摘要:
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.
摘要:
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 2k, and the track rotation value R is equal to 2k−1−1. A corresponding apparatus is also disclosed herein.
摘要:
A longitudinal position (LPOS) word L(n) is encoded with error correction capability. The LPOS word includes a plurality of LPOS symbols L0(n) through Lk(n) calculated as L ( n ) = ∑ i = 0 5 L i ( n ) 14 i and representing a longitudinal position of a magnetic tape relative to a tape head in a tape storage system. A word type is determined in response to at least one of the plurality of LPOS symbols and, in response to the determined word type, at least one formatted symbol F(n) is generated from the plurality of LPOS symbols L(n). At least one parity symbol P(n) is generated from the formatted symbol F(n). The formatted and parity symbols are communicated to a servo channel of the tape storage system to be recorded onto a servo track of the magnetic tape. Adding redundancy to LPOS words provides the capability of correcting multiple bit errors without increasing the LPOS word length.
摘要:
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.
摘要:
Method and apparatus are provided for encoding and decoding rate-(s(K+1)/s(K+1)+1) TCMTR(j,k,t,a) codes, where s is the ECC symbol size in bits and K is the number of unencoded symbols that are interleaved with an (s+1)-bit encoded block at the output of a rate-s/(s+1) encoder that encodes the r-th s-bit symbol. K=m/s−1 where m=s(K+1) is the total number of bits to be encoded. Error propagation is reduced, thus allowing the ECC code to correct errors efficiently. Header error-rate is also reduced by eliminating occurrence of likely error events at the detector output. Although initially an RLL code may be designed for an ECC symbol size of s bits, the RLL encoding of the present invention may be used in conjunction with ECC schemes that utilize symbol sizes other than s bits.
摘要:
The state or condition of a system may be evaluated by comparing a set of selected parameter values, converted into a trial vector, with a number of model or exemplar vectors, each of which was represents a particular state or condition of a sample system. Examples of such conditions may include “good”, “marginal”, “unacceptable”, “worn”, “defective”, or other general or specific conditions. Sets of parameter values from the system are converted into input vectors. Unprocessed vectors are then processed against the input vectors in an artificial neural network to generate the exemplar vectors. The exemplar vectors are stored in a memory of an operational system. During operation of the system, the trial vector is compared with the exemplar vectors. The exemplar vector which is closest to the trial vector represents a state which most closely represents the current state of the system. Thus, a high similarity between the trial vector and an exemplar vector which represent a “good” system is likely to have come from a “good” system.
摘要:
A technique for providing end-to-end data protection while supporting multiple cyclic-redundancy-check (CRC) algorithms includes receiving a data block protected by a first CRC. The first CRC is generated using a first CRC algorithm. The integrity of the data block is checked using the first CRC and the first CRC algorithm. A second CRC for the data block is then computed using a second CRC algorithm different from the first CRC algorithm. The data block, first CRC, and second CRC are stored on a storage medium, such as magnetic tape.
摘要:
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.
摘要:
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.
摘要:
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.