Abstract: A failure threshold host command that provides a host with the capability to tune a storage controller path failure threshold based on the host application performance requirements. The failure threshold host command comprises path failure threshold rules that the storage controller uses to determine when a CHPid has reached a failed state condition.

Abstract: A failure threshold host command that provides a host with the capability to tune a storage controller path failure threshold based on the host application performance requirements. The failure threshold host command comprises path failure threshold rules that the storage controller uses to determine when a CHPid has reached a failed state condition.

Abstract: A system for providing hosts with a capability to determine which threshold rule of a plurality of threshold rules to use based upon threshold consensus. For example, the system would address a configuration case of several hosts sharing an output port of a fabric via zoning and that port being connected to a single port of a storage controller. If one host is executing lower priority jobs and its threshold is much higher than another host with higher priority jobs and a lower threshold, and the storage controller recognizes that several hosts are sharing the same storage controller port, the consensus will be to ignore the threshold of the first host and to use the threshold of the second host to prevent performance degradation in the system.

Abstract: A system and method for recovering from a single logical path failure. More specifically, although a host has not grouped its logical paths, the host knows which logical paths it has available. When a host detects a logical path failure, the host enters a path discovery mode of operation. If the host continues to detect a logical path failure while operating in the logical path discovery mode of operation, the host removes the logical path from a logical path mask, and the host does not use the removed logical path again. In the case of ungrouped logical paths, the host aborts its process because it does not have more paths available to continue its process. Additionally, in certain embodiments, a pseudo path group for ungrouped logical paths is created.

Abstract: A computer program product, an apparatus, and a method for processing communications between a target and an initiator an input/output processing system are provided. The computer program product includes a tangible storage medium readable by a processing circuit and storing instructions for execution by the processing circuit for performing a method. The method includes: sending a message from the initiator to the target, the message requesting suspension of input/output operations between the initiator and the target for a period of time, the period of time being defined by the message; responsive to the message, suspending input/output operation messages for the period of time; performing a system change comprising at least one of: at least one update, a computer program installation, a recovery, and a change in operating parameters; and initiating new input/output operations after at least one of: expiration of the period of time and initiation of new input/output operations by the initiator.

Abstract: A method for transferring data over a network operating in accordance with a protocol, such as the ESCON protocol, that supports a limited logical address range includes establishing a logical path over the network from a host or other device to a second device, such as a storage system, using path logical addresses within the given logical address range. A virtual path is created over the logical path to carry the data from the source to the target, wherein the target logical subsystem has a subsystem logical address which is outside the given logical address range.

Abstract: A system, apparatus, and method dynamically manages logical path resources by adding, removing, and establishing logic paths based on specified priority schemes associated with the logical path resources. Information associated with the logical path resources is updated in a logical path resource table.

Abstract: A method for replacing logical path resources, a host is able to replace a logical path it owns with a new logical path. Such a system is especially applicable when the condition of “out of resources” has been reached for a port. With this system, a host is guaranteed that it can replace a logical path it owns with a new logical path. It is not necessary for a control unit to have reached its maximum number of logical paths per port. A host is able to replace one logical path with a new logical path any time.

Abstract: A remote copy system incorporates dynamically modifiable ports on the storage controllers such that those ports can operate either as a control unit link-level facility or as a channel link-level facility. When configured as a channel link-level facility, a primary storage controller can appear as a host processor to a secondary storage controller. Using dynamic switches coupled between primary and secondary sites, fewer ESCON communication links are required since the ESCON communication links can function either as a channel or as storage controller communication link.