JPS61287071A - Magnetic disc controller - Google Patents

Abstract

PURPOSE:To improve the utilization efficiency of a disc drive by so controlling the disc drive that a defective area is skipped and the next area is accessed and transmitting the data at a rate equal to the normal one even when a defective area exists. CONSTITUTION:The logic address of the disc and a transmission sector number are received from the host processor 6 as parameters, and the physical address is calculated by a control means 2. The information to be transmitted is temporarily stored in a buffer memory 5, and is transferred to the magnetic disc by driving it through a drive-interface 3. When a defective area exists, because the means 2 knows the position of the defective track by reading beforehand from a map memory 1 the address corresponding to a cylinder to be accessed each time when the cylinder changes, controls the magnetic disc drive 4 to skip the defective area and access the immediately next area. In such way, the transmission of data is executed at the same rate as the normal rate.

Description

DETAILED DESCRIPTION OF THE INVENTION [Technical Field of the Invention] The present invention relates to a magnetic disk control device that drives a magnetic disk.

[Technical background of the invention and its problems]

If there is a physically defective area of the medium in which neither writing nor reading can be performed on a track of a magnetic disk, input/output of data on the defective track must be performed while avoiding the area. In conventional magnetic disk drives, when reading or writing a file on a magnetic disk, normal access is performed sequentially, but if there is a defective area, the head moves to a pre-prepared alternative area before accessing it. Ta.

However, with the conventional device described above, if there is a defective area,
Compared to the case without this, extra seek time and rotational waiting time are required, which has the disadvantage of slowing down the data transfer speed. That is, FIG. 3(a) is a diagram showing the operating principle of the alternative track method. As shown in the figure, in the case of the alternative track method, the head 11 once moves to the defective track 1.
2, reads that the track is a defective track 12, moves to a substitute track 13 prepared in advance, and after completing the access on the substitute track 13, moves the head to the next track after the defective track 12. 11 is moved, and access is again performed sequentially.

In the case of such an alternative track method, since the track first goes to the defective track 12, then goes to the alternative track 13, and then moves to the next track again, it is necessary to seek one more track than in the normal case.

The seek time for moving the head 11 is the most time consuming in accessing a magnetic disk, and generally the alternative track 13 is located further away than the adjacent track, so the distance traveled is longer, so it is not normal. The drawback was that it took more time than usual. Moreover, with this alternative track method, even if the reading starts at the defective track 12, the reading start position is fixed, so the defective track 12 is immediately read.
There is also the disadvantage that it does not read the information that it is 2, and it may take some time to read it.

FIG. 3(b) is a diagram showing the operating principle of the alternative sector method. As shown in the figure, in the case of the alternative sector method, when the cylinder rotates and the defective sector comes to the head, the head becomes defective. It reads that it is sector 14, rotates the cylinder, accesses it once in alternative sector 15, and then
The next adjacent sector is accessed again. In the case of such a replacement sector method, the waiting time X until the replacement sector 15 rotates, and the waiting time Y until the next sector adjacent to the defective sector rotates from the replacement sector.
However, since the alternative sector 15 is usually located further away than the adjacent sector, it takes more time than normal.

Furthermore, in the case of these methods, since it is necessary to prepare an alternative area in advance, there is a drawback that the use efficiency of the drive becomes poor.

[Purpose of the invention]

The present invention has been made in view of the above circumstances, and provides a magnetic disk that can transfer data at the same speed as normal even if there is a defective area on the magnetic disk, and that improves the utilization efficiency of the magnetic disk drive. The purpose of this invention is to provide a control device.

[Summary of the invention]

The outline of the magnetic disk control device according to the present invention for achieving the above object includes a storage means for storing the position of a defective area of a magnetic disk, a storage means for reading the position of the defective area from the storage means, and a system for skipping the defective area. The present invention is characterized in that it has a control means for controlling the drive of the magnetic disk so as to access the next adjacent area.

[Embodiments of the invention]

An embodiment of the present invention will be described below with reference to the drawings.

FIG. 1 is a block diagram of a magnetic disk control device according to the present invention, and FIG. 2 is a diagram showing a memory for mapping defective tracks. In FIG. 1, 1 is a map memory that stores the position of a defective area on a magnetic disk, and 2 reads the position of the defective area stored in this map memory.
It is a control means for controlling the drive interface 3 to control the magnetic disk drive 4, and 5 is a buffer memory for temporarily storing input/output data.

Furthermore, as shown in FIG. 2, for example, the map memory 1 stores bits of a memory having a sufficient bit width for all tracks in the same cylinder, 0 for a normal track and 0 for a defective track. If it is a track, it is stored as 1. Note that the X direction in the figure is the track number, and the Y direction is the cylinder number.

As the control means 2 of this apparatus, a sequencer, a microprocessor, WO2, etc. is used, and it is software controlled by a microprogram.

The operation of the device configured as described above will be explained below.
This device receives the logical address of the disk and the number of transfer sectors as parameters from the host processor, and uses the control means 2 to calculate the physical address. Further, the information to be transferred is temporarily stored in a buffer memory, and then transferred to the magnetic disk by driving the magnetic disk via the drive interface. At this time, access is normally performed sequentially, but if there is a defective area, the control means 2 reads the corresponding memory address from the Matsubu memory 2 in advance every time the cylinder to be accessed changes, and tracks the defective area in that cylinder. Since we know the location of
The magnetic disk drive 4 is controlled to automatically skip the defective area and access the next adjacent area without accessing the defective area. In other words, the control means 2 reads the 1 or 0 signal in the map memory 1, and if there is a defective area to which a 1 signal is input, it automatically skips that area and moves to the next area adjacent to it. The magnetic disk drive 4 is controlled to move and access.

Therefore, even if there is a defective area, information can be transferred at the same speed as when there is no defective area, and there is no need to prepare an extra area as in conventional devices, making drive utilization more efficient. It is possible to improve the

〔Effect of the invention〕

According to the present invention, even if a magnetic disk has a defective area,
It is possible to provide a magnetic disk control device that can transfer data at the same speed as normal and improve the utilization efficiency of magnetic disk drives.

[Brief explanation of drawings]

FIG. 1 is a block diagram of the magnetic disk control device according to the present invention, FIG. 2 is a diagram showing a memory for mapping defective tracks, and FIG. 3(a) is a diagram showing the operating principle of the alternative track system. FIG. 2B is a diagram showing the operating principle of the alternative sector method. 1...Map memory, 2...Control means, 3...
Drive interface, 4...magnetic disk
Drive, 5...Buffer memory, 6...Upper processor. Agent Patent attorney Noriyuki Chika (and 1 other person) -X Figure 3

Claims (2)

[Claims] (1) A storage means for storing the position of a defective area on a magnetic disk, and a drive for the magnetic disk that reads the position of the defective area from the storage means and controls the magnetic disk drive to skip the defective area and access the next adjacent area. What is claimed is: 1. A magnetic disk control device comprising: control means for controlling a magnetic disk; (2) The magnetic disk control device according to claim 1, wherein a map memory corresponding to the defective area is used as the storage means.