

In the routine for calculating the center of gravity address shown in FIG. 5, it is determined in step 311 whether or not a DMA (direct memory access) operation is being executed. If it is, there is free time in the CPU 6; Calculate the center of gravity address using time.

That is, the process advances to step S12, and the average number of accesses C
T s is calculated using the following formula (■).

CTs −(CTo +c'rl+...+CT11
-1)÷n Next, in step S13, the center of gravity address ADX is calculated based on the following formula (2).

ADX'-' (AD, (CT, -CTS) + AD
.

(CT + CTs) 10...+ADl, -I
(CTllCT, ))/ ((CT, -CT, )+
(CT.

CTs)+...+(CT, -ICTS)14
(ADi (CTi -CT, ))Σ(CTi CTS) ・・・・・・・・・・・・・・・・・・■This A
DX' often includes a fraction, but this ADX'
Of the two adjacent addresses sandwiching ADX', the address that is closer to ADX' is determined as the center of gravity address ADX.

Then, in step S14, the center of gravity address ADX is memorized as 5AVEL in January 0, and in step S15, the end of the DMA operation is waited for, and in step S16, the head positioner 5 is controlled via the hard disk controller 8 based on the center of gravity address ADX. , magnetic head H(0). ~H(m
l) Move + to the position corresponding to its center of gravity address ADX and wait for the next access.

This becomes the reference position of the magnetic head, which corresponds to the center of gravity of the distribution of the number of accesses at the present time. The reference position corresponding to this current center of gravity address ADX is as shown in FIG.
This is the position of the cylinder with the highest access frequency in the history of accesses up to now.

Then, in subsequent accesses, there is a high probability that the sector in the cylinder with the highest access frequency will be specified.
The time required for the magnetic head waiting at the reference position to move to the designated sector is sufficiently shortened.

Each time an access is performed, the number of accesses of the address of the cylinder in which the accessed sector exists is incremented by one, so the distribution of the number of accesses changes, and the center of gravity address ADX is accordingly updated.

However, if the specified sector exists in the most frequently accessed cylinder, the updated centroid address A
In most cases, DX is the same as the previous center of gravity address ADX, and does not deviate greatly from the previous center of gravity address ADX.

Therefore, the time required for the magnetic head to return to the reference position corresponding to the updated center of gravity address ADX after completion of access to the designated sector can be shortened.

Even if the designated sector is a cylinder that is accessed infrequently, the number of accesses increases by only 1, so the change in the distribution of the number of accesses is small, and the change in the updated center of gravity address ADX is also small. Therefore, also in this case, the time required for the magnetic head to return to the reference position corresponding to the updated center of gravity address ADX is short.

In the above embodiment, the center of gravity address ADX is calculated by software to determine the reference position at which the magnetic head should wait, but instead of this, it may be configured to be controlled by hardware.

Effect of G1 invention According to this invention, the following effects are exhibited.

That is, for each access, a barycenter address corresponding to the centroid of the distribution of the number of accesses is calculated, and after the access is completed, the magnetic head is moved back to the reference position corresponding to the barycenter address to wait for the next access. The reference position is the one closest to the most frequently accessed cylinder.

Therefore, in the next access, the time required to move the magnetic head to the cylinder where the specified sector exists can be shortened, and a new center of gravity address is calculated by this access, but this center of gravity address is the same as the previous center of gravity address. Since the change does not change much, the time required to return the magnetic head to the reference position corresponding to the new center of gravity address after the access is completed can also be shortened.

As a result, overall access efficiency can be significantly improved.

[Brief explanation of the drawing]

1 to 6 relate to an embodiment of the present invention, in which FIG. 1 is a schematic configuration diagram of a reference position control device for a magnetic head of a hard disk, FIG. 2 is a plan view of a disk plate, and FIG. 3 is an access count. 4 and 5 are flowcharts for explaining the operation, and FIG. 6 is a distribution diagram of the number of accesses. 5...Head positioner 6...CPU (center of gravity address calculation means) 8...Hard disk controller 10...Memory (access number update storage means) C(j
, i)...Cylinder S(j,i),...Sector AD,...Cylinder address CT,...Access count ADX...Gravity center address H(0)o ~ H(m-1) 1-Magnetic head\kuIkuζ9゜ku

Claims (1)

[Claims] (1) Means for updating and storing the number of accesses at the address of the cylinder in which the sector to which the access command is issued exists for each access command; A reference position control device for a magnetic head of a hard disk, comprising means for calculating, and means for returning and moving the magnetic head to a reference position corresponding to the center of gravity address after access is completed.