Abstract: In one embodiment, a product includes a magnetic medium having written thereon data in a data track. The data includes encrypted data written over unencrypted data. An indicator of a physical position on the magnetic medium that corresponds to an end of the encrypted data is stored on the product. A product according to another embodiment includes a magnetic medium having written thereon data in a data track. The data includes encrypted data written over unencrypted data. A portion of the unencrypted data is located before the encrypted data on the medium. An indicator of a physical position on the magnetic medium that corresponds to a beginning of the encrypted data is stored on the product.

Abstract: A method for dynamically changing a buffer threshold in a tape drive, according to another embodiment, includes monitoring a history of sizes of data transactions between sync commands, the data transactions being from a host to a tape drive, determining that a next sync command is expected to be received relatively sooner or relatively later based on the history of data size transactions, writing buffered data to a magnetic recording tape in response to determining that the next sync command will be received relatively sooner, and increasing a buffer threshold for delaying writing to the magnetic recording tape in response to determining that the next sync command will be received relatively later. A computer program product according to one embodiment includes a computer readable storage medium having program code embodied therewith, the program code readable/executable by a processor to perform the foregoing method.

Abstract: A method for dynamically changing a buffer threshold in a tape drive, according to another embodiment, includes monitoring a history of sizes of data transactions between sync commands, the data transactions being from a host to a tape drive, determining that a next sync command is expected to be received relatively sooner or relatively later based on the history of data size transactions, writing buffered data to a magnetic recording tape in response to determining that the next sync command will be received relatively sooner, and increasing a buffer threshold for delaying writing to the magnetic recording tape in response to determining that the next sync command will be received relatively later. A computer program product according to one embodiment includes a computer readable storage medium having program code embodied therewith, the program code readable/executable by a processor to perform the foregoing method.

Abstract: According to one embodiment, a method for dynamically changing a buffer threshold in a tape drive includes determining that a drive buffer is emptied of data, calculating a write size indicating an amount of data from a transaction size left to be written to a tape prior to a next anticipated sync command, setting a buffer threshold that triggers a back hitch to a smaller value when the transaction size is less than a buffer size, setting the buffer threshold to the smaller value when an absolute difference between the transaction size and the write size is greater than or equal to the buffer size, and setting the buffer threshold to a larger value when the transaction size is not less than the buffer size and/or the absolute difference between the transaction size and the write size is less than the buffer size.

Abstract: In one embodiment, a product includes a magnetic medium having written thereon data in a data track. The data includes encrypted data written over unencrypted data. An indicator of a physical position on the magnetic medium that corresponds to an end of the encrypted data is stored on the product. A product according to another embodiment includes a magnetic medium having written thereon data in a data track. The data includes encrypted data written over unencrypted data. A portion of the unencrypted data is located before the encrypted data on the medium. An indicator of a physical position on the magnetic medium that corresponds to a beginning of the encrypted data is stored on the product.

Abstract: In one embodiment, a system includes a processor and logic integrated with and/or executable by the processor, the logic being configured to: determine a physical position on a magnetic medium that corresponds to an end of an encrypted data set; store an indicator of the physical position on the magnetic medium and/or a memory coupled thereto; and cause obscuring of an unencrypted data set positioned after the physical position without overwriting the encrypted data set. In another embodiment, a computer program product includes a computer readable storage medium and program instructions embodied therewith, the program instructions readable and/or executable by the processor to cause the processor to: read an indicator of a physical position on a magnetic medium that corresponds to an end of an encrypted data set; and cause obscuring of an unencrypted data set positioned after the physical position without overwriting the encrypted data set.

Abstract: In one embodiment, a system includes a processor and logic integrated with and/or executable by the processor, the logic being configured to: determine a physical position on a magnetic medium that corresponds to an end of an encrypted data set; store an indicator of the physical position on the magnetic medium and/or a memory coupled thereto; and cause obscuring of an unencrypted data set positioned after the physical position without overwriting the encrypted data set. In another embodiment, a computer program product includes a computer readable storage medium and program instructions embodied therewith, the program instructions readable and/or executable by the processor to cause the processor to: read an indicator of a physical position on a magnetic medium that corresponds to an end of an encrypted data set; and cause obscuring of an unencrypted data set positioned after the physical position without overwriting the encrypted data set.

Abstract: A method, system and computer-usable medium are disclosed for reordering User Data Segment (UDS) lists to reduce seek times when accessing data stored on tape media. A host application sends a list of UDSs to a target tape drive and requests the tape drive to reorder the list to provide better performance. An ordered list of target User data Segments to retrieve from a target tape media is received. Information related to the location of each UDS on the target media is processed to determine its corresponding physical position on the tape media. The resulting physical positions are then processed to generate a reordered UDS list, where the order of the User Data Segments is reordered according to their physical location on the target tape media. The reordered list of User Data Segments is then used to perform seek, reposition and read operations to read User Data Segments from the tape media.

Abstract: In one embodiment, a system includes a processor, logic in the processor and/or memory configured to determine a physical position on a magnetic medium that corresponds to an end of encrypted data written over residual unencrypted data, and logic configured to store an indicator of the physical position on at least one of the magnetic medium and a memory coupled thereto. In another embodiment, a method includes determining a physical position on a magnetic medium that corresponds to an end of encrypted data written over residual unencrypted data, storing an indicator of the physical position on at least one of the magnetic medium and a memory coupled thereto.

Abstract: According to one embodiment, a method for dynamically changing a buffer threshold in a tape drive includes determining that a drive buffer is emptied of data, calculating a write size indicating an amount of data from a transaction size left to be written to a tape prior to a next anticipated sync command, setting a buffer threshold that triggers a back hitch to a smaller value when the transaction size is less than a buffer size, setting the buffer threshold to the smaller value when an absolute difference between the transaction size and the write size is greater than or equal to the buffer size, and setting the buffer threshold to a larger value when the transaction size is not less than the buffer size and/or the absolute difference between the transaction size and the write size is less than the buffer size.

Abstract: A system according to one embodiment includes a processor; logic in the processor and/or a memory configured to determine a furthest physical position on a magnetic medium that unobscured data has been written to; and logic configured to store an indicator of the furthest physical position on at least one of the magnetic medium and a memory coupled thereto. A system according to another embodiment includes a processor; logic in the processor and/or a memory configured to receive an instruction to obscure data on a magnetic medium; logic configured to read an indicator of a furthest physical position on the magnetic medium that unobscured data has been written to; and logic configured to cause obscuring of the unobscured data on the magnetic medium, and terminating the obscuring upon reaching the physical position in the indicator.

Abstract: A system according to one embodiment includes a processor; logic in the processor and/or a memory configured to determine a furthest physical position on a magnetic medium that unobscured data has been written to; and logic configured to store an indicator of the furthest physical position on at least one of the magnetic medium and a memory coupled thereto. A system according to another embodiment includes a processor; logic in the processor and/or a memory configured to receive an instruction to obscure data on a magnetic medium; logic configured to read an indicator of a furthest physical position on the magnetic medium that unobscured data has been written to; and logic configured to cause obscuring of the unobscured data on the magnetic medium, and terminating the obscuring upon reaching the physical position in the indicator.

Abstract: In one embodiment, a system includes a processor, logic in the processor and/or memory configured to determine a physical position on a magnetic medium that corresponds to an end of encrypted data written over residual unencrypted data, and logic configured to store an indicator of the physical position on at least one of the magnetic medium and a memory coupled thereto. In another embodiment, a method includes determining a physical position on a magnetic medium that corresponds to an end of encrypted data written over residual unencrypted data, storing an indicator of the physical position on at least one of the magnetic medium and a memory coupled thereto.

Abstract: A method, system and computer-usable medium are disclosed for reordering User Data Segment (UDS) lists to reduce seek times when accessing data stored on tape media. A host application sends a list of UDSs to a target tape drive and requests the tape drive to reorder the list to provide better performance. An ordered list of target User data Segments to retrieve from a target tape media is received. Information related to the location of each UDS on the target media is processed to determine its corresponding physical position on the tape media. The resulting physical positions are then processed to generate a reordered UDS list, where the order of the User Data Segments is reordered according to their physical location on the target tape media. The reordered list of User Data Segments is then used to perform seek, reposition and read operations to read User Data Segments from the tape media.

Abstract: A method to erase a magnetic tape, where the magnetic tape is first mounted in a magnetic tape in a tape drive, where that magnetic tape includes a physical beginning of tape (“PBOT”), a physical end of tape (“PEOT”), and information written thereon between the PBOT and the PEOT. The method then establishes one or more critical areas located on the magnetic tape, attempts to erase the information, and determines if each of the one or more critical areas have been erased. In the event each of said one or more critical areas have not been erased, Applicants' method provides an error message.

Abstract: A method to erase a magnetic tape, where the magnetic tape is first mounted in a magnetic tape in a tape drive, where that magnetic tape includes a physical beginning of tape (“PBOT”), a physical end of tape (“PEOT”), and information written thereon between the PBOT and the PEOT. The method then establishes one or more critical areas located on the magnetic tape, attempts to erase the information, and determines if each of the one or more critical areas have been erased. In the event each of said one or more critical areas have not been erased, Applicants' method provides an error message.

Abstract: 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.

Abstract: A method and system are disclosed for efficiently reading and processing multiple data blocks stored in a removable data storage medium within a data storage system, wherein each data block includes a header portion containing selected parameters necessary to identify and process an associated data block, and a data portion. Each data block is accessed within the removable data storage medium utilizing track logic circuitry and then coupled to a data block buffer for temporary storage. A header processing logic circuit is interposed between the track logic circuitry and the data block buffer and is utilized to initiate processing of only the header portion of each data block prior to storage of the data block within the data block buffer. After completion of processing of the header portion of a data block and completion of storage of that data block within the data block buffer, the data block is efficiently processed utilizing selected parameters contained within the header portion.

Abstract: 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.

Abstract: Information bearing signals are recorded in one of a plurality of record formats on one record medium, such as a magnetic tape, magnetic disk, optical disk, and the like. The format selected may be commanded or based upon record lengths, in bytes. When the record length equals or exceeds a predetermined number of bytes, then one record is recorded in each signal block of the record format. When the record length is less than the predetermined number, then a second format is used which inserts several of the records in one of the signal blocks. The signal block and its packets respectively contain indications of formats such that any one of several formats may be used on one record medium and in one signal block having a plurality of variable length packets. Logical indicators, such as format marks, tape marks, and the like, may separate formats used on the storage medium.