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Directory Structure and Data Layout for the Efficient Writing and Reading of Data on 12" Write Once Read Many Optical Disk MEDIA

IP.com Disclosure Number: IPCOM000107876D
Original Publication Date: 1992-Mar-01
Included in the Prior Art Database: 2005-Mar-22
Document File: 8 page(s) / 370K

Publishing Venue

IBM

Related People

Beglin, TW: AUTHOR [+6]

Abstract

PHYSICAL MEDIA ORGANIZATION The Laser Magnetic Storage International (LMSI) 12" optical disk media is a double-sided media. Each side contains 32,000 tracks. Each track contains 32 sectors of a total of 1,024,000 sectors per side of the media. The sectors are numbered 0 through 1,023,999. The lowest numbered sector is located at the innermost radius of the optical disk media. The sector numbers monotonically increase by one towards the outermost radius of the optical disk media. Each sector contains 1024 bytes of user data. DEFECTIVE SECTOR MANAGEMENT

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Directory Structure and Data Layout for the Efficient Writing and Reading of Data on 12" Write Once Read Many Optical Disk MEDIA

       PHYSICAL MEDIA ORGANIZATION
The Laser Magnetic Storage International (LMSI) 12" optical disk
media is a double-sided media.  Each side contains 32,000 tracks.
Each track contains 32 sectors of a total of 1,024,000 sectors per
side of the media.  The sectors are numbered 0 through 1,023,999.
The lowest numbered sector is located at the innermost radius of the
optical disk media. The sector numbers monotonically increase by one
towards the outermost radius of the optical disk media.  Each sector
contains 1024 bytes of user data.
DEFECTIVE SECTOR MANAGEMENT

      The LMSI LD1200E/LD1250E optical disk drive supports three
methods of defective sector management:
*  No Recovery
*  Auto Rewrite
*  Auto Reallocate
NO RECOVERY

      If the No Recovery method of defective sector management is
selected, when the drive encounters a defective sector during the
execution of a SCSI WRITE command, the write command is failed and
the sense data contains the sector number of the sector that could
not be written.  The host processor is responsible for issuing
another SCSI WRITE command, for the sectors not written, starting at
the sector following the sector in error.  This method of defective
sector management puts the responsibility of handling defective
sectors with the host processor.
AUTO REWRITE

      If the Auto Rewrite method of defective sector management is
selected, when the drive encounters a defective sector during the
execution of a SCSI WRITE command, the defective sector is skipped
and the data is written into the following sector.  If the following
sector is defective, the drive skips it and writes the data into the
next sector.  For each defective sector, the drive will attempt to
rewrite the data into the following sector.  The drive will attempt
to rewrite the defective sector up to 5 times, using 1 additional
sector each time a rewrite is attempted.  Therefore, a maximum of 6
sectors (1 original and 5 retries) can be used in the process of
writing a single sector.

      This method of defective sector management puts the
responsibility of handling defective sectors with the drive. With
this method of defective sector management there are 1,024,000
available sectors on each side of the optical media.  This method of
defective sector management has good performance characteristics
since the data is written into the next sequential sector, thus
avoiding any additional revolutions or seeks to other areas of the
media.  This method of defective sector management is best suited to
applications that fill up the media sequentially from lowest sector
numbers (contained on the innermost radius) to highest sector numbers
(contained on the outermost radius).
AUTO REALLOCATE

      If the Auto Reallocate method of defective sector management is
selected, when the drive encount...