Abstract: A computer implemented method includes the steps of establishing a plurality of storage control sessions, wherein each storage control session associates at least one primary storage controller and at least one secondary storage controller with a predetermined path through a data transport network that interconnects the primary and secondary storage controllers; identifying storage control sessions that have data available to be transferred from primary storage controllers to secondary storage controllers; accumulating available data for each session and determining transfer time through the network for each data element to estimate prospective bandwidth utilization; and determining, for a predetermined time interval, whether transferring the available data would fully occupy available bandwidth of the data transport network for the predetermined time interval.

Abstract: When the mirrored point in time copy fails, at that point in time all the data for making the source and target of the point in time copy consistent is available on secondary volumes at disaster recovery site. The data for the source and target of the failed point in time copy are logically and physically equal at that point in time. This logical relationship can be maintained, and protected against ongoing physical updates to the affected tracks on the source secondary volume, by first reading the affected tracks from the source secondary volume, copying the data to the target secondary volume, and then writing the updated track to the source secondary volume.

Abstract: A computer-implemented method, carried out by one or more processors, for a modified asynchronous replication session. In an embodiment, the method comprises the steps of acquiring a lock on a volume configuration, where the lock prevents changes to the volume configuration between a first volume and a second volume at a remote site. Internal control block information is updated, where the update includes at least a volume serial number of the first volume matching a volume serial number of the second volume. Responsive to updating internal control block information, the acquired lock is released to allow changes to the volume configuration.

Abstract: A computer-implemented method, carried out by one or more processors, for a modified asynchronous replication session. In an embodiment, the method comprises the steps of acquiring a lock on a volume configuration, where the lock prevents changes to the volume configuration between a first volume and a second volume at a remote site. Internal control block information is updated, where the update includes at least a volume serial number of the first volume matching a volume serial number of the second volume. Responsive to updating internal control block information, the acquired lock is released to allow changes to the volume configuration.

Abstract: When the mirrored point in time copy fails, at that point in time all the data for making the source and target of the point in time copy consistent is available on secondary volumes at disaster recovery site. The data for the source and target of the failed point in time copy are logically and physically equal at that point in time. This logical relationship can be maintained, and protected against ongoing physical updates to the affected tracks on the source secondary volume, by first reading the affected tracks from the source secondary volume, copying the data to the target secondary volume, and then writing the updated track to the source secondary volume.

Abstract: A computer implemented method includes the steps of establishing a plurality of storage control sessions, wherein each storage control session associates at least one primary storage controller and at least one secondary storage controller with a predetermined path through a data transport network that interconnects the primary and secondary storage controllers; identifying storage control sessions that have data available to be transferred from primary storage controllers to secondary storage controllers; accumulating available data for each session and determining transfer time through the network for each data element to estimate prospective bandwidth utilization; and determining, for a predetermined time interval, whether transferring the available data would fully occupy available bandwidth of the data transport network for the predetermined time interval.

Abstract: A storage system improves error debugging by directing distributed system components associated with an error condition to temporarily suspend data processing for collecting failure information. The collected failure information is correlated for later analysis according to an issued diagnostic state save channel command word (CCW) that is triggered by the detection of said error condition. The storage system includes a host processor running applications generating record updates. A data mover in the host processor issues the diagnostic state save CCW upon receiving an error code from one of the system components. The failure information includes software, hardware and microcode control structures of the distributed system components.

Abstract: A remote data shadowing system provides storage based, real time disaster recovery capability. Record updates at a primary site cause write I/O operations in a storage subsystem therein. The write I/O operations are time stamped and the time, sequence, and physical locations of the record updates are collected in a primary data mover. The primary data mover groups sets of the record updates and associated control information based upon a predetermined time interval, the primary data mover appending a prefix header to the record updates thereby forming self describing record sets. The self describing record sets are transmitted to a remote secondary site wherein consistency groups are formed such that the record updates are ordered so that the record updates can be shadowed in an order consistent with the order the record updates cause write I/O operations at the primary site.

Abstract: A plurality of host processors share access to a peripheral data storage subsystem and each have program means for controlling asynchronous operations of the subsystem. Control blocks in each of the host processors are addressably linked together for enabling inferred access to a unit control block (UCB) for any of a plurality of peripheral devices in the subsystem. The subsystem selectively groups some of the devices such that only devices designated as primary devices are addressably accessible by host processor application programs. Other devices in the respective groups are secondary devices and are accessed by the subsystem whenever the primary devices in the same group cannot perform a host processor commanded operation. Means are provided for identifying the secondary devices to all of the host processors.