Characteristics of an IOCDS

The definitions for channel paths, control units, I/O devices, and PCIe functions are processed by the IOCP and stored in an IOCDS. During initialization of the CPC, the definitions of a selected IOCDS are transferred to the hardware system area (HSA). The IOCDS is used to define the I/O configuration data required by the CPC to control I/O requests.

Channel paths in an IOCDS are assigned to one or more LPs. The characteristics of an IOCDS are:

• Using the IOCP RESOURCE statement, you define logical channel subsystems (CSSs) and the logical partitions that have access to the channel paths in a CSS.
• Using the IOCP RESOURCE statement, you can name logical partitions and assign MIF image ID numbers to them. MIF image ID numbers are necessary for FICON® CTC definitions.
• Using the IOCP CHPID statement, you can assign a channel path as reconfigurable or shared.
• Using the IOCP CHPID statement, you can specify a Dynamic CHPID Management (DCM) channel path and the cluster to which the CHPID belongs. The CHPID is shareable among active LPs that have become members of the specified cluster.
• You can duplicate device numbers within a single IOCP input file, but the device numbers cannot be duplicated within an LP. See IOCP coding specifications .