JP2009016010A - File management method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a file management method which can read media of UDF 2.01 or earlier, and is compliant with the UDF 2.50 standard. <P>SOLUTION: The file management method uses a file system having a metadata area for gathering and arranging file system management information. In the file management method, a logical address in the metadata area is converted into a logical address in a physical partition including the metadata area, and files and the file system management information are recorded in accordance with the converted logical address. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to a file management method, and more particularly to a file management method that can be read even in file systems of different versions.

  In a file system that manages information recorded on a recording medium, a difference may occur in a file access method due to a difference in the file system, a difference in the version of the file system, or the like.

  As a result, even if one system can read the recorded information, another system cannot read the information.

  As a countermeasure, Patent Document 1 discloses a technique for acquiring an information recording status by a program in a computer that controls a playback apparatus even on an information recording medium recorded in a format different from a recognizable format. In this way, compatibility is improved, for example, the position of management information can be grasped and read.

  There are various file systems, but the technology to record files on large-capacity recording media has begun to spread, and in response, various recording formats for recording files on large-capacity recording media are proposed. Has been made.

For example, UDF (Universal Disk Format) which is a file system adopted for DVD (Digital Versatile Disc), Blu-ray Disc, HD DVD, and the like is one of them.
JP 2003-223759 A Universal Disk Format Specification Revision 2.01 March 15,2000 Optical Storage Technology Association Universal Disk Format Specification Revision 2.50 April 30,2003 Optical Storage Technology Association

  However, there are various versions of UDF, and the specifications differ between the versions, and compatibility between the lower versions is possible between the versions, but not compatibility with the higher versions.

  For example, in UDF2.50, file system information is collectively arranged in an area called a metadata partition, and a function for managing file system information by a logical address in the metadata partition is added. The metadata partition is also called a metadata area.

  However, since there is no metadata partition in UDF2.01 and earlier versions, there is no compatibility between UDF2.50 and earlier versions (Non-Patent Documents 1 and 2).

  That is, for example, a PC (Personal Computer) or a playback device that supports only UDF 2.01 cannot read an optical disc recorded based on the UDF 2.50 standard.

  Therefore, an object of the present invention is to provide a file management method that can be read by UDF2.01 or earlier and conforms to the UDF2.50 standard.

  As a means for solving the above problems, the present invention provides a file management method using a file system having a metadata area for collecting and arranging file system management information, wherein a logical address in the metadata area is The information is converted into a logical address in a physical partition including a metadata area, and a file and file system management information are recorded based on the converted logical address.

  According to the present invention, it is possible to access a disc recorded based on UDF version 2.50 or later in a file system of UDF 2.01 or earlier.

  DESCRIPTION OF THE PREFERRED EMBODIMENTS The best mode for carrying out the present invention will be described below with reference to the accompanying drawings.

  FIG. 2 is a table showing a configuration example of file system management information of a DVD-RW disc recorded based on the UDF 2.50 standard.

  In FIG. 2, a portion surrounded by a double line is a physical partition, and a portion surrounded by a thick line in the physical partition is a metadata partition.

  Hereinafter, the relative position in the physical partition is expressed as LBN (Logical Block Number), and the relative position in the metadata partition is expressed as MBN (Metadata Block Number).

  First, a procedure until the UDF file system reads the substance of the target file in the disc recorded based on the UDF 2.50 standard will be described with reference to FIG.

  In the UDF file system, file system management information, directories, and logical addresses representing file positions are represented by logical sector numbers (LSN). Based on the LSN, data size, and partition number, file system management information, directory, and file are accessed.

  Hereinafter, in FIG. 2, an area from LSN 0 to Last LSN is referred to as a user data area, and a position based on the head of this area is referred to as LSN.

  As an actual procedure, Anchor Volume Descriptor Pointer (hereinafter referred to as AVDP) is first read.

  In FIG. 2, portions corresponding to LSN 256, Last LSN-256, and Last LSN correspond to AVDP. However, unless there is a read error, an AVDP having LSN 256 is normally read.

  In the AVDP, the positions of two primary volume descriptors (hereinafter referred to as PVD) (LSNs in FIGS. 2 corresponding to 32 and 64) are recorded. As long as there is no read error, the PVD with the LSN of 32 in the Main Volume Descriptor Sequence is normally read.

  Thereafter, management information recorded in successive sectors from the PVD is sequentially read, but the description of items that are not directly related to the description of the file access procedure is omitted.

  Three things are necessary to access the file entity:

(1) Physical partition start position recorded in the Partition Descriptor (hereinafter referred to as PD) (2) File Set Descriptor (hereinafter referred to as FSD) recorded in the Logical Volume Descriptor (hereinafter referred to as LVD) Position (3) Extended File Entry (hereinafter referred to as EFE) indicating the start position of the metadata partition
Here, the physical partition start position in the PD is recorded in LSN, but the FSD position is recorded in MBN, and the EFE indicating the start position of the metadata partition is recorded in LBN.

  Before accessing a file, you need to access the root directory.

  In UDF, a File Identifier Descriptor (hereinafter referred to as FID) corresponds to a directory body.

  In the above FSD, the position of EFE (root) indicating the position of FID (root) of the root directory is recorded in MBN.

  In other words, to access the root directory, search and access the following two items. It is an EFE (Metadata File) in the physical partition based on the start position of the physical partition found from the PD and the position of the EFE (Metadata File) found from the LVD.

  Next, the start position of the metadata partition recorded in the EFE (Metadata File) and the FSD recorded in the metadata partition are searched from the position of the FSD determined from the LVD and accessed.

  Since the FSD indicates the position of the EFE (root) and the EFE (root) indicates the position of the FID (root) of the root directory, access is made sequentially to reach the root directory.

  When accessing the target file from the root directory, first, the FID (root) of the root directory is referred to.

  In the FID, the names of all directory files existing immediately under the directory and the EFE positions indicating the actual positions of the directory files are recorded.

  The actual position here is the FID for a directory, and the file body for a file. One FID always corresponds to one directory.

  If the target file exists at a deep position in the directory hierarchy, the EFE and FID of the directory are sequentially traced. Access is made to the FID of the directory in which the target file exists, and the file body is accessed from the FID through the EFE.

  For example, in the case of a directory hierarchy as shown in FIG. To access file C, first access the EFE and FID of the root directory, the EFE and FID of directory A, the EFE and FID of directory B, the FID of directory B, and then the EFE of file C, and finally the target file A certain file C is reached.

  FIG. 3 summarizes the management information reading procedure until the target file is accessed.

  The file access means for the disk recorded in the conventional UDF 2.50 standard has been described above.

  However, when trying to read a disk recorded by such a conventional method with a file system prior to UDF 2.01, the position of the FSD recorded in MBN is interpreted as LBN and access is attempted. For this reason, the recording position of the FSD cannot be specified and the disk cannot be read.

  Therefore, all the positions of the file system management information recorded in MBN are converted to LBN and recorded in LBN.

  This makes it possible to read a disc recorded in the UDF 2.50 standard even in a file system of a version prior to UDF 2.01.

  FIG. 5 is a block diagram showing an example of the configuration of a recording / reproducing apparatus that creates a recording medium capable of realizing the file management method.

  In FIG. 5, 1 is a recording medium capable of recording / reproducing data, 2 is a drive device that performs recording / reproduction processing on the recording medium 1, and 3 is a device control unit that controls recording / reproduction of the drive device 2.

  A microcomputer 4 transmits a recording / reproduction request to the apparatus control unit 3, and also transmits a conversion request to the sector number conversion unit 5 that converts MBN to LBN as necessary.

  As a procedure for creating a recording medium for realizing the proposed method, first, the microcomputer 4 transmits a sector number that needs to be converted from MBN to LBN to the sector number conversion unit 5.

  Then, the sector number conversion unit 5 receiving it converts MBN to LBN and transmits the converted sector number to the device control unit 3.

  Upon receiving the converted sector number, the device control unit 3 controls the drive device 2 to record on the recording medium with the converted sector number, and the drive device 2 writes to the recording medium 1 by the recording method based on the proposed method. I do.

  Hereinafter, UDF management information that is recorded in MBN and needs to be converted into LBN and recorded will be described.

  First, it is necessary to convert and set the position of the FSD whose position is indicated by the MBN in the LVD to the LBN.

  Each piece of management information in the UDF file system includes header information called a descriptor tag, and the file system recognizes the type of management information.

  A parameter called Tag Location in the Descriptor Tag records the position of the management information itself. In the conventional method, this Tag Location is recorded in LBN if it is in a physical partition, and MBN if it is in a metadata partition.

  For this reason, all tag locations of management information existing in the metadata partition are converted into LBN and recorded.

  As a specific method for converting from MBN to LBN, as shown in FIG. 1, LBN is calculated by adding the value of MBN to the start position of the metadata partition recorded in LBN found from EFE (Metadata File). To do. MBN corresponds to N in FIG.

  Examples of management information recorded in the metadata partition include FSD, Terminating Descriptor, EFE (or File Entry), and FID.

  In addition, UDF uses a parameter called Allocation Descriptor (hereinafter referred to as AD) in management information when pointing to other management information or the position of a file body in some management information.

  In addition to the position and size of the target data, this AD includes a parameter called Partition Reference Number indicating the partition number. This describes to which partition other management information and files belong.

  The Partition Reference Number is set to 0 when indicating the management information / file existing in the normal physical partition, and 1 when indicating the metadata partition.

  In order to set all MBNs to LBN, all of the Partition Reference Numbers in AD are set to 0.

  EFE (Metadata File) also contains the size of the metadata partition. Therefore, it is possible to determine whether certain management information is in the metadata partition based on the information on the start position and size of the metadata partition.

  The flow of processing in the proposed method is shown in FIG. Hereinafter, the flow of processing will be described with reference to FIG.

  First, before recording on a recording medium, it is confirmed whether the version is UDF 2.50 or later (step S1).

  If the version is not UDF 2.50 or later (step S1 / No), recording on the recording medium is performed without converting the sector number (step S7).

  If the version is UDF 2.50 or later (step S1 / Yes), it is confirmed in step S2 whether the start position / size of the metadata partition has already been acquired. If not acquired (step S2 / No), the start position / size of the metadata partition is acquired (step S3).

  Next, whether the management information is in the metadata partition is checked by the above-described method (step S4). If the management information is in the metadata partition, the sector number is converted from MBN to LBN (step S5).

  In addition, the Partition Reference Number is set in the physical partition (step S6).

  Steps S4 to S6 are repeated as many times as the number of management information in the metadata partition, and after all the sector numbers have been converted, recording is actually performed on the recording medium (step S7).

  The UDF 2.50 standard does not stipulate that the position of management information must be recorded at the relative position of the metadata partition, so the above recording method also conforms to the UDF 2.50 standard.

  In UDF 2.50, a mirror of a metadata partition called a metadata mirror file may be optionally recorded for backup.

  If the management information positions of various file systems are recorded in the MBN as in the prior art, a copy of the management information in the metadata partition may be recorded as it is.

  However, when MBN is recorded as LBN, the Tag Location value in the Descriptor Tag and the position (AD) of other management information pointed to by the management information in the metadata partition are different from the actual ones.

  For this reason, when recording a mirror file, it is necessary to replace the Tag Location and AD of each management information of the metadata partition once stored in the memory with the LBN in which the mirror file is recorded.

  However, the mirror file is recorded only at the time of finalizing the disk, and generally the finalizing processing time which takes several minutes is increased to several seconds for rewriting the memory.

  In the above, the UDF file system has been described as an example, but the present invention may be applied to other file systems having an area such as a metadata partition.

  The present invention is applicable to a file system that manages information recorded on a recording medium.

It is a figure for demonstrating the file management method in embodiment of this invention. It is a figure for demonstrating the structure of the management information of the general file system recorded by UDF2.50 specification. It is a figure for demonstrating the procedure at the time of a UDF file system accessing the target file. It is a figure for demonstrating the access method to a target file. It is a block diagram which shows the outline of the apparatus which performs recording to the medium for implement | achieving the file management method in embodiment of this invention. It is a flowchart which shows the process at the time of performing sector number conversion in embodiment of this invention.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Recording medium 2 Drive apparatus 3 Apparatus control part 4 Microcomputer 5 Sector number conversion part

Claims (4)

In a file management method using a file system having a metadata area for collecting and arranging file system management information,
A logical address in the metadata area is converted into a logical address in a physical partition including the metadata area;
A file management method comprising recording a file and file system management information based on the converted logical address. 2. The file management method according to claim 1, wherein the physical partition records user data and file system management information for managing the user data. 2. The file management method according to claim 1, wherein the recording position of the file is represented by a partition number, a position from the beginning of the partition, and a data size. 2. The file management method according to claim 1, wherein the file system is UDF version 2.50 or higher.