Abstract: A storage hierarchy has a caching buffer and a backing store; the backing store preferably having disk-type data-storage apparatus. A directory indicates data stored in the caching buffer. Upon a data-storage access, read or write, within a series of such accesses, resulting in a cache miss, all subsequent data storage accesses in the series are made to the backing store to the exclusion of the caching buffer even though the caching buffer has storage space allocated for such a data transfer. Selected limits are placed on the series to the backing store, such as receiving on end of series (end of command chain) indication from a using unit, crossing DASD cylinder boundaries, receiving an out of bounds address or receiving certain device oriented commands.

Abstract: A data-storage buffer transfers data signals with other units in relatively large blocks of data. Such large blocks storable in large address spaces are not always filled with meaningful data. To more efficiently use the data-storage space in the data-storage buffer, the allocatable unit or segment of the data buffer is made smaller than the data capacity of the large block. Each time a large block of data is to be written into the data buffer, a sufficient number of the segments for storing data of one large block is allocated for receiving the data. After the data of the one block is written into the data buffer, the allocated segments are examined; all of the allocated segments not storing data from the one large block are deallocated. The invention is particularly useful for data buffers acting as cached data storage for large-capacity direct-access storage devices (DASD) and are coupled to host processors programmed to operate with such DASD.

Abstract: A peripheral subsystem accepts and responds to a plurality of supervisory channel commands which alter the operation of the subsystem; i.e., logically partition, break the logical partition, adjust or amend the logical partition, ignore the logical partition, give operator controls for loading and unloading a record cartridge, suspending multipath reconnection and the like. These supervisory commands can be located anywhere in a I/O chaining sequence. Some of the supervisory commands will result in changes in the subsystem operation for the duration of the instant channel program or CCW chain while others persist for as long as the subsystem is operating or until a subsequent supervisory command overrides the previous supervisory command. One of the supervisory commands can selectively inhibit subsequent supervisory commands only within a given I/O chain. This selective inhibit provides subsystem integrity. At the end of the chain, the inhibition is removed.

Abstract: Data transfers between respective buffer segments and data source-sinks, such as peripheral data storage devices, are scheduled as a series of transfers based upon most recent, next most recent, to the least recent usage of the buffer segments by a utilization device. A list of segments ordered by such usage is dynamically maintained. Replacement of segment allocations among devices proceeds from the least recently used, next least recently used, etc. to the most recently used segments. Therefore a single list controls replacement and read ahead (prefetch) of data from devices to the buffer and transfer of data from the buffer to the devices, all based on utilization of the buffer by the utilization device.

Abstract: A storage hierarchy has a backing store and a caching buffer store. During a series of accesses to the hierarchy by a user, writing data to the hierarchy results in data being selectively removed from the buffer store. Space in said buffer store not being allocated to data being written results in such data being written to the backing store to the exclusion of the buffer store. Removal of data increases the probability of writing data to the backing store. In a preferred implementation, the backing store is one or more disk type data storage apparatus and the buffer store is an electronic random access memory.

Abstract: A cache is accessed based upon addresses to a backing store having a larger address space than the cache. The backing store consists of plurality of devices exhibiting delay access boundaries. The cache accessing is based upon a hashing method and system derived from the arrangement of the backing store and in an ordered manner for accommodating the delay access boundaries and enable rapidly adjusting the hash parameters in accordance with changes and backing store capability in other hardware changes.

Abstract: Data transfers between a host processor and a peripheral data recorder in a peripheral data storage system, such as tape recorder peripheral data storage system, are via a random-access buffer store in the peripheral data storage system and interposed between the peripheral data recorder and the host processor. A command queue storage in the peripheral data storage system stores commands received from the host processor for the peripheral data recorder. Additionally, apparatus in the peripheral data storage system form commands for transferring data between the peripheral data recorder and the buffer store without intervention of the host processor; both read transfers (data transfer from the peripheral data recorder to the host processor) and write transfers (data transfer from the host processor to the peripheral data recorder) are enabled via the formed commands.

Abstract: A single reel magnetic tape cartridge includes a leader block for interfacing with an automatic threading system in a tape drive. The leader block has a slot in its leading surface that precedes an enlarged receiving cavity. The cavity and slot interface with a coupling device in a positive connection to unwind the tape from the reel into the tape drive.

Abstract: The sputter deposition of a thin film of material on both sides of a thin substrate is performed by positioning the substrate sides orthogonal to the target and preferably radial to the deposition center of the sputter system. The vapor deposition of alumina on a thin ferrite core for a magnetic head is accomplished by positioning the ferrite substrate in the vacuum chamber orthogonally to the target and radial to the particle deposition center. The alumina is deposited on both sides of the ferrite core simultaneously to substantially the same thickness. The deposition on both sides of the ferrite core protects the core against width erosion, and minimizes bending stress. In addition, signal output of the ferrite core when used in a magnetic head is increased.

Abstract: In a data storage system employing sequential data transfers for blocks of data bytes, an address offset is induced in the addressing mechanism such that each block transfer requires loading the address mechanism with an address of a block to be accessed. Address offset is preferably induced by inserting a blank register between adjacent blocks.

Abstract: A peripheral device subsystem enables its peripheral devices to operate asynchronously with respect to attaches hosts through the use of managed buffers, new multiple data transfer modes, control and error recovery operations. In a preferred first or buffer mode of operation, all data of each record being transferred can be resident in a buffer before transfer to either a host or device. For a host to device write transfer, receipt of such a record by the buffer results in the subsystem signaling to the host a completion of a transfer to an addressed device even though the device has received none or only part of the data. In a second or tape write mode, recording data in a peripheral device, such as a tape recorder, completion of recording is not signaled until after the buffer has transferred the data to the recorder.

Abstract: A plurality of addressable data storage devices are selectively directly accessed or accessed via a cache memory. Access via the cache memory uses one of a plurality of logical addresses; each of the data storage devices is represented by a plurality of the logical addresses. Each of the data storage devices can be reserved for direct access; such reservation does not apply to device accesses via the cache. Accesses to the devices are queued on a device basis.

Abstract: In a storage hierarchy, promotion of data from a backing store to a caching buffer store is restricted based upon status of the cache and activity of a last storage reference. Observed writing activity selectively inhibits data promotion. Data promotion occurs after completion of a series of storage access requests. A peripheral data storage system is described.

Abstract: In a buffered data storage subsystem, data is promoted to the buffer in anticipation of a connected host using the promoted data in the near future. In a tape recorder data storage apparatus the actual position of the tape reflects the last promoted data; such actual tape position is "inconsistent" with host operations. If the sequence of host operations continues, such inconsistency actually enhances total operations. When the subsystem detects a change or possible change in future host operations (rewind command, change in tape motion direction, etc.), detect end of file (tape mark) or a change in subsystem operations (load balance affecting drive or deallocation of buffer from drive) the data promoted to the buffer and not read by the host is erased from the buffer. The tape is moved such that upon a forward motion the tape drive would next read data on tape corresponding to the data block erased from the buffer.

Abstract: A single reel tape cartridge is disclosed for an automatic threading tape drive. The reel includes layers of magnetic tape with a leader block attached to the free end of the tape. The leader block is held in a receiving well in one corner of the cartridge when the cartridge is out of a tape drive. The leader block interconnects with a threading pin in the drive for threading the tape through the drive to a take-up reel hub. The leader block includes conforming sections that fit the leader block into a U-shaped channel in the hub to provide a smooth hub periphery for the layers of tape.

Abstract: A peripheral system has one or more buffered control units connected to a plurality of peripheral devices. Operation times of the devices are marked by the buffer and controls which overlap device operations, queue device operations in a priority set of queues, and prioritize peripheral system operations. Plural specialized interconnections between each control unit and the devices include a preparatory connection for transfer of preparatory commands to devices, a tag or control connection for device selection, deselection and control and a data-command connection for signal transfers between a selecting control unit and a selected peripheral device.

Abstract: Data associated with a defective area of a backing store and stored in an alternate area, such as defective and alternate tracks in a direct access storage device, is selectively stored in a high speed buffer front store based upon usage of such data. A first replacement control governs buffer operation for data from good areas of the backing store, and a second independent replacement control governs buffer operation for data from alternate storage areas. Limitations are imposed on the amount of data subject to the second replacement control.

Abstract: The sputter deposition of a thin film of material on both sides of a thin substrate is performed by positioning the substrate sides orthogonal to the target and preferably radial to the deposition center of the sputter system. The vapor deposition of alumina on a thin ferrite core for a magnetic head is accomplished by positioning the ferrite substrate in the vacuum chamber orthogonally to the target and radial to the particle deposition center. The alumina is deposited on both sides of the ferrite core simultaneously to substantially the same thickness. The deposition on both sides of the ferrite core protects the core against width erosion, and minimizes bending stress. In addition, signal output of the ferrite core when used in a magnetic head is increased.

Abstract: A two-level storage system selectively enables early discard of data from an upper level either immediately or at the end of a predetermined sequence of operation. A copy of data in such upper level is discarded immediately while altered copies of data are discarded at the end of the predetermined sequence of operations. Error conditions inhibit discarding altered data.

Abstract: In a storage subsystem employing removable record media such as contained in a cartridge, each storage recorder has a multidigit alphanumeric display located immediately above a cartridge receiver. The symbols on the display are arranged to be aligned with the symbols on the cartridge when inserted into recorder so that visual correlation is facilitated. Each recorder has a microprocessor which controls the display in response to host supplied LOAD DISPLAY commands. Each command includes a cartridge identification field for displaying on the display for such verification as well as orders for setting up display modes and display sequencing. The recorder microprocessor will display status of the recorder in response to a control field of the LOAD DISPLAY message at predetermined drive states, display a cartridge number after a cartridge has been removed from the recorder (i.e., the number of the cartridge to be inserted), inhibit a recorder status message or error message until the recorder is READY, i.e.