Abstract: A method and apparatus for updating CKD data stored on fixed block media, and more particularly to creating Track Format Descriptors which are data structures loaded into electronic memory to enable fast writing of data without loading an entire CKD emulated track of data into memory. A control unit is provided with logic to provide Track Format Descriptors which describe the format of the track without the need for the data content of the track to be resident in cache, or electronic memory. An emulated CKD volume corresponds to a volume of data stored on a multi-disk device. Each track on a volume is represented by a Track Format Descriptor. The Track Format Descriptor forms a representation of the format according to the following general procedure. If the format is a predefined format, in other words one that is already known by the control unit then a track form descriptor is formed to represent the format. If the format is easily discernible, it is said to be "well behaved".

Abstract: A method and system are disclosed for permitting high concurrency of access during backup copying of designated data stored within a storage subsystem which includes multiple storage devices coupled to the data processing system via a storage subsystem control unit having subsystem memory therein. Data within each storage device is accessed utilizing a Unique Control Block (UCB), which identifies a selected storage device, and an associated data retrieval command sequence which identifies the data to be accessed. Portions of the data copied to subsystem memory within the subsystem storage control unit as sidefiles from a first storage device may be accessed utilizing a Unique Control Block (UCB) associated with an alternate storage device by associating a selected data retrieval command sequence therewith which identifies the data as stored within the subsystem memory.

Abstract: A method and system are disclosed for enhanced efficiency of backup copying of designated datasets stored within a plurality of storage devices coupled to the data processing system via a storage subsystem control unit having subsystem memory therein. Application execution within the data processing system is temporarily suspended long enough to form a dataset logical-to-physical system address concordance to be utilized to administer copying of the designated dataset. Thereafter, application initiated updates to uncopied portions of the designated datasets are temporarily deferred until sidefiles of the affected portions of the designated datasets are written to subsystem memory. The updates are then written to the storage subsystem. Portions of the designated datasets are then accessed and copied from the storage subsystem on a scheduled or opportunistic basis utilizing selected data retrieval command sequences.