International Business Machines Corporation

Vincent K Allen

Richard Anthony Ripberger

Scott Milton Fry

Jerry Wayne Pence

Wayne Erwin Rhoten

Warren B Harding

Robert G Long

Steven Douglas Johnson

Robert Samuel Goncharsky

A computer media tape cartridge has a multiple volume selector switch with a plurality of positions which allow a user to physically segment the tape into a corresponding number of sections for more efficient use of the tape. By moving the switch to a desired position, the user may select and use the tracks in one or all of the positions on the tape. These positions include an 'all position' wherein the tape is a single volume for reading and writing data, and individual positions wherein only the selected position is available for reading or writing data to the tape. Using the cartridge in the latter manner physically segments tape into four separate volumes. The cartridge is used in a tape drive having a plurality of sensors for detecting the position of the switch.

Multiple volume computer media tape cartridge

A peripheral data storage subsystem has means for responding to a MOUNT command received from a host processor to create and mount a host-processor-addressable logical data-storage volume. Such logical data-storage volume has a serial number VOLSER indicated in the MOUNT command. The logical data volume is assigned a predetermined area of a physical data volume, such area being termed a partition. The illustrated embodiment shows a tape subsystem in which the partitions are accessed by a control using a reel tachometer that identifies segments of the tape. Each partition has a number of the tape segments. Controls and methods are described for initializing the subsystem for effecting the automatic volume creation, appending data into a logical volume, how logical volumes are made to be portable, moving logical volumes amongst diverse physical media, tape formats usable for such logical volumes, data base control of the logical volumes and volume creation processing. The physical volume in which one or more logical volumes reside is not host-processor addressable. Some physical volumes are ejectable from the data storage subsystem. The physical volumes storing the logical volumes are not ejectable. To eject a logical volume, it is copied from the storing physical volume to an ejectable physical volume.

System for storing and managing plural logical volumes in each of

An adaptive data transfer channel providing means for a data management access method (AM) to define the channel subsystem data block transfer size and to transfer an extended data block (EDB) by a single channel transfer command to avoid repeated channel command word (CCW) command decode and status presentation operations. The adaptive scheme of this invention is transparent to the user and downwardly compatible with existing data record storage formats because it is independent of the user application program. The host software in the central processing complex (CPC) tests the peripheral data storage device (PDSD) to ensure compatibility with the EDB CCWs before selecting the channel program (CP) to be used for data block transfer in the subchannel. In the EDB format, the PDSD microcode permits the accumulation of logical data blocks (LDBs) from storage to form a single large EDB before transfer to the CPC responsive to a single transfer command. Conversely, the CPC can transfer a single EDB to the PDSD where it is parsed to form data records in an existing data record storage format, thus ensuring complete downward compatibility with existing data record storage formats.

Extension of data block capability in a data transfer channel

Adaptive data transfer channel employing extended data block capability

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Tucson, AZ, United States of America

Vincent K Allen