What is the Integrated File System (IFS)?

The Integrated File System (IFS) is a file system used in IBM i, the operating system for IBM Power Systems servers.

The IFS is a hierarchical file system that provides a unified view of various file storage areas, including:

Traditional IBM i libraries and objects (e.g., programs, data files, etc.)
UNIX-like file system directories and files
Network file systems (e.g., NFS, SMB/CIFS)
Other storage areas

The Integrated File System (IFS) enables IBM i applications to access and manage files through a standard file system interface, akin to those found in UNIX or Windows. This offers a contemporary and adaptable approach to file management, which is a significant advancement over the conventional library-based file system of IBM i.

Key features of the IFS include:

Hierarchical directory structure

Support for long file names (up to 255 characters)

Access control lists (ACLs) for file and directory permissions

Integration with IBM i security and user profiles

Support for various file types (text, binary, stream files, etc.)

Ability to mount network file systems (e.g., NFS, SMB/CIFS)

The Integrated File System (IFS) is a crucial element of the IBM i operating system, facilitating contemporary file management features and seamless integration with various systems and platforms.

What is a stream file?

Apart from the original "library" file system, the majority of file systems within the IFS hold their objects in a recognizable file structure, typical to the Windows and UNIX environments.

There are many file systems defined to work in the IFS.

IFS objects are referred to as "stream files" because they consist of data viewed as a continuous stream of bytes. Essentially, there is a beginning and an end to the file, but no other structure is specified. A program can utilize this extensive string of bytes for any desired purpose.

Here are just a few examples to give you an idea:

/QSYS.LIB The traditional "Library file system"

/QDLS The "Document Library Services" (OfficeVision) file system MS-DOS

/QOpenSys The "Open Systems" file system UNIX / ("root") The "root" file system like Windows