Abstract: Disclosed is a method, system, program, and memory for erasing data. A table is provided indicating different groupings of system functions. Each grouping indicates at least one system function. For each grouping there is code to perform erase operations. An erase command to erase data in at least one storage location is received. A determination is then made of the grouping having system functions supported by the system and the table is processed to determine the code for the determined grouping. The code for the determined grouping is executed to perform erase operations with respect to each storage location.

Abstract: Disclosed is a system for indicating system capabilities. A first processing unit, such as a control unit, receives a command from a second processing unit, such as a host system, indicating capabilities of the first processing unit. The first processing unit determines common capabilities indicated in the command that are also available in the first processing unit and indicates in a data structure, such as a bitmap data structure, the common capabilities. The first processing unit then signals the second processing unit of the change in system status.

Abstract: Disclosed is a system for dynamically assigning alias addresses to base addresses referencing an I/O device, such as a direct access storage device (DASD). In the system, at least one base control block indicates a base address and a plurality of alias control blocks indicate a plurality of alias addresses. Each control block is associated with an address for addressing an I/O device. A processing unit, such as a host computer system, processes at least one alias control block associated with the I/O device and determines a base control block associated with the I/O device with which the alias control blocks are associated. The processing unit then binds at least one alias control block to the determined base control block. The bound base and alias control blocks provide different addresses to address the same I/O device.

Abstract: Disclosed is a system for performing input/output (I/O) operations with a processing unit. A processing unit, such as a host system, determines a base and associated alias addresses to address an I/O device, such as a direct access storage device (DASD). The processing unit associates the determined base and alias addresses to the I/O device. The association of base and alias addresses is maintained constant for subsequent I/O operations until the processing unit detects a reassignment of the association of base and alias addresses. The processing unit then determines an available base or alias address to use with an I/O operation and may concurrently execute multiple I/O operations against the I/O device using the base and alias addresses.

Abstract: Disclosed is a system for reassigning addresses. A first processing unit, such as a storage controller, provides at least two base addresses for addressing devices, such as volumes of a direct access storage device (DASD) and a plurality of alias addresses. An alias address associated with a base address provides an address for addressing the device addressed by the base address. The first processing unit processes a command transmitted from a second processing unit, such as a host system that accesses the DASD through the storage controller, to reassign an alias address from a first base address to a second base address. The first base address addresses a first device and the second base address addresses a second device. The first processing unit then indicates that the alias address to reassign is not associated with the first base address and is associated with the second base address. The second device addressed by the second base addresses is capable of being addressed by the reassigned alias address.

Abstract: In summary, preferred embodiments disclose a system, method, and program for data transfer commands to perform data transfer operations between a first processing unit and second processing unit. The second processing unit controls access to a storage system. The storage system storage space is logically divided into multiple tracks. Each track includes one or more data records. Each data record includes an index area providing index information on the content of the data record and a user data area including user data. An initialization command is communicated from the first processing unit to the second processing unit indicating a range of tracks on which data transfer operations will be performed. For each track in the range of tracks, a set of data transfer operations is executed. This set of data transfer operations includes transmitting a data transfer command from the first processing unit to the second processing unit.

Abstract: A disaster recovery system providing remote data shadowing between a primary and a secondary site uses a method and apparatus for swapping, or switching, host directed I/O operations from a primary data storage device to a secondary data storage device in a remote copy duplex pair. Application programs running in a host processor at the primary site first quiesce all I/O operations and record updates targeted to the primary data storage device. The remote copy duplex pair is checked to verify that the secondary data storage device is a fully synchronized copy of the primary data storage device.