Abstract: A method of calibrating a servo reader and a read/write head for a data storage tape machine that reads and writes data to a data storage tape. The data storage tape has a servo pattern that is recorded on the tape in a known location. The servo pattern is used to provide precise position information for the data storage tape. According to the method, data is recorded on the data storage tape and the location of the data storage track is read. The location of the data storage tape is compared to the known location of the servo pattern to establish a reader offset value. The data storage tape machine is updated based upon the reader offset value to adjust the position of the read/write head.

Abstract: An improved format is disclosed for storing a randomized data block in a storage device. The data block format includes a data field, an identifier (ID) field for storing an identifier that identifies data stored in the data field, and a randomizer seed field for storing a randomizer seed. An error check character generator generates an ID field error check character utilizing said identifier. The randomizer seed includes the ID field error check character.

Abstract: A Viterbi decoder is used to provide erasure information to a symbol based decoder. In a preferred embodiment, a Viterbi decoder is used to provide either minimum distance path metric information or path probability information, which is summed over a symbol window to derive erasure information for the symbol based decoder.

Abstract: In a tape drive for storing and retrieving information to and from a media, a system for optimizing write performance includes a tape head and a controller. The tape head may include a write element. The controller may be for optimizing write performance in response to at least one media information signal that is stored on a media cartridge.

Abstract: A drive and method of identifying write velocity during reading are provided. When a track is being read, the data signal is processed prior to determining the data stream to identify the velocity with which the track data were written. The read channel is adjusted based on the identified velocity to compensate for write channel transfer function variation.

Abstract: Servo tracks for magnetic tape storage are written using two opposite polarities, rather than the one polarity normally used in servo tracks. Timing continues to be performed using only pattern members of like polarity, due to physical restraints, but the use of two polarities allows additional information to be encoded in the pattern more efficiently.

Abstract: In a magnetic recording device, a system and method for correcting errors in decoding a read data input signal. The system and method include multiple decoding channels, each channel processing the read data input signal and generating an output signal, where the output signal includes a data signal when no error is detected, and an error detection code when an error is detected. The system and method also include multiple error correction code (ECC) decoders, each decoder associated with and receiving the output signal of one of the channels and generating a corrected data signal when the received output signal is an error detection code and the error is correctable. The system and method further include a controller for selecting from the decoders one of the corrected data signals.

Abstract: A method and system are provided for dynamically shortening a number of error correction codewords to correspond to an amount of user data to be recorded on a recording medium. The system and method determine in advance that the number of bytes of user data will only fill a portion of a codeword matrix, and automatically shortens the size of ECC word segments to match the actual user data fill. This allows an ECC interleave to be completed with only a partial fill of the matrix, thereby reducing the required number of recording passes and associated processing time.

Abstract: A tape drive and method of identifying write velocity during reading are provided. When a track is being read, a lead-in code of the data signal is processed prior to determining the data stream. The lead-in code identifies the velocity with which the track data were written. The equalization/detection channel is adjusted based on the identified velocity to compensate for write channel transfer function variation. The lead-in code is coded in a way that is reasonably immune to write channel transfer function variation such that the lead-in code is comprehended prior to adjusting the equalization/detection channel.

Abstract: An asynchronous method for locating individual blocks of data in a tape drive, without having to read the blocks of data is provided. The invention comprises placing an ID mark adjacent to the data blocks and inter-block gaps on the tape. The ID mark contains a small amount of information about the next respective data block on the tape. The ID mark is encoded such that the same detection mechanism that detects the inter-block gap can also retrieve the ID mark information, without having to process the entire block of data associated with a particular ID mark. The ID mark is symmetrical such that it can be detected and decoded in the forward and backward direction, allowing the tape drive to find a desired block of data by searching either forward or backward, even when the magnetic tape uses a unidirectional data format.

Abstract: A method, apparatus, and computer instructions for writing data to a magnetic media. A first frequency is written on a first track on the magnetic media on a first track width. A second frequency is written on the first track in which a combination of the first frequency and the second frequency encodes a bit of data on the first track. An erase pattern is created on a second track on the magnetic media, the second track being adjacent to the first track in which the bit of data on the first track is readable by a tape drive system having a second track width wider than the track width of the first track.

Abstract: A system and method for recovering from write errors during writing of a moving storage medium suspend write current while allowing the storage medium to continue moving. The system and method continue to format data for writing while the write current is suspended and resequence the data for subsequent storage. Information is recorded to distinguish previously written data from current data with error correction pointers adjusted accordingly. Write errors may be detected in a track following streaming tape system based on data errors from a read back check or based on positioning errors of a read/write head servo system, for example. By allowing the storage medium to continue moving through the error event, the system and method improve speed, capacity utilization, and throughput of the storage and retrieval process.

Abstract: A system and method for decoding magnetic media. Parallel decoders, each with a different equalization magnitude, are used to decode a read signal. A Viterbi metric is used to determine the direction and magnitude of equalization shift that best compensates for a systematic separation, such as pole tip recession. If optimal equalization has changed, the equalization coefficients of the decoders is shifted to compensate.

Abstract: A method, computer program product, and data processing system for recovering corrupted data in a multi-track storage medium, such as magnetic tape, using a Reed-Solomon or other similar error correcting code system, is disclosed. A correction history keeping a tally of actual corrected instances of corruption in the storage medium is established. The “N” tracks requiring the greatest number of actual error corrections are designated as erasures. Any errors in the remaining tracks must be found on an individual basis before being corrected.

Abstract: A system and method for recovering from write errors during writing of a moving storage medium suspend write current while allowing the storage medium to continue moving. The system and method continue to format data for writing while the write current is suspended and resequence the data for subsequent storage. Information is recorded to distinguish previously written data from current data with error correction pointers adjusted accordingly. Write errors may be detected in a track following streaming tape system based on data errors from a read back check or based on positioning errors of a read/write head servo system, for example. By allowing the storage medium to continue moving through the error event, the system and method improve speed, capacity utilization, and throughput of the storage and retrieval process.

Abstract: A method, computer program product, and data processing system for recovering corrupted data in a multi-track storage medium, such as magnetic tape, using a Reed-Solomon or other similar error correcting code system, is disclosed. A correction history keeping a tally of actual corrected instances of corruption in the storage medium is established. The “N” tracks requiring the greatest number of actual error corrections are designated as erasures. Any errors in the remaining tracks must be found on an individual basis before being corrected.

Abstract: A method and system are provided for dynamically shortening a number of error correction codewords to correspond to an amount of user data to be recorded on a recording medium. The system and method determine in advance that the number of bytes of user data will only fill a portion of a codeword matrix, and automatically shortens the size of ECC word segments to match the actual user data fill. This allows an ECC interleave to be completed with only a partial fill of the matrix, thereby reducing the required number of recording passes and associated processing time.

Abstract: In a magnetic recording device, a system and method for correcting errors in decoding a read data input signal. The system and method include multiple decoding channels, each channel processing the read data input signal and generating an output signal, where the output signal includes a data signal when no error is detected, and an error detection code when an error is detected. The system and method also include multiple error correction code (ECC) decoders, each decoder associated with and receiving the output signal of one of the channels and generating a corrected data signal when the received output signal is an error detection code and the error is correctable. The system and method further include a controller for selecting from the decoders one of the corrected data signals.

Abstract: A method of generating an encoded signal from a sequential stream of digital data, where the encoded signal has a non-power carrying null state and a power carrying active state with two opposing polarities. Logical one bits are distinguished from logical zero bits by inverting the encoded signal's polarity at the start of only the logical one bits. The encoded signal is set to the active state during a bit set-up period before, and held in the active state during a bit hold period after each polarity inversion. At other times the encoded signal is set to the null state. The method may include the addition of equalization pulses during strings of consecutive logical zero bits to keep the encoded signal from remaining in the null state for extended periods. Each equalization pulse may be preceded by an equalization set-up period and followed by an equalization hold period where the encoded signal is in the active state.

Abstract: A servo stripe pattern for determining the longitudinal position of the tape with respect to the tape head. A data field on each frame of the servo pattern includes a digital one or a zero. An adjacent series of data fields are arranged in a predetermined sequence defining synchronization and position count fields. The position count field allows the tape controller to accurately determine where, along the length of the tape, the tape head is currently positioned.