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Computing  The CD Recording Service

The Department has a CD Recorder and the Computing staff can help members of the Department with the process of archiving files, from any machine attached to the network, to a recordable CD-ROM. Blank recordable discs are available from Stores and hold around 600Mbytes of data.

Transferring Your Files

If the files are already on the file server, or another Unix machine, then simply take your blank disc to the Computer Officer, and tell him where the files are stored.

If the files are currently on a PC or Mac then you will need to copy them to your home directory on the file server (it is easiest if you create a new folder and then lay out the files under this folder as you want them to appear on the CD), then bring a blank to the Computer Officer.

CD-ROM Filenames

The discs that we produce use the standard ISO 9660 filesystem. This format has the advantage that it can be read by virtually every type of computer available, but it imposes various limitations which you should be aware of when preparing your files.

The rules for naming files on CD-ROMs are similar the old DOS filename rules: they can be a maximum of eight characters long, with an optional three character extension after the dot, the character set is limited to uppercase letters, numerals and the underscore character ("_"). In addition, directory structures can only be nested up to eight levels deep. If any of your filenames fail to meet these restrictions then the files recorded on the CD-ROM will be automatically renamed such that they do.

In addition to the basic ISO-9660 format, the CD-ROMs that we write all include two special extended sets of filename information: one, called "Rock Ridge", records the original filenames as additional information which can be used by Unix-based computers; the other, called "Joliet", records similar hidden details which can be read by Windows 95, Windows 98 and Windows NT computers. If you use the disc on a computer that understands the extensions then the Rock Ridge or Joliet names are used in preference to the ISO 9660 limited names.

Although these extensions may seem to offer a solution to filename problems, always remember that they are not supported by all types of computer. If anybody tries to use the resulting CD-ROM with (for example) a Mac, a DOS machine or a Windows 3.1 machine then neither of the extensions work and the person using the disc will see the restricted filenames.

If you need compatibility across a variety of different types of computer, or the assurance that the disc will be fully usable in whatever sort of machine you might want to try in the future, then the best strategy is to plan (from the start) the filenames and directory layout of your data such that it complies with the ISO 9660 restrictions.