What is IODF?

IODF stands for Input/Output Definition File. In the context of IBM mainframe systems (z/OS), the IODF is a dataset that describes the hardware configuration of the system's I/O subsystem. It contains information about channels, control units, and devices connected to the system. The IODF is used by the Hardware Configuration Definition (HCD) component to define and manage the I/O configuration. This definition is then used to generate an I/O configuration program (IOCP) deck, which is loaded into the Support Element (SE) or Hardware Management Console (HMC) to activate the I/O configuration. It essentially tells the mainframe operating system and hardware how to communicate with peripheral devices like disk drives, tape drives, and network adapters.