Electrical computers and digital processing systems: memory – Storage accessing and control – Specific memory composition
Reexamination Certificate
2001-07-31
2003-03-18
Yoo, Do Hyun (Department: 2187)
Electrical computers and digital processing systems: memory
Storage accessing and control
Specific memory composition
C711S111000, C711S113000, C711S114000, C711S137000, C714S006130, C714S049000, C360S051000, C360S053000, C360S062000
Reexamination Certificate
active
06535953
ABSTRACT:
TECHNICAL FIELD
The present invention relates to a magnetic disc apparatus and, more particularly, to magnetic disc apparatus which accesses plurality of large capacity successive data, and a disc access method for the magnetic disc apparatus. Further, the invention relates to a recording medium having recorded a program for a disc access control for a magnetic disc apparatus.
BACKGROUND ART
In computer systems which perform control and administration of OA apparatuses or industrial apparatuses, accompanying with an increase in handling information data, a large capacity memory has been required for recording those information data. As a large capacity memory device satisfying such requirements, a magnetic disc apparatus employing a magnetic disc as recording medium has been widely used.
By the way, in transmitting files between a magnetic disc apparatus and a host apparatus connected externally of the magnetic disc apparatus, it is a basic operation that the magnetic disc apparatus commences access to the magnetic disc in the magnetic disc apparatus after receiving a command issued from the host apparatus.
When a command and a command parameter are transmitted at the same time from the host apparatus, the magnetic disc apparatus calculates at which position on the magnetic disc the data the host apparatus has required an access physically exists, makes the head seek a track on the magnetic disc in the magnetic disc apparatus according to the calculated result, thereby to perform reading out or writing in from/into the data required by the host apparatus.
Hereinafter, such a magnetic disc apparatus will be described, particularly on the operation thereof with reference to drawings.
FIG. 7
is a diagram illustrating an operation of the magnetic disc apparatus, and particularly, a processing performed on the magnetic disc, when the host apparatus accesses two large capacity successive data located apart from each other in the magnetic disc apparatus at the same time.
In
FIG. 7
, file (m−1)′, m, m′ and m+1constitute a part of large capacity successive data A, and file (n−1)′, n, n′ and n+1 constitute a part of large capacity successive data B.
Further, file (m−1)′ and file m locate on track M, file m′ and file m+1 locate on track M+1, file (n−1) and file n locate on track N, and file n′ and file n+1 locate on track N+1. Each file has the size that is equal to the data length which is handled at one time command by the host apparatus.
While when the host apparatus accesses a large capacity successive data, the host apparatus has only to issue commands for accessing files in chronological order of the successive files, when the host apparatus accesses two large capacity successive data at the same time, the host apparatus has to issue commands for accessing respective files in the large capacity successive data A and commands for accessing respective files in the large capacity successive data B, alternately, at a constant period (band). These commands are shown in FIG.
8
.
In this case, as shown in
FIG. 8
, the magnetic disc apparatus interprets the content of the command each time when it receives the issued command, and calculates the positional information at which physical location the demanded data locates physically on the magnetic disc from the command parameter thereby to carry out accessing to the data on the magnetic disc.
That is, in the magnetic disc apparatus, accessing to the large capacity successive data A and accessing to the large capacity successive data B are carried out alternately and successively.
To be concrete, as shown in
FIG. 7
, accessing to the magnetic disc is carried out in the order of access
1
to the file m and the file m′, seek
1
for executing access
2
to the file n and the file n′, the access
2
to the file n and the file n′, seek
2
for executing access
3
to the file m+1, the access
3
to the file m+1, seek
3
for executing access
4
to the file n+1, and the access
4
to the file n+1.
However, in the conventional magnetic disc apparatus, though accessing to files respectively constituting each of two large capacity successive data are carried out alternatively, and it is possible to predict a physical location from which accessing to data on the optical disc is started, it is impossible to start accessing to respective files until a command is issued from the host apparatus. In other words, the magnetic disc should arise an idle state in which nothing is performed to the magnetic disc during a period from the completion of an access to a file up to starting of a seek for carrying out an access to next file.
That is, when the host apparatus accesses a plurality of large capacity successive data at the same time, even though there is a high possibility of performing an access to data whose access starting position on the magnetic disc can be predicted, the magnetic disc apparatus stops accessing to the magnetic disc and enters a waiting state (the idle state) after completing the accessing to the file now being processed, and the idle state continues until a next command is received. When receiving the next command, the magnetic disc apparatus interprets the received command, calculates location information from the command parameter, and seeks the track in which data is present, and thereafter, starts accessing to the data.
In this way, when the host apparatus accesses a plurality of large capacity successive data at the same time, there should arise an idle state where no access is performed to the magnetic disc, thereby no improvement in the data transfer efficiency.
The present invention is directed to solve the above described problem, and has for its object to provide a magnetic disc apparatus which does not reduce the data transfer efficiency between the magnetic disc and a buffer memory even when accessing to plural systems of large capacity successive data are carried out, to provide a disc access method for the magnetic disc apparatus, which enables the above-described disc access, and further, to provide a recording medium having recorded a disc access control program for a magnetic disc apparatus.
DISCLOSURE OF THE INVENTION
According to a first aspect of the present invention, there is provided a magnetic disc apparatus which can read out or write into various kinds of information data by accessing a magnetic disc employed as a recording medium, wherein when a host apparatus connected externally to the magnetic disc apparatus, performs an access to each of plural systems constituting large capacity successive data, which systems are located apart from each other in the magnetic disc apparatus, the magnetic disc apparatus stores a record of commands at the same time when the host apparatus issues commands for accessing the respective systems to the magnetic disc apparatus, compares a new received command with the stored record of commands to detect continuity of commands against the respective systems every time when it receives a new command issued from the host apparatus, and preserves location information indicating physical location on the magnetic disc at which data to be accessed for each of the plural systems locate, and in which apparatus a system preserving the location information starts data accessing to the magnetic disc by employing the location information when the magnetic disc apparatus receives a command issued from the host apparatus.
According to the present invention, while accessing large capacity successive data on a magnetic disc, the time required for interpreting a command after receiving the command can be reduced, as well as the time from the completion of an access to one system to the start of an access to next system can be shortened, thereby the data transmission efficiency is enhanced.
According to a second aspect of the present invention, there is provided a magnetic disc apparatus which can read out or write into various kinds of information data by ac
Dinh Ngoc V
Matsushita Electric - Industrial Co., Ltd.
Yoo Do Hyun
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