Mount Rainier (packet writing)

Mount Rainier refers to a format for storage on optical media using packet writing and defect management with the aim to replace disks in the long term. The name comes from the eponymous volcano Mount Rainier in the United States of America.

Mount Rainier - short MRW for Mount Rainier Read / Write - comes only designed for this purpose drives are used. As a volume, but standard media, such as CD- RW and DVD ± RW can be used.


An integrated in the drive logic ensures that an inserted medium for the operating system looks like a physically empty area that can be formatted and written like a floppy or hard disk. There is therefore no requirement to use for the file system.

Internally, the drive uses the UDF file system. When formatting a few blocks for the defect management also be rented. Bad sectors are in a table in the lead-in, and a copy of this table in the Lead -out shall be recorded. Formatting a new blank happens in the background and so requires only about one minute.

From the perspective of an operating system, a re-written medium in an MRW drive is simply unused, fault-free, blockadressierbarer space that it can use in the usual way. Such MRW medium can therefore also with FAT32, NTFS or ext3, etc. are formatted, even though UDF is the recommended file format, because it is best designed for working with optical media and also the most common and across operating systems will spread. A MRW - formatted CD -RW with UDF file system will hold approximately 500 MB of data.

Mount Rainier allows the use of a medium after a few seconds after it has been inserted: data can already be written during the " spin up " to the media, even during the formatting phase. Before Mount Rainier you had a rewritable optical media first manually formatting, which took several minutes and had to be carried from one intended application. Only after formatting you could access with other applications on the newly formatted empty medium. MRW -formatted media can be read with special programs to non - MRW -compatible drives are not described. Such a program, for example, EasyWrite Reader for Microsoft Windows.

As an alternative to MRW drives makes sense to optical media manually using UDF in version 1.5 or later format. Therefore, a packet writing program to be used or the operating system supports on its own UDF in version 1.5 or higher. The capabilities of Mount Rainier and UDF 1.5 are partly similar.

Benefits of MRW over UDF 1.5 :

  • MRW allows quick formatting of optical media in the background
  • MRW uses a smaller package size over conventional packet-writing programs (2K over 64K)
  • MRW it possible to use any type of file system on an optical medium
  • The defect management operates independently of the operating system used

Benefits of UDF 1.5 compared to MRW:

  • UDF does not require any special hardware, so no MRW drive
  • UDF is wider support

Operating System Support

Mount Rainier is fully implemented in Windows Vista. Linux support is for Linux kernel 2.6.2. AmigaOS 4 supports Mount Rainier since the first beta version of 2004.

Operating systems without Mount Rainier support ( especially Windows XP and earlier versions ) require drivers from third-party manufacturers to use the MRW function of the drives can. Most packet-writing programs for Windows support in addition to the conventional UDF function also MRW.

The marketing logo for Mount Rainier compatible drives is designed by Philips EasyWrite logo. It aims to ensure that all marked with this logo products are tested and meet the established quality standards.