JPH07169195A - Recording medium read-out device - Google Patents

Abstract

PURPOSE:To shorten access time at the time of data read-outs. CONSTITUTION:Heads 101, 201 are provided in accordance with magnetic disks 102, 202 in which same data are recorded. Respective read-out ranges of magnetic disks 102, 202 are bisected and the bisected ranges are allotted to heads 101, 201 so that the range for one head is different from the range for an other head. In which of divided ranges a read-out range related to a read-out request from a host device is included, is decided by a controller part 30 and the controller 30 control a head so that the head allotted to an instructed range performs a read-out with respect to the range by the decided result. Thus, since read-out ranges allotted to heads are narrow, access time is shortened in so far as data read-out operations are continued.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a recording medium reading device, and more particularly to a recording medium reading device having a plurality of recording mediums on which the same data are recorded.

[0002]

2. Description of the Related Art Conventionally, a mirroring technique (duplication) is applied to a device that accesses a recording medium to improve the reliability of the device. This will be described with reference to FIG.

FIG. 3 is a block diagram showing a configuration when a duplication technique is applied to a magnetic disk device. In the figure, a magnetic disk device 10 includes two magnetic disk drives 1 and 2, and a controller unit 30 that controls the drives 1 and 2 in response to a data access request from a host device such as a host computer (not shown). It is configured to include and.

The magnetic disk drives 1 and 2 include magnetic disks 102 and 202, which are recording media, and heads 101 and 102, which are provided corresponding to the magnetic disks and which access the corresponding disks, respectively. Has been done. The access ranges of the heads 101 and 102 for the conventional magnetic disk drives 1 and 2 are the same, and are indicated by reference numerals 100 and 200 in the figure. That is, the heads 101 and 102 are both magnetic disks 1.
It was controlled by the controller unit 30 so as to access the entire range of 02 and 202 (all cylinders). That is, in this conventional magnetic disk device, the two magnetic disk drives 1 and 2 are controlled so as to write the same data to the same address, thereby increasing the redundancy of data and improving the reliability of the device. Was being improved.

Further, when data is read by the two magnetic disk drives 1 and 2, the entire range of the magnetic disks 102 and 202 is to be read, and both disks are read at the same time. As a result, even if an error occurs in one read operation, the target data can be obtained correctly as long as the other read operation is normal. Depending on the type of device, one of the two magnetic disk drives is used as the current disk and the other is used as the backup disk, and the disk drive of the backup disk is read only when an error occurs in the read operation of the disk disk of the current disk drive. There is also.

Next, the operation of reading from two magnetic disk drives will be described with reference to FIG. FIG. 4 is a flowchart showing a reading procedure in the duplicated magnetic disk device.

In the figure, the controller unit 30 which has received a data request from the host device (step 31) issues a read request to one or two drives (step 32).

When the read operation has no error and the data is normally received, the data is transferred to the host device (host) (steps 33 → 34 → 35 → 36).

If an error occurs in the read operation or an error occurs during data reception, the process for that drive is completed (step 33 → 37, step 35 → 37).

[0010]

As described above, in the conventional magnetic disk device, the entire range of the magnetic disk of each drive is the access target when reading data, and the address where the requested data exists. Both the maximum seek time and the average seek time are the same as the seek time of the drive alone, and it has been desired to shorten the seek time.

Known techniques for shortening the seek time include:
Japanese Unexamined Patent Publication No. 1-173367 discloses a technique of predicting a seek time and reading from a drive predicted to be short. Japanese Patent Laid-Open No. 3-214463 discloses a technique for reducing the rotation waiting time by making the rotation phases of two drives different from each other. However, these techniques have the drawback of being complicated to control.

The present invention has been made in order to solve the above-mentioned drawbacks of the prior art, and an object thereof is to provide a recording medium reading apparatus capable of shortening the access time at the time of reading data by simple control. That is.

[0013]

In a recording medium reading device according to the present invention, the same data is recorded in the first device.
~ Nth (N is an integer of 2 or more) recording medium, and the first to
A recording medium reading device having first to Nth heads provided corresponding to the Nth recording medium and reading data from the corresponding recording medium, the recording medium reading device comprising: Each read range is divided into N, and each N divided range is assigned to the first to Nth heads so as to be different from the ranges of other heads.

[0014]

Embodiments of the present invention will now be described with reference to the drawings.

FIG. 2 is a block diagram showing the configuration of an embodiment of a recording medium reading device according to the present invention, and the same portions as those in FIG. 3 are designated by the same reference numerals. Also in FIG.
Similar to FIG. 3, the configuration when the duplication technique is applied to the magnetic disk device is shown.

In the figure, the magnetic disk device of this embodiment is different from the conventional one in that the access ranges of the magnetic disks 102 and 202 during reading are different from each other. That is, the access range of the magnetic disk 102 is a portion indicated by reference numeral 100, and the magnetic disk 20
The access range of 2 is a portion indicated by reference numeral 200,
It is assumed that the number of cylinders included in both ranges is the same.

That is, two magnetic disks 102 and 202 on which the same data are recorded and two heads 101 and 201 which are provided corresponding to these magnetic disks and read data from the corresponding disks are provided. Assuming that the apparatus has the same, the read range of each of these magnetic disks is divided into two in advance, and each of the two divided ranges is assigned to the two heads 101 and 201 so as to be different from the ranges of the other heads. Therefore, the read range assigned to each head is narrower than in the conventional case.

When there is a data read request from a higher-level device (not shown), the controller unit 30 determines which of the pre-divided ranges the read range associated with the read request belongs to. The controller unit 30 controls so that the heads assigned to the range indicated by the determination result read out the range.

As a result, when the data read operation is continuous, the seek operation is performed on the half of the access range of the single magnetic disk drive, so that the access time at the time of data read is shortened. You can Immediately after the data writing operation is performed, all heads are located in the same cylinder, so the access time at the time of data reading is the same as that of the conventional device. Therefore, the effect of shortening the access time can be obtained only when the data read operation is continuous.

Next, the above read operation will be described with reference to FIG. FIG. 1 is a flowchart showing a read procedure in the magnetic disk device of this embodiment.

In the figure, the controller unit 30 which has received a request for data from a higher-level device (step 11) determines which range of the pre-divided ranges the range in which the data related to the request is recorded is included. Judgment (step 12). Then, the head assigned to the range indicated by the determination result issues a read request to only one of the drives 1 and 2 so that the head reads the range (step 13).

When no error occurs in the read operation and the data is normally received, the data is transferred to the host device (host) (steps 14 → 15 → 16 → 17).

On the other hand, if an error occurs in the read operation,
If an error occurs during data reception, a read request is issued to the other drive (step 1
8). If no error occurs in the read operation and the data is normally received, the data is transferred to the host device (steps 19 → 20 → 21 → 17).

Further, an error occurs in the read operation,
If an error occurs during data reception, the process ends (step 19 → 22, step 21 → 2).
2).

Note that the above is related to the data read operation, and the data write operation writes the same data to two drives at the same time regardless of the allocated range. Even if the error occurs, the data can be read from the other side, and the redundancy of the data inherent to the device is not impaired.

As described above, when the read range of each recording medium is divided and each of the divided ranges is assigned to each head so as to be different from the ranges of other heads, when the data read operation is continuous. Since the seek operation is performed in a half range narrower than the access range of the single magnetic disk drive, the average seek time becomes 1/2 and the access time at the time of data reading can be shortened.

In this embodiment, the case where the number of cylinders in the read range pre-assigned to each recording medium is the same has been described, but different read ranges may be assigned, and the present invention is not limited to this case.

Further, although the case where the recording medium is a magnetic disk has been described in the present embodiment, it is obvious that the present invention is widely applicable not only to the case where it is an optical disk or a magnetic tape.

Further, although the present embodiment has been described on the premise of the double structure, it is clear that the present invention can be applied to not only the double structure but also the triple structure and the quad structure.

[0030]

As described above, the present invention has a simple configuration in which the access range for reading data from each magnetic disk is divided and assigned in advance. Since the seek operation is performed on a narrower access range of the magnetic disk drive, there is an effect that the access time at the time of data reading can be shortened.

[Brief description of drawings]

FIG. 1 is a flowchart showing a data reading procedure in a recording medium reading device according to an embodiment of the present invention.

FIG. 2 is a block diagram showing a configuration of a recording medium reading device according to an embodiment of the present invention.

FIG. 3 is a block diagram showing a configuration of a conventional recording medium reading device.

FIG. 4 is a flowchart showing a data reading procedure in a conventional recording medium reading device.

[Explanation of symbols]

 1, 2 magnetic disk drive 30 controller section 100, 200 access range 101, 201 head 102, 202 magnetic disk

Claims (5)

[Claims] 1. A first to Nth (N is an integer of 2 or more) recording medium on which the same data are recorded, and the first recording medium.
A recording medium reading device having first to Nth heads provided corresponding to the Nth recording medium and reading data from the corresponding recording medium, wherein the first to Nth recording mediums Recording medium reading apparatus, wherein each reading range is divided into N and each N divided range is allocated to the first to Nth heads differently from the ranges of other heads. . 2. The allocating means includes a determining means for determining which of the N-divided ranges the reading range requested by a higher-level device belongs to, and a result of the determination. 2. The recording medium reading device according to claim 1, further comprising: a control unit that controls a head assigned to the range to read the range. 3. The recording medium reading device according to claim 1, wherein the recording medium is a magnetic disk. 4. The recording medium reading device according to claim 3, wherein N is 2 and the numbers of cylinders in the ranges assigned to the first and Nth heads are equal to each other. 5. When data read from the corresponding recording medium by any of the first to Nth heads is abnormal, the heads other than the read data read data to be read by the heads having the read abnormality. 5. The recording medium reading device according to claim 1, further comprising means for controlling to read from a recording medium corresponding to the head.