Data processing: database and file management or data structures – Database design – Data structure types
Reexamination Certificate
1998-06-29
2002-09-17
Von Buhr, Maria N. (Department: 2125)
Data processing: database and file management or data structures
Database design
Data structure types
C709S241000
Reexamination Certificate
active
06453316
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a file system, and more specifically, it relates to a file system handling reading/writing of multimedia data such as pictures, sounds and animation requiring real-time properties.
2. Description of the Background Art
A file system employed in a conventional computer has mainly handled text data. According to “Design of UNIX Kernel” (written by Maurice J. Bach/translated by Fumi Sakamoto, Yoshikatsu Tada and Jun Murai; Kyoritsu Shuppan Kabushiki Kaisha), for example, a file is opened with an open system call for reading or writing the content of the file with a system call such as read or write in case of reading or writing data from or in the file in the UNIX file system.
Such file systems include video servers handling digitized video data, for example. Such video servers include that having a structure of connecting a plurality of storage units storing video data with each other by an exchange unit, as described in Japanese Patent Laying-Open gazette No. 07-107425 titled “Video server”. A video regeneration procedure in such a video server is described in ISO/IEC Standard 13818-6 (Committee Draft). According to this Committee Draft, the video server completes preparation for continuous regeneration of pictures when a user transmits “Directory Open” to the video server, while the video server starts transmission of video data to the user when the user transmits “DSM Stream Play” or “DSM Pause Resume”. In order to stop supply of the video data, the user transmits “DSM Stream Pause” to the video server.
In the conventional file system such as UNIX, however, the waiting time for reading is increased on the user side when a number of accesses are simultaneously made by users. The waiting time for a user issuing a read command for completely receiving data is unpredictable due to influence exerted by the situation of accesses from other users. Particularly in the file system such as the video server managing data such as pictures and sounds requiring temporal continuity so that each user reads a part of the data every constant time for regenerating the data in his terminal, it is necessary to reliably acquire the data within the constant time, while the conventional file system cannot cope with this. In relation to the data such as video data requiring temporal continuity, therefore, the user must previously acquire long data for regenerating pictures after acquiring all data. In this case, the user must hold a mass storage unit which can store long data, and a long waiting time is required for starting regeneration of pictures.
SUMMARY OF THE INVENTION
Therefore, an object of the present invention is to provide a file system which can provide data to a request from a user in a quick response time, and support users requiring various regeneration speeds.
The present invention has the following characteristics to attain the above object.
The first aspect is a file system for reading or writing data from or in a storage unit for storing data in response to a request from an exterior, which comprises:
a resource management part for managing the maximum value of read or write handling capacity and a used quantity of the handling capacity, and
the resource management part is adapted:
to receive a get resource message previously requiring assurance of a necessary band in case of reading or writing the data;
to determine whether or not the band required by the get resource message can be ensured on a basis of the maximum value and the used quantity of the handling capacity when the get resource message is received; and
to update and store the used quantity if the required band can be ensured as a result of the determination.
According to the first aspect, as hereinabove described, the band in the file system is ensured when the get resource message is received, whereby it is possible to guarantee delay quality as to reading or writing of files. Further, it is possible to efficiently utilize resources in the file system without ensuring a useless band, by implementing reading or writing of a plurality of files through the ensured band.
The second aspect is characterized in that, in the first aspect,
information indicating a necessary band width is given to the get resource message as a parameter.
The third aspect is characterized in that, in the second aspect,
the information, which is the parameter of the get resource message, indicating the necessary band width represents an interval for reading/writing a data block having a fixed length from/in the storage unit.
The fourth aspect is characterized in that, in the first aspect,
the band width which is ensured in accordance with the request by the get resource message is previously stored in the resource management part.
The fifth aspect is characterized in that, in the fourth aspect,
information for identifying whether the get resource message is for reading or writing is given to the get resource message, and
the resource management part stores two types of band quantities for reading and writing as band quantities which are ensured in accordance with the request by the get resource message.
The sixth aspect is characterized in that, in the first aspect,
a first delay time from a request for reading data up to start of transmission of the data is given to the get resource message as a parameter, and
the resource management is adapted:
to previously store a minimum value of a delay time which is warrantable by the file system;
to compare the first delay time with the minimum value when the get resource message is received; and
to ensure no band if the first delay time is shorter than the minimum value as a result of the comparison.
The seventh aspect is characterized in that,
the sixth aspect further comprises a declared value management part for checking a parameter which is given to a message arriving from the exterior, and
the declared value management part is adapted:
to receive a read block message which is provided with a second delay time up to start of transmission of read data as the parameter in case of performing data reading;
to compare the second delay time with the first delay time when the read block message is received; and
to decide transmission of a violation notice to a transmitter of the read block message when the second delay time is determined to be shorter as a result of the comparison.
The eighth aspect is characterized in that,
the first aspect further comprises a declared value management part for checking a parameter which is given to a message arriving from the exterior, and
the declared value management part is adapted:
to store a minimum value of a delay time which is warrantable by the file system;
to receive a read block message which is provided with a second delay time up to start of transmission of read data as the parameter in case of performing data reading;
to compare the second delay time with the minimum time when the read block message is received; and
to decide transmission of a violation notice to a transmitter of the read block message when the second delay time is determined to be shorter as a result of the comparison.
The ninth aspect is characterized in that, in the first aspect,
the get resource message is provided with a delay time up to start of transmission of data from a read request as a parameter, and
the resource management part is adapted:
to calculate a band width which is necessary for satisfying the delay time when the get resource message is received; and
to compare the band width which is obtained as a result of the calculation with the band width to be ensured in accordance with the request by the get resource message, for determining whether or not the larger band width can be ensured.
According to the ninth aspect, as hereinabove described, a determination is made as to whether or not the larger band can be ensured in the band satisfying the delay time declared by the get resource message and the band to be ensured in accordance with the request by the get resource message to allocate t
Doi Shinzo
Ito Yukiko
Karibe Tomoyuki
Kokado Takeshi
Tamai Masaaki
Matsushita Electric - Industrial Co., Ltd.
Von Buhr Maria N.
Wenderoth , Lind & Ponack, L.L.P.
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