How VM and IOCP Worked

The IOCP updated the input/output configuration data set (IOCDS) that resided in the hardware support processor. This information was loaded into the hardware system area during power-on reset (POR). Without dynamic reconfiguration of CP, if the configuration was changed, it was necessary to write a new IOCDS using IOCP and to load it into the hardware system area with a POR.

CP created the control information (such as RDEV control blocks) needed by z/VM to describe the hardware configuration.

Dynamic reconfiguration management is the ability to select a new I/O configuration during normal processing and without the need to perform a power on reset (POR) of the hardware or an initial program load (IPL) of the operating system.