Error detection/correction and fault detection/recovery – Data processing system error or fault handling – Reliability and availability
Reexamination Certificate
1999-07-26
2004-08-24
Le, Dieu-Minh (Department: 2114)
Error detection/correction and fault detection/recovery
Data processing system error or fault handling
Reliability and availability
C369S047140
Reexamination Certificate
active
06782488
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to an optical recording medium which allows rewriting, and more particularly to a method and apparatus of recording data in the optical recording medium, wherein defect areas can be managed.
2. Description of Related Art
An optical storage medium is generally divided into a read only memory (ROM), a write once read many (WORM) memory into which data can be written one time, and rewritable memories into which data can be written several times. Rewritable optical storage mediums, i.e. optical discs, include rewritable compact discs (CD-RW) and rewritable digital versatile discs (DVD-RW, DVD-RAM, DVD+RW).
The operations of writing and playing back data in a rewritable optical disc may be repeated. This repeated process alters the ratio of storage layers for recording data into the optical disc from the initial ratio. Thus, the optical discs lose its characteristics and generate an error during recording/playback. This degradation is indicated as a defective area at the time of formatting, recording on or playing back from an optical storage medium. Also, defective areas of a rewritable optical disc may be caused by a scratch on its surface, particles of dirt and dust, or errors during manufacture. Therefore, in order to prevent writing into or reading out of the defective area, management of such defective areas is necessary.
FIG. 1
shows a defect management area (DMA) in a lead-in area and a lead-out area of the optical disc to manage a defect area. Particularly, the data area is divided into a plurality of zones for the defect area management, where each zone is further divided into a user area and a spare area. The user area is where data actually written and the spare area is used when a defect occurs in the user area.
There are four DMAs in one disc, e.g. DVD-RAM, two of which exist in the lead-in area and two exist in the lead-out area. Because managing defective areas is important, the same contents are repeatedly recorded in all four DMAs to protect the data. Each DMA comprises two blocks of 32 sectors, where one block comprises 16 sectors. The first block of the DMA, called a DDS/PDL block, includes a disc definition structure (DDS) and a primary defect list (PDL). The second block of the DMA, called an SDL block, includes a secondary defect list (SDL). The PDL corresponds to a primary defect data storage and the SDL corresponds to a secondary defect data storage.
The PDL generally stores entries of defective sectors caused during the manufacture of the disc or identified when formatting a disc, namely initializing and re-initializing a disc. Each entry is composed of an entry type and a sector number corresponding to a defective sector. The SDL lists defective areas in block units, thereby storing entries of defective blocks occurring after formatting or defective blocks which could not be stored in the PDL during the formatting. As shown in
FIG. 2
, each SDL entry has an area for storing a sector number of the first sector of a block having defective sectors, an area for storing a sector number of the first sector of a block replacing the defective block, and reserved areas.
Also, each SDL entry is assigned a value of 1 bit for forced reassignment marking (FRM). A FRM bit value of 0 indicates that a replacement block is assigned and that the assigned block does not have a defect. A FRM bit value of 1 indicates that a replacement block has not been assigned or that the assigned replacement block has a defect. Thus, to record data in a defective block listed as a SDL entry, a new replacement block must be found to record the data. Accordingly, defective areas, i.e. defective sectors or defective blocks, within the data area are replaced with normal or non-defective sectors or blocks by a slipping replacement algorithm and a linear replacement algorithm.
The slipping replacement is utilized when a defective area or sector is recorded in the PDL. As shown in
FIG. 3A
, if defective sectors m and n, corresponding to sectors in the user area, are recorded in the PDL, such defective sectors are skipped to the next available sector. By replacing the defective sectors by subsequent sectors, data is written to a normal sector. As a result, the user area into which data is written slips and occupies the spare area in the amount equivalent to the skipped defective sectors.
The linear replacement is utilized when a defective block is recorded in the SDL or when a defective block is found during playback. As shown in
FIG. 3B
, if defective blocks m and n, corresponding to blocks in either the user or spare area, are recorded on the SDL, such defective blocks are replaced by normal blocks in the spare area and the data to be recorded in the defective block are recorded in an assigned spare area. To achieve the replacement, a physical sector number (PSN) assigned to a defective block remains, while a logical sector number (LSN) is moved to the replacement block along with the data to be recorded. Linear replacement is effective for non real-time processing of data. For convenience, a data which does not require real time processing is hereinafter called a personal computer (PC)-data.
If a replacement block listed in the SDL is found to be defective, a direct pointer method is applied to the SDL listing. According to the direct pointer method, the defective replacement block is replaced with a new replacement block and the SDL entry of the defective replacement block is modified into a sector number of the first sector of the new replacement block.
FIG. 4A
shows a procedure to manage a defective block found while writing or reading data into or from the user area. FIGS.
4
B~
4
D show embodiments of SDL entries generated according to the linear replacement algorithm. Each SDL entry has, in order, a FRM, a sector number of the first sector of the defective block, and a sector number of the first sector of the replacement block.
For example, if the SDL entry is (1, blkA, 0) as shown in
FIG. 4B
, a defective block has been newly found during the reproduction and is listed in the SDL. This entry indicates that a defect occurs in block blkA and that there is no replacement block. The SDL entry is used to prevent data from being written into the defective block in the next recording. Thus, during the next recording, the defective block blkA is assigned a replacement block according to the linear replacement.
An SDL entry of (0, blkA, blkE), shown in
FIG. 4C
, indicates that the assigned replacement block blkE has no defect and data to be written into the defective block bikA in the user area is written into the replacement block blkE in the spare area. An SDL entry of (1, blkA, blkE) shown in
FIG. 4D
, indicates that a defect occurs in the replacement block blkE of the spare area which replaced the defective block blkA of the user area. In such case, a new replacement block is assigned according to the direct pointer method.
FIG. 5
is a partial diagram of an optical disc recording/playback (R/P) device relating to the recording operation. The optical disc (R/P) device includes an optical pickup to write data into and playback data from the optical disc; a servo unit controlling the optical pickup to maintain a certain distance between an object lens of the optical pickup and the optical disc, and to maintain a constant track; a data processor either processing and transferring the input data to the optical pickup, or receiving and processing the data reproduced through the optical pickup; an interface transmitting and receiving data to and from an external host; and a micro processor controlling the components. The interface of the optical disc R/P apparatus is coupled to a host such as a PC, and communicates commands and data with the host.
If there is data to be recorded in an optical disc R/P apparatus, the host sends a recording command to the optical disc R/P apparatus. The recording command comprises a logical block address (LBA) designating a recording location and a transfer length indic
Jeong Kyu Hwa
Lee Myong-Gu
Park Yong Cheol
Shin Jong In
Birch & Stewart Kolasch & Birch, LLP
Le Dieu-Minh
LG Electronics Inc.
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