Patent application number | Description | Published |
20080235556 | REVERSE CONCATENATION FOR PRODUCT CODES - A system is provided to encode data for recording onto media whereby modulation and linear constraints from a concatenated code or product code are imposed. A first array of unencoded user data is generated. Each row is modulation encoded to enforce a first modulation constraint; the array is transformed into a second array which is transformed into a third array having predetermined empty locations in each column interleaved with the modulated data. A C2-parity byte is computed for at least some of the empty locations of the third array and a fourth array is generated. C1-parity symbols in each row are computed, generating a fifth array. A second modulation constraint is enforced on each C1-parity symbol in each row of the fifth array, generating a sixth array. The rows of the sixth array are assembled with header and sync fields for recording onto a recording media. | 09-25-2008 |
20080235562 | REVERSE CONCATENATION FOR PRODUCT CODES - Method and computer program product are provided to encode data for recording onto media whereby modulation and linear constraints from a concatenated code or product code are imposed. A first array of unencoded user data is generated. Each row is modulation encoded to enforce a first modulation constraint; the array is transformed into a second array which is transformed into a third array having predetermined empty locations in each column interleaved with the modulated data. A C2-parity byte is computed for at least some of the empty locations of the third array and a fourth array is generated. C1-parity symbols in each row are computed, generating a fifth array. A second modulation constraint is enforced on each C1-parity symbol in each row of the fifth array, generating a sixth array. The rows of the sixth array are assembled with header and sync fields for recording onto a recording media. | 09-25-2008 |
20080256422 | Apparatus for Providing Error Correction Capability to Longitudinal Position Data - A method and apparatus for providing error correction capability to longitudinal position data are disclosed. Initially, data are encoded via a set of even LPOS words and a set of odd LPOS words. The encoded data are then decoded by generating a set of syndrome bits for each of the LPOS words. A determination is then made as to whether or not there is an error within one of the LPOS words based on its corresponding syndrome bits. | 10-16-2008 |
20080256423 | Apparatus for Providing Error Correction Capability to Longitudinal Position Data - A method and apparatus for providing error correction capability to longitudinal position data are disclosed. Initially, data are encoded via a set of even LPOS words and a set of odd LPOS words. The encoded data are then decoded by generating a set of syndrome bits for each of the LPOS words. A determination is then made as to whether or not there is an error within one of the LPOS words based on its corresponding syndrome bits. | 10-16-2008 |
20080284624 | HIGH-RATE RLL ENCODING - An unencoded m-bit data input sequence is divided into a block of n bits and a block of m−n bits. The block of n bits is divided into a first set of n+1 encoded bits, wherein at least one of P1 subblocks of the first set satisfies a G, M and I constraints. The first set of n+1 encoded bits is mapped into a second set of n+1 encoded bits wherein at least one of P2 subblocks of the second set gives rise to at least Q1 transitions after 1/(1+D | 11-20-2008 |
20090027242 | HIGH-RATE RLL ENCODING - An unencoded m-bit data input sequence is divided into a block of n bits and a block of m-n bits. The block of n bits is divided into a first set of n+1 encoded bits, wherein at least one of P1 subblocks of the first set satisfies a G, M and I constraints. The first set of n+1 encoded bits is mapped into a second set of n+1 encoded bits wherein at least one of P2 subblocks of the second set gives rise to at least Q1 transitions after 1/(1+D | 01-29-2009 |
20090207515 | ERROR CORRECTION CAPABILITY FOR LONGITUDINAL POSITION DATA IN A TAPE STORAGE SYSTEM - A longitudinal position (LPOS) word L(n) is encoded with error correction capability. The LPOS word includes a plurality of LPOS symbols L | 08-20-2009 |
20100177420 | REWRITING CODEWORD OBJECTS TO MAGNETIC DATA TAPE UPON DETECTION OF AN ERROR - During a read-after-write operation on magnetic tape, a first SCO is formed which includes two encoded processed user data units and is one of T SCOs in a first SCO set. The user data units are each one of T user data units in first and second user data unit sets, respectively, within the first SCO set. The first SCO set is written to the magnetic tape and is immediately read. When an error is detected in one of the user data units, a second SCO is formed to include the first user data unit and, only if an error is not detected in a user data unit in the other user data unit set, to not include the other user data unit, the second SCO being one of T SCOs in a second SCO set. Then, the second SCO set is rewritten to a later position on the tape later. | 07-15-2010 |
20100177422 | REWRITE-EFFICIENT ECC/INTERLEAVING FOR MULTI-TRACK RECORDING ON MAGNETIC TAPE - For writing data to multi-track tape, a received data set is received and segmented into unencoded subdata sets, each comprising an array having K | 07-15-2010 |
20100180180 | ECC INTERLEAVING FOR MULTI-TRACK RECORDING ON MAGNETIC TAPE - Conventional C2 coding and interleaving for multi-track data tape in LTO-¾ do not support recording data onto a number of concurrent tracks which is not a power of two. Higher-rate longer C2 codes, which do not degrade error rate performance, are provided. An adjustable format and interleaving scheme accommodates future tape drives in which the number of concurrent tracks is not necessarily a power of two. A data set is segmented into a plurality of unencoded subdata sets and parity bytes are generated for each row and column. The parameters of the C2 code include N | 07-15-2010 |
20110197100 | NON-VOLATILE REDUNDANT VERIFIABLE INDICATION OF DATA STORAGE STATUS - A non-volatile redundant verifiable indication of data storage status is provided with respect to data storage operations conducted with respect to removable data storage media, and store the indication with an auxiliary non-volatile memory of the data storage media, such that the indication stays with the media. At least one state value indicating the status of the data storage operation is written to one page of the auxiliary non-volatile memory, and a redundancy check is provided with respect to at least the written state value of the one page of the auxiliary non-volatile memory; and the same state value is written to a second page of the auxiliary non-volatile memory, and a redundancy check is provided with respect to at least the written state value of the second page of the auxiliary non-volatile memory. The redundancy checks indicate the validity of the state values. | 08-11-2011 |
20110219199 | VOLUME COHERENCY VERIFICATION FOR SEQUENTIAL-ACCESS STORAGE MEDIA - A method for determining volume coherency is disclosed herein. Upon completing a first write job to a volume partition, the method makes a copy of a volume change reference (VCR) value associated with the volume. The VCR value is configured to change in a non-repeating manner each time content on the volume is modified. Prior to initiating a second write job to the volume partition, the method retrieves the copy and compares the copy to the VCR value. If the copy matches the VCR value, the method determines that a logical object on the partition was not modified between the first and second write jobs. If the copy does not match the VCR value, the method determines that the logical object on the partition was modified between the first and second write jobs. A corresponding system and computer program product are also disclosed herein. | 09-08-2011 |
20110252290 | INTEGRATED DATA AND HEADER PROTECTION FOR TAPE DRIVES - A method for integrating data and header protection in tape drives includes receiving an array of data organized into rows and columns. The array is extended to include one or more headers for each row of data in the array. The method provides two dimensions of error correction code (ECC) protection for the data in the array and a single dimension of ECC protection for the headers in the array. A corresponding apparatus is also disclosed herein. | 10-13-2011 |
20120033321 | TAPE LAYOUT DESIGN FOR RELIABLE ECC DECODING - A method for physically laying out data on tape is disclosed herein. In one embodiment, such a method includes receiving a data set, wherein the data set includes S sub data sets (SDSs) of fixed size and each SDS includes N codeword interleaves (CWIs). The method further distributes the CWIs for the S SDSs across T tracks on a physical tape medium such that the distances between CWIs of the same SDS are substantially maximized on the physical tape medium. To maximize the distances, the method periodically rotates the tracks within the data set by a track rotation value R, wherein the number of tracks T is equal to 2 | 02-09-2012 |
20120036318 | EFFICIENT REWRITE TECHNIQUE FOR TAPE DRIVES - A method for efficiently rewriting data to tape is disclosed herein. In one embodiment, such a method includes writing a data set to tape, the data set comprising S sub data sets of fixed size, each sub data set comprising N code word interleaves (CWIs). The method further includes reading the data set while writing it to the tape to identify faulty CWIs. While reading the data set, the method buffers the faulty CWIs (such as by storing, identifying, and/or marking the faulty CWIs) for later retrieval. When the end of the data set is reached, the method writes corrected versions of the faulty CWIs to the end of the data set. A corresponding apparatus is also disclosed and claimed herein. | 02-09-2012 |
20120144271 | DECODING ENCODED DATA CONTAINING INTEGRATED DATA AND HEADER PROTECTION - A method for decoding encoded data comprising integrated data and header protection is disclosed herein. In one embodiment, such a method includes receiving an extended data array. The extended data array includes a data array organized into rows and columns, headers appended to the rows of the data array, column ECC parity protecting the columns of the data array, and row ECC parity protecting the rows and headers combined. The method then decodes the extended data array. Among other operations, this decoding step includes checking the header associated with each row to determine whether the header is legal. If the header is legal, the method determines the contribution of the header to the corresponding row ECC parity. The method then reverses the contribution of the header to the corresponding row ECC parity. A corresponding apparatus (i.e., a tape drive configured to implement the above-described method) is also disclosed herein. | 06-07-2012 |
20120210194 | INTEGRATED DATA AND HEADER PROTECTION FOR TAPE DRIVES - A method for integrating data and header protection in tape drives includes receiving an array of data organized into rows and columns. The array is extended to include one or more headers for each row of data in the array. The method provides two dimensions of error correction code (ECC) protection for the data in the array and a single dimension of ECC protection for the headers in the array. A corresponding apparatus is also disclosed herein. | 08-16-2012 |
20120307389 | TRACK-DEPENDENT DATA RANDOMIZATION MITIGATING FALSE VFO DETECTION - A method for randomizing data to mitigate false VFO detection is described. In one embodiment, such a method includes simultaneously receiving multiple input data streams. Each input data stream is associated with a different track on a magnetic tape medium. The input data streams are simultaneously scrambled to produce multiple randomized data streams. The input data streams are scrambled such that different bit patterns are produced in the randomized data streams even where corresponding bit patterns in the input data streams are identical. The randomized data streams are simultaneously written to their associated data tracks on the magnetic tape medium. | 12-06-2012 |
20120307393 | TRACK-DEPENDENT DATA RANDOMIZATION MITIGATING FALSE VFO DETECTION - A method for randomizing data to mitigate false VFO detection is described. In one embodiment, such a method includes simultaneously receiving multiple input data streams. Each input data stream is associated with a different track on a magnetic tape medium. The input data streams are simultaneously scrambled to produce multiple randomized data streams. The input data streams are scrambled such that different bit patterns are produced in the randomized data streams even where corresponding bit patterns in the input data streams are identical. The randomized data streams are simultaneously written to their associated data tracks on the magnetic tape medium. A corresponding apparatus is also described. | 12-06-2012 |
20130055053 | END-TO-END DATA PROTECTION SUPPORTING MULTIPLE CRC ALGORITHMS - A method for providing end-to-end data protection while supporting multiple cyclic-redundancy-check (CRC) algorithms is disclosed. In one embodiment, such a method includes receiving, from a first host device, a data block protected by a first CRC. The first CRC is generated using a first CRC algorithm. The method checks the integrity of the data block using the first CRC and the first CRC algorithm. The method then computes a second CRC for the data block using a second CRC algorithm different from the first CRC algorithm. The method then stores the data block, the first CRC, and the second CRC on a storage medium, such as magnetic tape. A corresponding apparatus is also disclosed. | 02-28-2013 |
20130055054 | END-TO-END DATA PROTECTION SUPPORTING MULTIPLE CRC ALGORITHMS - A method for providing end-to-end data protection while supporting multiple cyclic-redundancy-check (CRC) algorithms is disclosed. In one embodiment, such a method includes receiving, from a first host device, a data block protected by a first CRC. The first CRC is generated using a first CRC algorithm. The method checks the integrity of the data block using the first CRC and the first CRC algorithm. The method then computes a second CRC for the data block using a second CRC algorithm different from the first CRC algorithm. The method then stores the data block, the first CRC, and the second CRC on a storage medium, such as magnetic tape. | 02-28-2013 |
20130229724 | CUSTOMIZING A RANGE OF ACCEPTABLE TAPE DIMENSIONAL STABILITY WRITE CONDITIONS - Described are embodiments of an invention for customizing the range of acceptable write conditions to a tape of a tape cartridge that contracts or expands laterally based on environmental conditions. The tape drive utilizes servo information to determine if the tape has expanded or contracted from the nominal dimension and to determine the magnitude of the expansion or contraction. In the case of expansion, the magnitude of the determined expansion and the stored maximum amount of contraction must be below a predetermined threshold value to allow a write. In the case of contraction, the magnitude of the determined contraction and the stored magnitude of expansion must be below the same predetermined threshold value to allow a write. If the determined magnitude of contraction or expansion is greater than the stored magnitude of contraction or expansion, respectively, then the new extreme is stored. | 09-05-2013 |
20140177088 | CUSTOMIZING A RANGE OF ACCEPTABLE TAPE DIMENSIONAL STABILITY WRITE CONDITIONS - Described are embodiments of an invention for customizing the range of acceptable write conditions to a tape of a tape cartridge that contracts or expands laterally based on environmental conditions. The tape drive utilizes servo information to determine if the tape has expanded or contracted from the nominal dimension and to determine the magnitude of the expansion or contraction. In the case of expansion, the magnitude of the determined expansion and the stored maximum amount of contraction must be below a predetermined threshold value to allow a write. In the case of contraction, the magnitude of the determined contraction and the stored magnitude of expansion must be below the same predetermined threshold value to allow a write. If the determined magnitude of contraction or expansion is greater than the stored magnitude of contraction or expansion, respectively, then the new extreme is stored. | 06-26-2014 |