CDR-RW Mount Ranier

Though ubiquitous not long into the new millennium, drag&drop writing of data to CD-RW media was still not supported at the operating system level, relying on special packet-writing applications based on the UDF file system. Discs that are written in this way are not automatically readable by other CD-RW drives or CD-ROM drives, but require a special UDF-reader driver. If the reliance on proprietary software and the issues of incompatibility weren’t enough, new CD-RW discs need to be formatted before they can be written to; a time-consuming process especially for older CD-RW drives.

The purpose of the proposals made by the Mount Rainier group – led by industry leaders Compaq, Microsoft, Philips Electronics and Sony – was to address these shortcomings and make the use of CD-RW media comparable to that of a hard or floppy disk. Finalised in the spring of 2001, the principal means by which the Mount Rainier specification sought to achieve these objectives was by enabling operating system support for the dragging and dropping of data to CD-RW media and by eliminating formatting delays.

The Mount Rainier specification has a number of key elements:

  • Physical defect management by the drive: Most conventional CD-RW packet writing solutions use the defect management handling that comes as part of UDF 1.5. The problem with this is that it requires software to have knowledge of drive and media defect characteristics and capabilities. Mount Rainier-compliant drives support defect management at the hardware level, so that when an application attempts to write data to a bad sector, that sector can be hidden and an alternative sector used instead.
  • Logical write-addressing at 2K: Conventional CD-RW uses a block size 64KB. Mount Rainier defines support for 2K logical addressing as a mandatory requirement, thereby bringing CD-RW drives into line with other data storage systems, which are generally based on 2K or 4K addressability.
  • Background formatting: Mount Rainier eliminates both the delay and the need to use third party software associated with conventional CD-RW media formatting by performing this as a background task that’s transparent to the user and that over within a minute. Also, media eject times have been brought into line with those of CD-ROM drives.

Less than a year after its successful implementation in CD-RW systems, the DVD+RW Alliance announced the availability of the final Mount Rainier specification for its rewritable DVD format.