zFS
The z/OS File System: the type of file system that holds Unix files and directories on z/OS.
Also written z/OS File System, HFS, Unix file system, mount
zFS, the z/OS File System, is how z/OS stores Unix files and directories, the ones you see under paths like /u/yourname or /etc in Unix System Services.
Each zFS file system is kept inside a VSAM dataset. To use it, it is mounted at a directory, the same idea as mounting a disk on Linux. Once mounted, its files look like normal Unix files: named with paths, organised in directories, and stored as streams of bytes rather than records.
That last point matters. Traditional datasets hold records with a fixed format. Unix files do not. Moving data between the two needs a step that turns records into lines and back, using commands such as OGET and OPUT, or the cp command with a dataset name.
You may also see HFS, the older file system type that zFS replaced. Many modern tools on z/OS, such as Java programs, web servers and parts of Zowe, keep their files in zFS. A system programmer creates and mounts the file systems; most users only see the directories.
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- Unix System ServicesA full Unix environment built into z/OS, with a shell, directories and files alongside the traditional mainframe world.
- VSAMA family of dataset types built for fast record access by key, used where applications need to look records up rather than read them in order.
- DatasetWhat a mainframe calls a file: a named collection of records with a defined structure, rather than a loose stream of bytes.
- File transferMoving data between the mainframe and other systems, where character encoding and record structure both need attention.
- z/OSThe main operating system that runs on IBM mainframes, in the same way Windows or Linux runs on a laptop or server.