Electrical computers and digital processing systems: memory – Storage accessing and control – Memory configuring
Reexamination Certificate
1998-02-25
2001-02-06
Cabeca, John W. (Department: 2752)
Electrical computers and digital processing systems: memory
Storage accessing and control
Memory configuring
C711S112000, C711S171000, C711S172000, C707S793000
Reexamination Certificate
active
06185665
ABSTRACT:
FIELD OF THE INVENTION
The present invention relates to a file management apparatus, a file management method, and a recording medium containing a file management program, in an information processor using a media exchange type storage device which is represented by an optical disk library, as an external storage device and, more particularly, to those by which a file that is readable in real time and with less exchange of optical disks can be created.
BACKGROUND OF THE INVENTION
As prior art methods of using a media exchange type storage device represented by an optical disk library as an external storage device, there have been known two methods; a method which is basically equivalent to a method of utilizing external optical disk drives and has a means for automatically mounting an optical disk (storage medium) to be accessed, in an optical disk drive (data access device) as the only feature, and a method disclosed by Japanese Published Patent Application No. Hei. 7-93110, in which a plurality of optical disks are virtually treated as a single storage device.
In both of the methods, a prior art data writing process to an external storage device is used for data writing to an optical disk serving as a storage medium.
The prior art data writing process to an external storage device is disclosed in detail by Japanese Published Patent Application No. Hei. 4-225441.
As methods for locating file data on a storage medium, there are a data block allocation method and a continuous region allocation method.
The data block allocation method comprises dividing a storage medium into data blocks of fixed capacity, generally, a few hundreds of bytes to a few kilobytes, and writing data to the storage medium while successively allocating unused data blocks to the data. In this data block allocation method, when data of one file are written to plural data blocks, the positional relationships between the used data blocks are not considered. In this method, storage positions of a file are generally managed as a list of data block numbers (data block addresses) assigned to respective data blocks.
Meanwhile, in the continuous region allocation method, storage positions of a file are managed according to a top address and a length of data.
In the data block allocation method, since storage regions for respective blocks are allocated even when file writing and partial erasure are repeated, the storage regions can be effectively utilized. However, data of a file must be extracted from data blocks which are disorderedly located in several parts of a storage medium, so that it takes time to read the file.
In the continuous region allocation method, since data of a file are located continuously, file reading can be carried out at high speed. However, when file writing and partial erasure are repeated, continuous unused storage regions enough for file storage are not found although many unused storage regions remain, so that many useless storage regions are produced.
Conventiornally, it has been taken for granted that the continuous region allocation method is used for an optical disk, in order to read multimedia data, such as voice data and moving picture data, at high speed and perform processing in real time. In recent years, however, even when the data block allocation method is used for an optical disk, an improvement of reading performance has made processing in real time possible.
Further, effective use of storage regions of an optical disk of mass storage has been regarded as important, and the data block allocation method has been generally used for an optical disk.
A description is given of a data block allocation method in a prior art information processor in which a plurality of optical disks in an optical disk library are virtually treated as a single storage device, with reference to
FIGS. 1
,
2
,
3
,
4
and
5
(
a
) and
5
(
b
) which show component parts common with a file management apparatus according to a first embodiment of the present invention, and
FIG. 24
which shows the operation of the prior art information processor.
FIG. 1
is a block diagram illustrating a general construction of an information processor in which a plurality of optical disks in an optical disk library are virtually treated as a single storage device.
In
FIG. 1
, an information processor
1
has an optical disk library
300
as an external storage device, and includes a file management apparatus
2
. The file management apparatus
2
comprises a file managment unit
100
and a disk management unit
200
.
The file management unit
100
comprises a data block management unit
110
for managing data blocks and a data block allocation unit
120
for allocating data blocks to files. The data block management unit
110
has a data block management table
111
illustrated in
FIG. 2
, and the data block allocation unit
120
has a file management table
121
illustrated in FIG.
3
.
The disk management unit
200
comprises a virtual disk management unit
210
and an optical disk library control unit
220
. The virtual disk management unit
210
has a data block corresponding table
211
illustrated in
FIG. 4
, and the optical disk library control unit
220
has an optical disk management table
221
illustrated in FIGS.
5
(
a
) and
5
(
b
).
The optical disk library
300
includes optical disk drives D
0
to D
3
serving as data access devices, optical disks M
0
to M
9
serving as storage media, and an optical disk exchanging device
310
for mounting the optical disks in the optical disk drives D
0
to D
3
according to requests from the outside.
FIG. 24
is a flow chart showing the operation of the information processor for virtually treating the plurality of optical disks in the optical disk library as a single storage device.
A description is given of the operation of the information processor thus constructed, with reference to FIG.
24
.
When the file management unit
100
in the file management apparatus
2
receives a writing request of a file, at step S
1201
, the data block management unit
110
examines whether unused data blocks are present or not, using the data block management table
111
.
When no unused data blocks are present, no file can be stored. Therefore, the writing process is completed as a file writing error due to shortage of the capacity (step S
1207
).
When the unused data blocks are present, step S
1202
is executed, The data block management unit
110
selects one unused data block from the data block management table
111
, and updates the data block management table
111
, i.e., changes the use flag of the selected data block to “used”. For example, the data block with the number “2” is selected from the data block management table
111
shown in
FIG. 2
, and the use flag of the data block with the number “2” is changed to “used”.
Then, at step S
1203
, the data block allocation unit
120
allocates the selected data block as a data storage block for the file to be written, and updates the file management table
121
. For example, when the file
3
is additionally written in the file management table
121
shown in
FIG. 3
, the data block number “2” of the data block selected at step S
1202
is added to the used data block number list of the file
3
, and the used data block number list of the file
3
is changed to “4, 2”. When a new file which has been not recorded in the file management table
121
, for example, a file
10
, is written, a new field for the file
10
is created in the file management table
121
, and the used data block number list of the field is made “2”.
Subsequently, at step S
1204
, the file management unit
100
instructs the disk management unit
200
to write the file data to the allocated data block. When the disk management unit
200
receives this instruction, using the data block corresponding table
211
, the disk management unit
200
obtains an optical disk number of an optical disk having the data block to which the file data is to be written, and calculates a real data block number of the data block on the optical disk, by the virtual
Miyazaki Masaya
Owada Kiyoshi
Anderson Matthew D.
Cabeca John W.
Matsushita Electric - Industrial Co., Ltd.
Parkhurst & Wendel L.L.P
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