A z/OS UNIX file system is a section of the UNIX file tree that is physically contained on a single device or disk partition, and that can be separately mounted, dismounted, and administered. UNIX allows you to use a variety of file systems, including hierarchical file system (HFS), Network File System (NFS), z/OS File System (zFS), and temporary file system (TFS). UNIX files are byte-oriented. The view of the data to the end user is a hierarchical directory structure similar to IBM PC DOS. To access UNIX files, you specify the path leading to them, as shown in Figure 1.

Hierarchical file system

A hierarchical file system (HFS) is part of the operating system that includes the application programming interfaces. HFS enables an application that is written in a high-level language to create, store, retrieve, and manipulate data on a storage device.

Network File System

A Network File System (NFS) is a distributed file system that enables users to access files and directories located on remote computers and treat those files and directories as if they were local. NFS is independent of machine types, operating systems, and network architectures through the use of remote procedure calls.

With z/OS UNIX, you can use the NFS client to mount a file system, directory, or file from any system with an NFS server within your directory.

z/OS File System

A z/OS File System (zFS) contains one or more file systems in a VSAM linear data set. A zFS can be SMS-managed. You can share zFS files in a sysplex.

Temporary file system

A temporary file system (TFS) is stored in memory and delivers high-speed I/O. You can mount a TFS for storing temporary files.

Figure 1. UNIX Directories and Files in a File System

For more information, see z/OS UNIX System Services Planning and z/OS UNIX System Services User's Guide.