Data object rewrite to sequential storage media

    公开(公告)号:GB2583040B

    公开(公告)日:2021-06-23

    申请号:GB202009787

    申请日:2018-12-04

    Applicant: IBM

    Abstract: In one embodiment, a method includes writing a data set to a sequential access medium. The method also includes reading the data set after being written in a read-while-write process to identify faulty encoded data blocks, each of the faulty encoded data blocks including at least one faulty codeword. Moreover, the method includes rewriting a correct version of a first of the encoded data blocks in a first encoded data block set to the rewrite area of the sequential access medium selected from a predetermined subset of logical tracks. The predetermined subset of logical tracks includes D1+D2+1 logical tracks. Only one encoded data block from a particular sub data set is rewritten in a single encoded data block set in the rewrite area.

    Low latency lateral decoding of data for retrieval from magnetic tape

    公开(公告)号:GB2558416B

    公开(公告)日:2019-02-27

    申请号:GB201720581

    申请日:2017-12-11

    Applicant: IBM

    Abstract: In one embodiment, a method includes reading a plurality of narrow-spread (NS) codewords from M tracks of a magnetic tape medium using a plurality of read elements, the plurality of NS codewords collectively comprising data logically organized as a predetermined number of two-dimensional arrays. Each two-dimensional array includes a predetermined number of NS codewords positioned orthogonally to a predetermined number of wide-spread (WS) codewords, with a first NS codeword from a first two-dimensional array being read in its entirety from the magnetic tape medium prior to reading a second NS codeword from the first two-dimensional array. The method also includes laterally decoding each NS codeword from the first two-dimensional array read from the M tracks of the magnetic tape medium in succession prior to decoding any WS codewords from the first two-dimensional array. The NS codewords are protected with a stronger encoding than the WS codewords within each two-dimensional array.

    Low latency lateral decoding of data for retrieval from magnetic tape

    公开(公告)号:GB2558416A

    公开(公告)日:2018-07-11

    申请号:GB201720581

    申请日:2017-12-11

    Applicant: IBM

    Abstract: A method includes reading a plurality of narrow-spread (NS) codewords 812 from M tracks of a magnetic tape medium 802 using a plurality of read elements, the plurality of NS codewords collectively comprising data logically organized as a predetermined number of two-dimensional arrays. Each two-dimensional array includes a predetermined number of NS codewords positioned orthogonally to a predetermined number of wide-spread (WS) codewords 810, with a first NS codeword from a first two-dimensional array 804 being read in its entirety from the magnetic tape medium prior to reading a second NS codeword from the first two-dimensional array. The method also includes laterally decoding each NS codeword from the first two-dimensional array read from the M tracks of the magnetic tape medium in succession prior to decoding any WS codewords from the first two-dimensional array. The NS codewords are protected with a stronger encoding than the WS codewords within each two-dimensional array. The lower latency from decoding the NS codewords can be used to drive decision-directed digital front-end functions of read channels such as asymmetry cancellation, adaptive equalization, interpolation and gain adjustment.

    High-density pattern detector for hybrid servo patterns

    公开(公告)号:GB2543898A

    公开(公告)日:2017-05-03

    申请号:GB201614483

    申请日:2016-08-25

    Applicant: IBM

    Abstract: A tape drive includes a controller having logic configured to obtain at least two periodic waveform components of a high density (HD) servo signal. The HD signal being read by a servo reader 716 from a HD pattern written on a servo band of a magnetic tape medium. The logic is also configured to filter the HD servo signal using a number of digital filters 702, 704 and 706 that are configurable to detect waveform components simultaneously read from the magnetic tape medium. Each digital filter being configured to match waveform component parameters and tape velocity. The logic computes a position error signal 724 (PES) based on the filtered HD servo signal. The HD servo pattern may have three periodic waveforms of a low f1, mid f2 and high frequency f3. Each digital filter may be configured to estimate an energy of a periodic waveform component by the Goertzel algorithm.

    Data object rewrite to sequential storage media

    公开(公告)号:GB2583040A

    公开(公告)日:2020-10-14

    申请号:GB202009787

    申请日:2018-12-04

    Applicant: IBM

    Abstract: A method includes writing a data set to a sequential access medium. The method also includes reading the data set immediately after being written to the sequential access medium in a read-while-write process to identify one or more faulty encoded data blocks, each of the one or more faulty encoded data blocks including at least one faulty codeword having symbols at least 10 bits in size. Moreover, the method includes rewriting a first of the one or more faulty encoded data blocks within a first encoded data block set to a particular logical track in the rewrite area of the sequential access medium selected from a predetermined subset of logical tracks. The predetermined subset of logical tracks includes D1+D2+1 logical tracks. Only one faulty encoded data block from a particular sub data set is rewritten in a single encoded data block set in the rewrite area.

    Hybrid servo pattern configurations for magnetic tape

    公开(公告)号:GB2581108A

    公开(公告)日:2020-08-05

    申请号:GB202007886

    申请日:2018-10-25

    Applicant: IBM

    Abstract: A tape drive-implemented method includes: determining a servo band configuration of servo bands on a magnetic tape, using servo readers on a magnetic tape head to read one or more of the servo bands based on the determined servo band configuration, and using information read from the one or more of the servo bands to position the magnetic tape head relative to the magnetic tape. An array of data transducers is positioned along the magnetic tape head, the array extending perpendicular to a direction of travel of the magnetic tape. Moreover, a group of the servo readers is positioned at each end of the array of data transducers, and a distance between each of the immediately adjacent servo readers in each of the groups of servo readers is less than or equal to one third of a prespecified width of each of the servo bands.

Patent Agency Ranking