Abstract: In one general embodiment, a method includes receiving a request for a write operation to be performed in a tape drive, determining an expected transaction size of a next write operation, comparing the expected transaction size of the next write operation to each of a first transaction size threshold and a second transaction size threshold in response to receiving the request, determining an optimum a write procedure based at least in part on the comparison, and invoking the optimum write procedure in response to determining the optimum write procedure, wherein the first transaction size threshold is greater than the second transaction size threshold, and wherein the optimum write procedure is selected from the group consisting of: a backhitch write procedure, a same wrap backhitchless flush (SWBF) write procedure, and a recursively accumulating backhitchless flush (RABF) write procedure.

Abstract: A first data group in an access sequence is selected. A distance from a current position of the tape medium is set to be a logical distance value, determined by a calculation function, that is substituted for the physical distance value for the data groups that are located in the specified regions as compared with other data groups located in the alternative specified regions. A second data group in the access sequence is selected. The logical distance value is then determined by multiplying a coefficient based on a physical positioning of each of the data groups in the tape medium, and a percentage of those of the plurality of data groups that have already been selected as the first data group and the second data group.

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: An apparatus, computer readable medium device, and method for controlling transportation of a tape medium. A determination is made whether to execute a backhitch operation in response to writing a data set to tape from the buffer. If not, a determination is made whether a transaction size at which data is transferred from the buffer to the tape is less than a buffer size. If so, then a determination is made of a a new speed and whether a current speed is different from the determined new speed. If so, then a backhitch is initiated.

Abstract: The present invention provides a search method used to search for the reading order of a plurality of recording groups when the plurality of recording groups written on tape are continuously read by a tape drive which manages data on tape in recording units having a fixed data length for each recording. This search method includes the steps of: receiving information on a plurality of tape groups to be read; and sorting the plurality of recording groups to be read so the reading time is shortened. In the sorting step, the time required to sort the plurality of reading groups is reduced by combining two or more recording groups into a single object to be sorted in the sorting step when at least two or more contiguous recording groups have been assigned to the same region or are assigned across adjacent regions among the plurality of regions.

Abstract: According to one embodiment, a method for reading data includes reading a data set repeatedly using different settings until either: a reconstructed data set is sent to a host and/or stored, or a maximum number of rereads has been reached, after each reading of the data set, storing each row to a reserved data buffer that has no errors or errors in the row are correctable using C1-error correction code (ECC) unless a matching row already exists in the reserved data buffer that has fewer corrected errors therein, assembling the data set from the rows stored in the reserved data buffer to form an assembled data set, correcting any remaining errors in the assembled data set using C2-ECC to form the reconstructed data set, and sending the reconstructed data set to the host and/or storing the reconstructed data set.

Abstract: In one embodiment, a method for dynamically allocating a memory includes dividing a memory into a first portion and a second portion in response to detecting an error condition when reading data from a data storage medium. The first portion is allocated for processing normal read and/or write requests. The second portion is allocated for processing error recovery procedure (ERP) requests. In another embodiment, a computer program product for dynamically allocating a memory includes a computer readable storage medium having program code embodied therewith. The program code is readable/executable by a processor to divide, by the processor, a memory into a first portion and a second portion in response to detecting an error condition when reading data from a data storage medium. The first portion is allocated for processing normal read and/or write requests. The second portion is allocated for processing ERP requests.

Abstract: In one embodiment, an apparatus for reading data from a data storage medium includes a processor and logic integrated with and/or executable by the processor, the logic being configured to: read data from a data storage medium, the data including a plurality of data sets, determine that an error condition is detected for a data set read from the data storage medium, determine whether the data set was read from the data storage medium using multiple cut and paste (C/P) error recovery procedure (ERP) (C/P ERP Multi), and when the data set was read from the data storage medium using C/P ERP Multi: continue reading data from the data storage medium normally when the detected error condition has been overcome using C/P ERP Multi; otherwise, continue using C/P ERP Multi to read data from the data storage medium until the error condition is overcome.

Abstract: In one embodiment, a tape drive includes a reserved data buffer and logic integrated with and/or executable by a processor. The logic is configured to read a data set from a medium and store a first portion of the data set to the reserved data buffer in response to a determination that the first portion of the data set is correctable using C2 error correction code (ECC). The logic is also configured to replace any stored row of a non-C2-correctable portion of the data set stored to the reserved data buffer with a corresponding row of the data set read from the medium in response to a determination that the stored row of the non-C2-correctable portion of the data set has an equal amount or more C1-correctable error therein than the corresponding row of the data set read from the medium.

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 of reducing power consumption of a buffer for cache in a tape drive connected to a host in a communicable manner, according to one embodiment, includes detecting a transfer rate of data from the host or to the host, and determining a writing or reading rate of data to or from a tape based on the data transfer rate. A determination is made as to whether predetermined conditions including the data transfer rate, the data writing or reading rate, and a capacity of a buffer are satisfied, where the buffer includes at least two buffer areas. At least one of the buffer areas is selected when the predetermined conditions are satisfied. The selected buffer area is switched to a power saving mode.

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 method includes writing a file into a data partition of a tape medium, writing a pointer of the written file in an index partition and creating a high resolution tape directory (HRTD) including detailed location information of data in a data partition. The method also includes storing the HRTD as part of end of data (EOD) of the index partition in response to a tape cartridge housing the tape medium being unloaded. The storing the HRTD as part of the EOD of the index partition includes requesting movement of the tape medium to the index partition in order to update an index file after changes have occurred to data in the data partition, writing an updated index file into the index partition concurrent to writing an updated HRTD into the EOD of the index partition, and requesting for the tape cartridge to be unloaded.

Abstract: A method of reducing power consumption of a buffer for cache in a tape drive connected to a host in a communicable manner, according to one embodiment, includes detecting a transfer rate of data from the host or to the host, and determining a writing or reading rate of data to or from a tape based on the data transfer rate. A determination is made as to whether predetermined conditions including the data transfer rate, the data writing or reading rate, and a capacity of a buffer are satisfied, where the buffer includes at least two buffer areas. At least one of the buffer areas is selected when the predetermined conditions are satisfied. The selected buffer area is switched to a power saving mode.

Abstract: A first data group in an access sequence is selected. A distance from a current position of the tape medium is set to be a logical distance value, determined by a calculation function, that is substituted for the physical distance value for the data groups that are located in the specified regions as compared with other data groups located in the alternative specified regions. A second data group in the access sequence is selected. The logical distance value is then determined by multiplying a coefficient based on a physical positioning of each of the data groups in the tape medium, and a percentage of those of the plurality of data groups that have already been selected as the first data group and the second data group.

Abstract: Provided are a storage device, method, and program for controlling a tape speed to manage a tape drive buffer. A tape speed is increased from a current tape speed to a target tape speed on a predetermined speed-change timing to control the reading or writing of data between the buffer and the tape medium.

Abstract: In one embodiment, a tape drive system includes a file system adapted for enabling sequential access to data on a tape medium, a file access controller adapted for managing the data, the file access controller including logic adapted for writing a file on the tape medium, logic adapted for writing a pointer of the written file in an index of the tape medium, wherein the pointer is managed by the file access controller, logic adapted for creating a high resolution tape directory (HRTD) including detailed location information of data on the tape medium, and logic adapted for storing the HRTD as part of end of data (EOD) of the index when a tape cartridge housing the tape medium is unloaded. Other systems, methods, and computer program products are described according to more embodiments.

Abstract: In one general embodiment, a method includes receiving a request for a write operation to be performed in a tape drive; determining a capacity margin ratio of the tape drive; determining an optimum a write procedure based at least in part on the capacity margin ratio; and invoking the optimum write procedure in response to determining the optimum write procedure. The optimum write procedure is selected from the group consisting of: a backhitch write procedure, a same wrap backhitchless flush (SWBF) write procedure, and a recursively accumulating backhitchless flush (RABF) write procedure. Systems and computer program products configured to perform similar techniques are also disclosed.

Abstract: A first data group in an access sequence is selected. Those data groups located in specified regions of the tape medium are separated from other data groups located in alternative specified regions of the tape medium. The distance from the current position of the tape medium is set to be a logical distance value, determined by a calculation function, that is substituted for the physical distance value for the data groups that are located in the specified regions as compared with other data groups located in the alternative specified regions. A second data group in the access sequence is selected. The logical distance value is then determined by multiplying a coefficient based on a physical positioning of each of the data groups in the tape medium, and a percentage of those of the plurality of data groups that have already been selected as the first data group and the second data group.

Abstract: In one embodiment, a method is provided for adapting a host transfer rate between a host and a tape drive to a medium transfer rate between the tape drive and a tape. A data compression rate of untransferred data in a buffer of a tape drive is measured. A change in a future host transfer rate is predicated based on the measured compression rate. A host transfer rate between a host and the tape drive is adapted to a medium transfer rate between the tape drive and a tape, based on the predicted change.