Abstract: A computer-implemented method, according to one embodiment, includes: receiving a read request for data stored on a magnetic tape, the data having multiple portions. For each portion of the requested data determined as not being located in a cache, a determination is made as to whether performing a locate command or performing a read command a plurality of times will retrieve the portions of the requested data that are not located in the cache in a shorter amount of time. The command determined to retrieve the portions of the requested data that are not located in the cache in the shorter amount of time are issued to a tape drive. Moreover, the portions of the requested data that are not located in the cache are combined with portions of the requested data that are located in the cache. Furthermore, the combined portions are used to satisfy the read request.

Abstract: There is provided a tape recording apparatus system capable of improving writing performance and maintaining tape recording density, for a multiple data writing request accompanied by a lot of synchronization requests from a host. The system is a tape storage system including two or more tape drives each of which has a tape mounted thereon and is provided with a buffer divided in fixed-length segments, and connected to a host that sends multiple data and a synchronization request at a predetermined timing to these tape drives.

Abstract: In an approach to HRTD recovery by writing the HRTD in a null data set, responsive to receiving a request to write a data set to a magnetic tape, a lead data set of a current wrap of a plurality of wraps of the magnetic tape is written, wherein the lead data set of the current wrap includes a current wrap HRTD that contains one or more directory records for each wrap of the plurality of wraps from a lead wrap of the plurality of wraps through a first prior wrap of the plurality of wraps, and further wherein the first prior wrap immediately precedes the current wrap.

Abstract: An apparatus according to one embodiment includes a controller configured to control writing operations to a magnetic recording tape, and logic integrated with and/or executable by the controller for causing the controller to receive a plurality of records, store datasets associated with the plurality of records in a buffer memory, and write the datasets stored in the buffer memory to the magnetic recording tape in response to a predetermined number of datasets being stored in the buffer memory. For each of the datasets being written, an end longitudinal position indicative of a physical position where the dataset is physically written to the magnetic recording tape is determined. Moreover, for each determined end longitudinal position, the end longitudinal position and an identifier of the associated dataset are stored to a table of a dataset that is to be subsequently written to the magnetic recording tape.

Abstract: An apparatus according to one embodiment includes a controller configured to control writing operations to a magnetic recording tape. The apparatus further includes logic integrated with and/or executable by the controller for causing the controller to write user data to the magnetic recording tape in a user data area of the magnetic recording tape. Furthermore, the logic is integrated with and/or executable by the controller for causing the controller to create a housekeeping data set (HKDS) that includes location information for the user data written in the user data area, and write several copies of the HKDS in a non-user data area of the magnetic recording tape.

Abstract: A computer-implemented method for incrementing a tape write pass (WP) value includes identifying an action that requires incrementing a tape WP value on a magnetic tape storage device. The computer-implemented method further includes, in response to identifying the action that requires incrementing the tape WP value on the magnetic tape storage device: assigning a new tape WP value to a dataset based, at least in part, on a partition number corresponding to the data partition in which the dataset is written to.

Abstract: An apparatus according to one embodiment includes a controller configured to control writing operations to a magnetic recording tape. The apparatus further includes logic integrated with and/or executable by the controller for causing the controller to write user data to the magnetic recording tape in a user data area of the magnetic recording tape. Furthermore, the logic is integrated with and/or executable by the controller for causing the controller to create a housekeeping data set (HKDS) that includes location information for the user data written in the user data area, and write several copies of the HKDS in a non-user data area of the magnetic recording tape.

Abstract: A read error occurs when performing a read with a first read head. It is determined whether a second read head capable of use in a read-while-write operation runs within or outside of a first track. The second read head width defines a verified area on a track. If the second read head runs entirely within the first track, the first read head is positioned within the verified area. If the second read head runs partly outside of the first track, and a portion of the verified area within the first track is wider than the width of the first read head, the first read head is positioned within the portion of the verified area that is within the first track. If the portion is not wider, the first read head is positioned so that a side of the first read head is at a border the first track.

Abstract: Aspects of the present disclosure relate to rewinding a tape medium. Data is written to the tape medium under a first tension. An end data region of the tape medium is identified, where the end data region is not the end of the tape medium. An indication that the tape medium is to be unmounted is received. The position of the tape medium is moved to the end data region. The tape medium is then rewound from the end data region under a second tension, the second tension being lower than the first tension.

Abstract: A computer-implemented method, according to one embodiment, includes: determining whether a first amount of time associated with performing a locate operation to advance a magnetic tape from a current position to a beginning of the requested data is less than a second amount of time associated with performing a number of read operations to advance the magnetic tape from the current position to the beginning of the requested data. In response to determining that the first amount of time is less than the second amount of time, a tape drive is instructed to perform the locate operation. In response to determining that the first amount of time is not less than the second amount of time, the tape drive is instructed to perform the number of read operations. The tape drive is also instructed to discard data read from the magnetic tape while performing the number of read operations.

Abstract: A computer-implemented method, according to one embodiment, includes: receiving a read request for data stored on a magnetic tape, the data having multiple portions. For each portion of the requested data determined as not being located in a cache, a determination is made as to whether performing a locate command or performing a read command a plurality of times will retrieve the portions of the requested data that are not located in the cache in a shorter amount of time. The command determined to retrieve the portions of the requested data that are not located in the cache in the shorter amount of time are issued to a tape drive. Moreover, the portions of the requested data that are not located in the cache are combined with portions of the requested data that are located in the cache. Furthermore, the combined portions are used to satisfy the read request.

Abstract: A computer-implemented method, according to one embodiment, includes: receiving a read request for data stored on a magnetic tape. For each portion of the requested data, an iterative process is performed. In preferred approaches, the iterative process includes: instructing a tape drive to read the portion of the requested data from the magnetic tape, and determining whether a copy of the portion of the requested data is located in a cache. In response to determining that a copy of the portion of the requested data is located in the cache, the tape drive is instructed to discard the portion of the requested data read from the magnetic tape. However, in response to determining that a copy of the portion of the requested data is not located in the cache, the portion of the requested data read from the magnetic tape is received from the tape drive.

Abstract: A computer-implemented method, according to one embodiment, includes: receiving a read request for data stored on a magnetic tape, determining whether a copy of a portion of the requested data is located in a cache, instructing a tape drive to access portions of the requested data determined to not be located in the cache, for each of the portions of the requested data that are not located in the cache, determine whether performing a locate command or performing a read command a plurality of times will retrieve the portions of the requested data in a shorter amount of time, issuing the command determined to retrieve the portions of the requested data in the shorter amount of time, combining the portions of the requested data that are not located in the cache with the portion of the requested data located in the cache, and satisfying the read request.

Abstract: Rolling back data on tape in a file system is provided. A management tape is prepared. The management tape has only index files recorded thereon. The index files contain information about start positions and lengths of corresponding data files recorded on normal tapes. The index files further contain identification information for the normal tapes. A first index file of the management tape is read. The first index file is related to a data file to be rolled back. The first index file is read out from the management tape mounted on a first tape drive. The data file to be rolled back is read out of a first normal tape. The first normal tape is identified based on information in the first index file. The first normal tape is mounted on a second tape drive.

Abstract: A computer-implemented method, according to one embodiment, includes: receiving a read request for data stored on a magnetic tape, determining whether a copy of a portion of the requested data is located in a cache, instructing a tape drive to access portions of the requested data determined to not be located in the cache, for each of the portions of the requested data that are not located in the cache, determine whether performing a locate command or performing a read command a plurality of times will retrieve the portions of the requested data in a shorter amount of time, issuing the command determined to retrieve the portions of the requested data in the shorter amount of time, combining the portions of the requested data that are not located in the cache with the portion of the requested data located in the cache, and satisfying the read request.

Abstract: According to one embodiment, a system includes a controller configured to determine whether a position error signal (PES) is invalid while reading data from a magnetic medium using at least one data channel. An invalid PES indicates off-track reading or a defect in the magnetic medium. The controller is also configured to determine whether a PES value is above a first predetermined threshold in response to a determination that the PES is valid. Moreover, the controller is configured to inject error bits into a data stream in place of corresponding bits of decoded data in response to a determination that the PES is invalid, a determination that the PES value is above the first predetermined threshold, or a determination that the PES is invalid and the PES value is above the first predetermined threshold. Other systems and methods are described in accordance with more embodiments.

Abstract: In one embodiment, a magnetic tape device includes a read control configured to sequentially read records included in data sets from a tape medium into a buffer, and send the records included in the data sets to a host in response to determining that there is no C2 error during reading of the data sets. The read control is also configured to skip a predetermined error recovery process in accordance with a video special mode in response to detecting a C2 error during reading of the data sets.

Abstract: According to one embodiment, a system for processing data includes a controller configured to determine whether a position error signal (PES) is invalid while reading data from a magnetic medium using at least one data channel. The controller is also configured to determine whether a PES value is above a first predetermined threshold in response to a determination that the PES is valid. Moreover, the controller is configured to inject error bits into a data stream in place of corresponding bits of decoded data in response to a determination that the PES is invalid and in response to a determination that the PES value is above the first predetermined threshold. Other systems and methods for processing data are described in accordance with more embodiments.

Abstract: According to one embodiment, a system includes a controller configured to determine whether a position error signal (PES) is invalid while reading data from a magnetic medium using at least one data channel. An invalid PES indicates off-track reading or a defect in the magnetic medium. The controller is also configured to determine whether a PES value is above a first predetermined threshold in response to a determination that the PES is valid. Moreover, the controller is configured to inject error bits into a data stream in place of corresponding bits of decoded data in response to a determination that the PES is invalid, a determination that the PES value is above the first predetermined threshold, or a determination that the PES is invalid and the PES value is above the first predetermined threshold. Other systems and methods are described in accordance with more embodiments.

Abstract: Rolling back data on tape in a file system is provided. A management tape is prepared. The management tape has only index files recorded thereon. The index files contain information about start positions and lengths of corresponding data files recorded on normal tapes. The index files further contain identification information for the normal tapes. A first index file of the management tape is read. The first index file is related to a data file to be rolled back. The first index file is read out from the management tape mounted on a first tape drive. The data file to be rolled back is read out of a first normal tape. The first normal tape is identified based on information in the first index file. The first normal tape is mounted on a second tape drive.