Exabyte Corporation

Daniel J Canterbury

Mark R Ayres

Steven Fredrick Hartung

Charles B Klomp

John M Contreras, Deceased

Mark R Ayers

Method and apparatus are provided for re-recording of a frame on magnetic tape (22) when a first recording of the frame is determined to be defective. A frame whose first recording is defective is re-recorded at a spare or reserved location on the tape. The reserved location is dedicated to re-recording of frames, and otherwise cannot have data stored therein. The tape contains a defect map frame (326) which is used to pair physical locations of defective frames with the reserved location whereat the frame is re-recorded. In one embodiment, the reserved location whereat a frame is re-recorded is a reserved physical frame on the same track in which the defective frame is recorded. In another embodiment, the reserved location is on a reserved portion of a track (TG39R) which is not the original track (TG39) upon which the frame is recorded. For embodiments having multi-channel or multi-track frames, the reserved location employs a corresponding plurality of tracks.

Handling defective frames on hard sectored magnetic tape

A magnetic tape drive system (20) records a directory block (CL) at a predetermined position on tape (22), and preferably at the beginning of tape. The directory includes, for each recorded track on tape (22), a data block number of the data block recorded at an end of the track. Preferably a plurality of copies of directory block (CL) are recorded, preferably in reverse direction. Upon receipt of a command to locate a target data block recorded on tape (22), a processor (102) directs a transport controller (82) to position a read element (30R) at the predetermined position on tape (22) for reading the directory. The read element reads the directory from tape (22). The processor (102) compares the target block number with the data block numbers stored in the directory and, in response to the comparison, causes an element positioner (74) via the transport controller (82) to position the read element with respect to the width of the tape (22) so as to read the track upon which the data block having the target data block number is recorded. The track upon which the target data is located is then sequentially searched for the target data block.

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Howell, MI, United States of America

Daniel J Canterbury