Byte File Systems

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An OpenExtensions user can create, store, and access the Byte File Systems familiar to UNIX users (and similar to the file systems of DOS and OS/2 and to the hierarchical file system of OS/390).

Byte File System Characteristics

With the Byte File System support provided by OpenExtensions for z/VM services:

Filenames and pathnames can be much longer than with traditional CMS file identifiers.

Terminals and communication pipes are accessed as files.

The Byte structure encourages an enterprise and its users to organize sets of files in a natural way (for example, by area, by department, by group of users, by user, and so forth).

OpenExtensions for z/VM services provide facilities to make accessible (or remove from accessibility) different subsets of files in any Byte structure by logically mounting any particular hierarchy. A particular hierarchy that has been mounted can later be unmounted.

An OpenExtensions for z/VM Byte File System is a new type of CMS file system called a BFS (Byte File System). Byte files and traditional CMS files can be copied back and forth using the OPENVM PUT and OPENVM GET commands.

OpenExtensions for z/VM also introduces the concept of external links to the Byte File System. An external link can be thought of as a symbolic link to non-Byte File System files. It associates a CMS record file with a BFS path name. That is, an external is a file that contains the name of an object kept outside the Byte File System. Using an external link, you can associate that object with a POSIX-conforming BFS path name. If the link is to a CMS record file, you can use the path name to access the file. For example, you can create an external link to map /u/donovan/helloworld to HELLOW MODULE A.