Managing Hierarchical File System Data Sets

A hierarchical file system (HFS) data set is a data set that contains a POSIX-compliant hierarchical file system, which is a collection of files and directories organized in a hierarchical structure that can be accessed using z/OS® UNIX system services. You can use many of the standard BSAM, QSAM, BPAM, and VSAM interfaces to access data in z/OS UNIX HFS files. Most applications that use these access methods can access HFS files without reassembly or recompliation.

The contents of HFS data sets are structured like a tree, based on a root directory with various subdirectories. The files within an HFS data set are identified by their path and file names.

DFSMShsm can automatically back up HFS data sets if it is using DFSMSdss as its data mover, but it cannot back up individual files within an HFS data set.

Once you evaluate z/OS UNIX and decide to install it in your enterprise, you may proceed with the following planning tasks:

Deciding which DASD devices will contain the HFS data sets
Deciding how to control access to them
Structuring the file systems
Determining backup, restore, and expiration date policies
Determining HFS naming policies (file names can be up to 255 characters long and path names can be up to 1023 characters)
Defining data classes, management classes, and coding ACS routines and JCL statements for HFS data sets