Abstract: Channel-to-channel communications is provided by integrating channel-to-channel functionality into one or more communication channels of a computing environment which may include heterogenous computer systems. The one or more channels having the integrated CTC function are non-dedicated channels also capable of conventional channel functionality. Work units at such channels are forwarded to either the CTC function or the channel function based on work unit type. Further, a facility is provided for. automatically deciding which of the first channel and the second channel is to provide the CTC function for a CTC connection. Partition-to-partition communication can also be accomplished using the integrated CTC function by establishing an internal logical path between a first logical partition and the CTC function and a second logical path between a second logical partition and the CTC function.

Abstract: Validation of a re-initialized CTC connection between a first channel and a second channel is provided in a computing environment in which a CTC CU function can be provided in either channel after initialization of the CTC connection and can move from one channel to the other after re-initialization of the connection. After initialization, a newly formatted CDR having a device NED and a specific NEQ is stored. After re-initialization, a current CDR with the same format is obtained. The re-initialized CTC connection is validated if the stored set of NED and NEQ values match the current values, in any order.

Abstract: A method, program product and apparatus for checkpointing for recovery of channels in a data processing system using a protocol which allows for multiplexing operations at the frame level and streaming of commands and data. For unsuccessful retries, the correct primary CCW address is reported back to software indicating the extent to which the channel completed modifying and accessing S/390 storage.

Abstract: Channel-to-channel communications is provided by integrating channel-to-channel functionality into one or more communication channels of a computing environment which may include heterogenous computer systems. The one or more channels having the integrated CTC function are non-dedicated channels also capable of conventional channel functionality. Work units at such channels are forwarded to either the CTC function or the channel function based on work unit type. Further, a facility is provided for automatically deciding which of the first channel and the second channel is to provide the CTC function for a CTC connection. Partition-to-partition communication can also be accomplished using the integrated CTC function by establishing an internal logical path between a first logical partition and the CTC function and a second logical path between a second logical partition and the CTC function.