JPH01197832A - Magnetic disk access method - Google Patents

Abstract

PURPOSE:To reduce a control from a host device, especially a file managing function by a software by likening plural magnetic disk devices of the same kind as one set of virtual magnetic disk device. CONSTITUTION:By assigning continuous track numbers to the same cylinders of plural magnetic disk devices 3, 4, plural magnetic disk device 3, 4 are likened as a host device 1 being one set of virtual magnetic disk device. In this state, when a track number is designated by the host device 1, a magnetic disk control ler 2 executes a seek address conversion and executes an access to a track of the corresponding magnetic disk device. In such a way, the burden of a software of the magnetic disk controller 2 can be reduced.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention provides a magnetic disk access method for a magnetic disk device subsystem consisting of a plurality of magnetic disk devices and a magnetic disk control device that controls these magnetic disk devices. Regarding.

(Prior Art) Conventionally, in this type of system, as the amount of data to be stored increases and the storage capacity of the magnetic disk device becomes insufficient, additional devices have been installed as a countermeasure.

Note that since a control device which is a host device of a magnetic disk device can connect and control a plurality of magnetic disk devices, they are often added under the same control device.

FIG. 4 is a configuration diagram of a conventional magnetic disk drive subsystem. The host device 21 specifies and accesses the magnetic disk device. For example, a predetermined data storage position of the magnetic disk device 23 is designated and the magnetic disk controller 22 is instructed to read or write data. At this time, instructions from the host device 21 are basically performed by software. The software creates a file, which is a set of a certain set of data, in the magnetic disk device 23, and the software recognizes the performance and functions of the device and sets a predetermined storage area. Specifically, files are allocated from a track on one cylinder to a track on another cylinder. That is, the software recognizes the number of tracks in a cylinder and, for example, after accessing all the data in one cylinder, accesses the data in the next cylinder's tracks. However, files are managed within the volume of one device, so if a file is very large, it cannot be stored on one device and must be accessed from another device (such as a disk device). Other new controls such as these will be required. Also,"
As mentioned above, if there are many files, even if they are not just one file, that cannot be stored on one device and multiple devices are prepared, when accessing a file, it is difficult to know which device the file is stored on. You have to be aware of it. When there are multiple devices (volumes) in this way, it becomes difficult to handle files.

(Problem to be Solved by the Invention) In the conventional magnetic disk access method described above, the data to be stored and referenced is stored in the volumes of multiple devices. Access must be controlled, and there is a drawback that software support is required when adding devices.

[Means to solve the problem]

The magnetic disk access method of the present invention allocates consecutive track numbers to the same cylinder of a plurality of magnetic disk devices, presents the plurality of magnetic disk devices as one virtual magnetic disk device to a host device, and controls the magnetic disk. When the track number is designated by the host device, the device performs seek address conversion to access the corresponding track of the magnetic disk device.

(Function) Therefore, the burden on the software of the magnetic disk control device can be reduced.

(Example) Next, an example of the present invention will be described with reference to the drawings.

FIG. 1 is a configuration diagram of an embodiment of a magnetic disk device subsystem to which the magnetic access method of the present invention is applied, FIG. 2 is a flowchart showing control of the magnetic disk controller 5A, and FIG. 3 is a magnetic disk device subsystem. 3.4 track map.

The magnetic disk control device 2 is connected to two magnetic disk devices 3 and 4, and controls the operation of each device.

The magnetic disk devices 3 and 4 are devices having exactly the same performance and functions. The magnetic disk control device 2 is also connected to the host device 1, receives operation requests from the host device 1, and reports after the operation is completed.

Next, the operation of the magnetic disk control device 2 will be explained with reference to FIG. When receiving an access request to the magnetic disk device 3 from the host device 1, the magnetic disk control device 2 first causes the magnetic disk subsystem to make multiple magnetic disk devices as described above appear as a single virtual disk device. Determine whether to perform the action (step +1). This mode may be instructed in advance to the magnetic disk control device 2 by the host device 1, or it can be set to 8 spins in any way by manually operating a changeover switch in the magnetic disk control device 2. It is. In this determination, if it is determined that it is not treated as the above-mentioned virtual device, a conventional access operation to a normal disk device is executed (step +4). If the access is determined to be treated as a virtual disk device.

Convert the seek address (step +2).

When the magnetic disk devices 3 and 4 each have n tracks per cylinder (n heads), the number of tracks per cylinder visible from the L-position device 1 is 2n. FIG. 3 shows this track map, and the virtual disk device has 0 to 2n-1 tracks for each cylinder. Tracks 0 to n-1 are host device 1
If specified, 0 to n-1 of the magnetic disk device 3
If n to 2n-1 tracks are specified, then n to 2n-1 tracks are specified.
The operation is performed to access the 0 to n-1 tracks decreased by the same amount. This makes it possible to perform a seek operation to the required data storage area across the two magnetic disk drives 3.4. Next, a write/read operation to the track selected in step 12 is performed according to instructions from the host device 1 (step 13). Note that at this time, information including cylinder and track (head) numbers may actually be written/read, but the
The information may be converted in the same manner as in step 12.

As explained above, two magnetic disk drives 3.4
can be presented to the host device 1 as one expanded virtual magnetic disk device. Although this embodiment shows the case of two magnetic disk devices, if the magnetic disk control device can recognize the number of disk devices, three or more magnetic disk devices can be combined into one virtual magnetic disk device in the same way. It is also easy to show off.

〔Effect of the invention〕

As described above, the present invention has the effect of reducing the control from a host device, especially the file management function by software, by making a plurality of magnetic disk devices of the same type appear as one virtual magnetic disk device.

[Brief explanation of the drawing]

FIG. 1 is a configuration diagram of an embodiment of a magnetic disk device subsystem to which the magnetic disk access method of the present invention is applied;
FIG. 2 is a flowchart showing the control of the magnetic disk controller 2, FIG. 3 is a track map of the magnetic disk device 3.4, and FIG. 4 is a configuration diagram of a conventional example of the magnetic disk device subsystem. 1.21--Host device, 2.22--Magnetic disk control device, 3.4.23.
24--Magnetic disk device, 11-14--Operation step of magnetic disk control device 2.

Claims (1)

[Claims] 1. In a magnetic disk device subsystem consisting of a plurality of magnetic disk devices and a magnetic disk control device connected to a host device and controlling these magnetic disk devices, If consecutive track numbers are assigned to the cylinders and the plurality of magnetic disk devices are presented as one virtual magnetic disk device to the higher-level device, and the magnetic disk control device specifies the track number by the higher-level device, A magnetic disk access method that performs seek address conversion to access the corresponding track of a magnetic disk device.