Abstract: A method for correcting data track placement in a magnetic tape drive is provided. The invention comprises writing at least one data track on a magnetic tape, wherein the data track is written in a location determined by tracking a servo track on the tape. The tape drive reads the data track(s) at a plurality of offset positions, wherein each offset position is determined by deviating the servo track a specified distance from a servo reader. An optimal offset position is then determined based on collected read error data versus offset position data. During subsequent write operations, tapes are offset according to the optimal offset position.

Abstract: There are disclosed polyester processes using a pipe reactor and corresponding apparatuses. In particular, there are disclosed processes and corresponding apparatuses including an esterification pipe reactor operated in an upflow or downflow mode, especially in a regime including stratified flow.

Abstract: A system for recording the history associated with writing data onto rewriteable media includes an access head for writing data onto the media and reading data from the media. A drive motor moves the media past the access head. A write formatter formats data into a device block to be written onto the media. A read formatter detects errors in data read from the media. A control unit determines an error recovery procedure based on an error detected in reading the media and enables the write formatter to insert an indication of the error recovery procedure into the device block. The error recovery procedure is then attempted. The process is repeated until either a successful write occurs or the media is determined to be bad.

Abstract: Reducing the gap distance between existing data and appended blocks increases the information density written onto magnetic tape. A narrow gap spacing may be achieved by reading the existing block of data with a read module leading the write module in the tape direction. The end of the existing data is determined from data read by the leading read module. Delaying appending data by a gap period introduces the gap between the existing block of data and the new block of data to be appended. The new block of data is written following the gap and verified by reading with a read module following the write module in the tape direction.

Abstract: Write on the fly certification of magnetic media includes detecting the start of a defect. A sequence of defect matrices is written over the defect with a write element in a read-after-write head. Each defect matrix in the sequence is read with a read element in the read-after-write head. A check is made to determine if an error exists in the data read from each defect matrix. The defect is determined to extend through each defect matrix if an error exists in the read data.

Abstract: A method and system for determining degradation of the tape drive and the tape in a multichannel recording system provides refined definition of correction for data recording statistics. The method and system generate a count signal indicative of the number of data blocks read from multi-track tape having more than a predetermined threshold of data bytes in error. The method and system generate a degradation signal indicative of tape drive and tape degradation if the ratio of corrected data blocks versus the total number of data blocks read from the tape is above a predetermined ratio. The degradation signal is indicative of tape drive degradation if the ratio of data blocks having more than the predetermined number of error data bytes along a single track versus the total number of data blocks read from the tape is above a predetermined ratio.

Abstract: An improved tape storage device having information for converting longitudinal physical positions written in a medium to logical positions used by a tape drive. The conversion information, an offset and an optional maximum physical position value, are stored in one or more locations in the tape storage device. Methods of operating the tape drive are disclosed to determine and store the conversion information in the tape storage device. Another method of operation enables the tape drive to read the conversion information and convert the physical positions to logical positions. The method works for both center loading and end loading medium. Possible numeric rollover of the physical positions is detected by one of several methods including the step values between adjacent physical positions, comparing the logical positions with an upper and lower boundary, and generating a lookup table where the rollover is represented by a wraparound between the top and bottom of the table.

Abstract: A system for recording the history associated with writing data onto rewriteable media includes an access head for writing data onto the media and reading data from the media. A drive motor moves the media past the access head. A write formatter formats data into a device block to be written onto the media. A read formatter detects errors in data read from the media. A control unit determines an error recovery procedure based on an error detected in reading the media and enables the write formatter to insert an indication of the error recovery procedure into the device block. The error recovery procedure is then attempted. The process is repeated until either a successful write occurs or the media is determined to be bad.

Abstract: A system for recording the history associated with writing data onto rewritable media includes an access head for writing data onto the media and reading data from the media. A drive motor moves the media past the access head. A write formatter formats data into a device block to be written onto the media. A read formatter detects errors in data read from the media. A control unit determines an error recovery procedure based on an error detected in reading the media and enables the write formatter to insert an indication of the error recovery procedure into the device block. The error recovery procedure is then attempted. The process is repeated until either a successful write occurs or the media is determined to be bad.

Abstract: A method and a mechanism enabling the method are described to aid in distinguishing new information from old information on a medium. A new variable called a Master Write Pass Count is created for the medium. The Master Write Pass Count is initialized once, advanced on each occasion that new information is written in the medium, and it is never reinitialized or regressed. During each write session the Master Write Pass Count is copied into a Write Pass Count variable associated with each block receiving the new information. The Write Pass Counts may be stored in the header or trailer of the associated block, or external to the block. When the blocks are read from the medium, the Write Pass Counts may be used alone, or in combination with other information associated with the blocks, such as a block identification number, to aid in distinguishing new information from old information.

Abstract: An apparatus and method are disclosed for detecting the velocity of a tape in a tape transport system having a write head and a read head separated by a known distance and formatting the tape using marks. The tape transport system generates a write signal indicating when one of the marks is written to the tape by the write head and a read signal indicating when one of the marks is read from the tape by the read head. An accumulator determines the amount of time between the write signal and the read signal. A velocity detector determines the velocity of the tape based on the time determined by the accumulator and the known distance between the write head and the read head.

Abstract: A method and a mechanism enabling the method are described to aid in distinguishing new information from old information on a medium. A new variable called a Master Write Pass Count is created for the medium. The Master Write Pass Count is initialized once, advanced on each occasion that new information is written in the medium, and it is never reinitialized or regressed. During each write session the Master Write Pass Count is copied into a Write Pass Count variable associated with each block receiving the new information. The Write Pass Counts may be stored in the header or trailer of the associated block, or external to the block. When the blocks are read from the medium, the Write Pass Counts may be used alone, or in combination with other information associated with the blocks, such as a block identification number, to aid in distinguishing new information from old information.

Abstract: A system and method for allowing uni-directional data to be read in the reverse direction as well as the forward direction uses a data buffer to reverse the order of data read from storage media. Data are read from the storage media in the reverse direction and stored in a data buffer. Pointers are set up to track record boundaries of the data storedin the data buffer. The data are read from the data buffer in the opposite direction from which they are stored and sent to a host in the forward direction. Cyclic redundancy checks can be performed as data are read from the storage media in the reverse direction and read from the data buffer in the forward direction.

Abstract: A method and a mechanism enabling the method are described to aid in distinguishing new information from old information on a medium. A new variable called a Master Write Pass Count is created for the medium. The Master Write Pass Count is initialized once, advanced on each occasion that new information is written in the medium, and it is never reinitialized or regressed. During each write session the Master Write Pass Count is copied into a Write Pass Count variable associated with each block receiving the new information. The Write Pass Counts may be stored in the header or trailer of the associated block, or external to the block. When the blocks are read from the medium, the Write Pass Counts may be used alone, or in combination with other information associated with the blocks, such as a block identification number, to aid in distinguishing new information from old information.

Abstract: An apparatus and method are disclosed for detecting the velocity of a tape in a tape transport system having a write head and a read head separated by a known distance and formatting the tape using marks. The tape transport system generates a write signal indicating when one of the marks is written to the tape by the write head and a read signal indicating when one of the marks is read from the tape by the read head. An accumulator determines the amount of time between the write signal and the read signal. A velocity detector determines the velocity of the tape based on said time determined by the accumulator and the known distance between the write head and the read head.

Abstract: The error correction apparatus of this invention maintains a set of pointers which are used to supplement the error correction characters written into the data tracks of the data frame. These pointers consist of indicators stored in a memory that note the location and nature of errors detected in the present data frame or in previous data frames read from the magnetic tape and stored in a buffer memory. The pointer information can be used by the error correction circuitry to determine which tracks typically produce the errors in the data frame. The error correction circuitry can then generate error patterns which can be combined with the data read and reread from the buffer to correct the errors contained therein.