Why should I care?
The Mount Rainier format (DVD-MRW and CD-MRW) owes a lot to DVD+RW, another pet Philips technology, and offers some distinct advantages over conventional packet writing.
Less wasted time
Currently, packet-writing software takes anywhere from 2 to 20 minutes to fully format a CD-RW disc before you can write data to it or remove the disc from the drive. With Mount Rainier, the drive formats the media on its own, without the need for software, and lets you write data to the disc shortly after formatting (also called de-icing) begins, typically within a minute. Even if you eject the disc before the drive completes the formatting process, it can still be read by most other drives.
Less wasted space
According to the Mount Rainier standard, drives must also be able to write and retrieve data in 2KB increments rather than the 64KB or 32KB blocks required by current CD and DVD standards. This means you can write and retrieve small amounts of data faster and fit more data on a disc. The smaller data blocks also make MRW more compatible with current file and operating systems, and hence, easier to implement. (Linux has included support for Mount Rainier since kernel 2.4.19, in fact.) And with native OS support, you won't need third-party packet-writing applications such as Ahead Software's InCD or Roxio's Direct-to-Disc.
Every optical storage disc has defective sectors, or bad spots, where you can't store data safely. However, rewritable media has gotten a particularly bad rap because of the poor media-defect management offered by some older packet-writing applications. Mount Rainier promises better defect management. For starters, it makes the drive, rather than the software, check for errors. In addition, the MRW format sets aside spare sectors in case you encounter a bad sector when writing to the disc. The bad sector will be hidden and the spare used instead.
With the multitude of packet-writing applications on the market, there's currently no guarantee that the disc you just burned on your PC will play back in another machine without special software. Mount Rainier intends to cure this compatibility problem with its standardized file system. Currently, Linux kernel 2.4.19, Ahead Software's InCD, Roxio's Direct-to-Disc, and Software Architects' WriteCD-RW all support CD-MRW.