Abstract: Example apparatus and methods combine erasure coding with data deduplication to simultaneously reduce the overall redundancy in data while increasing the redundancy of unique data. In one embodiment, an efficient representation of a data set is produced by deduplication. The efficient representation reduces duplicate data in the data set. Redundancy is then added back into the data set using erasure coding. The redundancy that is added back in adds protection to the unique data associated with the efficient representation. How much redundancy is added back in and what type of redundancy is added back in may be controlled based on an attribute (e.g., value, reference count, symbol size, number of symbols) of the unique data. Decisions concerning how much and what type of redundancy to add back in may be adapted over time based, for example, on observations of the efficiency of the overall system.

Abstract: A media drive includes a head, a servo signal processing circuit, an actuator and a processor. The head is positioned near a data storage medium, and includes a servo element. The servo signal processing circuit is coupled to the servo element to output a position error signal. The actuator controls a position of the head relative to the data storage medium. The processor communicates with the actuator and the servo signal processing circuit. The processor provides a filtered position error signal to the actuator to compensate for a position displacement between the head and the data storage medium. The filtered position error signal includes a sum of outputs from a first compensation filter and a second compensation filter that is each applied to the position error signal output. The compensation filters attenuate disturbance frequencies that contribute to the position displacement. Each of the compensation filters has a sampling rate relating to the respective disturbance frequency.

Abstract: A method for inhibiting cycle slip in a tape drive having at least three channels that each utilizes a corresponding numerically controlled oscillator includes establishing a reference clock that is based on an output of the numerically controlled oscillators for at least two of the channels, comparing the output of the numerically controlled oscillator for one of the three channels with the reference clock to determine a first channel phase delta value for the one channel, and generating an error signal for the one channel if the channel phase delta value exceeds a threshold phase delta value for the one channel.

Abstract: An apparatus and method for providing adaptive disturbance compensation with multi-rate synchronized sampling is disclosed herein. The dynamic disturbance occurring in a media drive during read/write operations is attenuated using the adaptive disturbance compensation scheme. A plurality of compensation filters are used, each of the compensation filters configured to attenuate a disturbance caused by a particular source within the media drive. Each of the compensation filters is computed based on a sampling rate relevant to the respective disturbances.

Abstract: A head rotator assembly (22) for dynamically compensating for a tape skew of a storage tape that moves over a head (20) in a tape drive (10) comprises a head supporter (230) that is coupled to and supports the head (20), and a supporter mover assembly (232). The supporter mover assembly (232) includes a first actuator (234A) that indirectly rotates a portion of the head supporter (230) about an axis to move the head (20) in an azimuth direction relative to the storage tape to dynamically compensate for the tape skew as the storage tape moves over the head (20). Additionally, the supporter mover assembly (232) can include a first lever (236A) moved by the first actuator (234A) to rotate the portion of the head supporter (230) so that the head (20) moves in the azimuth direction relative to the storage tape to dynamically compensate for the tape skew.

Abstract: A head rotator assembly for positioning a head of a tape drive relative to a storage tape that moves over the head comprises a head supporter and a supporter mover assembly. The head supporter is coupled to and supports the head. The supporter mover assembly includes a first actuator that indirectly rotates a portion of the head supporter about an axis to move the head in an azimuth direction relative to the storage tape as the storage tape moves over the head. The supporter mover assembly can further include a first lever. The first actuator moves the first lever to rotate the portion of the head supporter so that the head moves in the azimuth direction relative to the storage tape.

Abstract: A head rotator assembly (22) for positioning a head (20) of a tape drive (10) relative to a storage tape includes a head supporter (230) and a supporter mover assembly (232). The head supporter (230) is coupled to and supports the head (20). The supporter mover assembly (232) selectively rotates a portion of the head supporter (230) about an axis (241) to move the head (20) in an azimuth direction relative to the storage tape as the storage tape moves over the head (20). The head rotator assembly (22) further includes a controller (16) that controls movement of the supporter mover assembly (232) based at least partially on a positioning signal. The supporter mover assembly (232) can include a first actuator (234A) and a first lever (236A). The first actuator (234A) moves the first lever (236A) to rotate the head supporter (230) so that the head (20) moves in the azimuth direction. The first actuator (234A) can include a piezoelectric element.

Abstract: An apparatus and method for providing adaptive disturbance compensation with multi-rate synchronized sampling is disclosed herein. The dynamic disturbance occurring in a media drive during read/write operations is attenuated using the adaptive disturbance compensation scheme. A plurality of compensation filters are used, each of the compensation filters configured to attenuate a disturbance caused by a particular source within the media drive. Each of the compensation filters is computed based on a sampling rate relevant to the respective disturbances.

Abstract: A method for reducing the number of error events in a transmitted data stream (34) comprises the steps of (i) generating at least a first most probable sequence (16(1)) and a second most probable sequence (16(2)) with a detection algorithm (12); (ii) determining if a first correctable error occurred in the first most probable sequence (16(1)) with an EDC decoder (14); and (iii) determining if a second correctable error occurred in the second most probable sequence (16(2)) with the EDC decoder (14). Additionally, the steps of determining if a first correctable error occurred and determining if a second correctable error occurred can be performed substantially simultaneously. The method can further comprise computing a plurality of path metrics (42) for the transmitted data stream (34); and selecting a first q smallest path metrics out of the first and second most probable sequences (16(1)), (16(2)) with a Q value selector (44).

Abstract: A technique includes in a data storage device, sensing a plurality of data streams from a track of storage media as the media moves in a given direction using a plurality of read elements such that at least one of the read elements is redundant. The technique includes combining the data streams to generate a data stream indicating data read from the track.

Abstract: A head rotator assembly (22) for positioning a head (20) of a tape drive (10) relative to a storage tape includes a head supporter (230) and a supporter mover assembly (232). The head supporter (230) is coupled to and supports the head (20). The supporter mover assembly (232) selectively rotates a portion of the head supporter (230) about an axis (241) to move the head (20) in an azimuth direction relative to the storage tape as the storage tape moves over the head (20). The head rotator assembly (22) further includes a controller (16) that controls movement of the supporter mover assembly (232) based at least partially on a positioning signal. The supporter mover assembly (232) can include a first actuator (234A) and a first lever (236A). The first actuator (234A) moves the first lever (236A) to rotate the head supporter (230) so that the head (20) moves in the azimuth direction. The first actuator (234A) can include a piezoelectric element.

Abstract: A head rotator assembly (22) for positioning a head (20) of a tape drive (10) relative to a storage tape includes a head supporter (230) and a supporter mover assembly (232). The head supporter (230) is coupled to and supports the head (20). The supporter mover assembly (232) rotates a portion of the head supporter (230) about an axis (241) to move the head (20) in an azimuth direction relative to the storage tape as the storage tape moves over the head (20). The head rotator assembly (22) includes a controller (16) that controls movement of the supporter mover assembly (232) based on a positioning signal. The supporter mover assembly (232) can include a first actuator (234A) that moves a first lever (236A) to rotate the head supporter (230) to move the head (20) in the azimuth direction. The first actuator (234A) biases the first lever (236A) to rotate part of the head supporter (230) to move the head in the azimuth direction.

Abstract: A head rotator assembly (22) for positioning a head (20) of a tape drive (10) relative to a storage tape includes a head supporter (230) and a supporter mover assembly (232). The head supporter (230) is coupled to and supports the head (20). The supporter mover assembly (232) rotates a portion of the head supporter (230) about an axis (241) to move the head (20) in an azimuth direction relative to the storage tape as the storage tape moves over the head (20). The head rotator assembly (22) includes a controller (16) that controls movement of the supporter mover assembly (232) based on a positioning signal. The supporter mover assembly (232) can include a first actuator (234A) that moves a first lever (236A) to rotate the head supporter (230) to move the head (20) in the azimuth direction. The first actuator (234A) biases the first lever (236A) to rotate part of the head supporter (230) to move the head in the azimuth direction.

Abstract: An apparatus and method for providing adaptive disturbance compensation with multi-rate synchronized sampling is disclosed herein. The dynamic disturbance occurring in a media drive during read/write operations is attenuated using the adaptive disturbance compensation scheme. A plurality of compensation filters are used, each of the compensation filters configured to attenuate a disturbance caused by a particular source within the media drive. Each of the compensation filters is computed based on a sampling rate relevant to the respective disturbances.

Abstract: In a method of electronically measuring reader/writer offset in a tape drive head, a plurality of sequentially adjacent data tracks are written on a tape with a write head. Error rate information is measured while reading a data track of the plurality of sequentially adjacent data tracks with a read head of the tape drive. A bathtub shaped curve is built from a set of the error rate information which is accumulated by reading the data track at a plurality of offsets of the read head relative to the data track. Offset of the read head relative to the write head is measured by determining an offset of the read head which correlates to a magnetic center of the data track as represented by a center point between edges of the bathtub shaped curve.

Abstract: An actuator assembly (22) for positioning a head (16) of a tape drive (10) relative to a storage tape that moves along a tape path (24) includes a first actuator (228), a second actuator (230) and a controller (26). The actuators (228, 230) move the head (16) in a direction that is substantially perpendicular to the tape path. The first actuator (228) is mounted to the second actuator (230) at a location that is based on a position of a resonance node (680) of the second actuator (230). The controller (26) controls linear positioning of the first actuator (228) and the second actuator (230) relative to the storage tape on a closed-loop basis. The actuators (228, 230) can each include voice coils (246, 260). The second actuator (230) can include two positioner guides (253A, 253B) that are configured in a substantially collinear configuration or in a triangular configuration with the head (16).

Abstract: In a method of electronically measuring reel off-center run-out and reel hub mismatch, tape speed data related to a tape coupled with an operating drive reel is electronically measured. The tape speed data is correlated with drive reel rotation angles. The correlated tape speed data is translated to drive reel hub radii variations with respect to the drive reel rotation angles. The drive reel hub radii variations comprise an operational measure of reel off-center run-out and reel hub mismatch of the drive reel.

Abstract: A circuit for a high-density data recording channel includes a first data detector, a second data detector, one or more multiplexers and a sequence identifier. The first data detector generates a first data detector output, and the second data detector generates a second data detector output. The multiplexers change between a first mode and a second mode to alternately receive the first data detector output and the second data detector output. The sequence identifier receives a data sequence including at least one of a first data sequence, such as VFO data, and a second data sequence, such as random data. The second data sequence includes a greater number of signal levels than the first data sequence. The sequence identifier changes the multiplexers between the first mode and the second mode based on whether the data sequence is the first data sequence or the second data sequence. The data sequence includes a plurality of timing stages.

Abstract: An actuator assembly (22) for positioning a head (16) of a tape drive (10) relative to a storage tape that moves along a tape path (24) includes a first actuator (228), a second actuator (230) and a controller (26). The actuators (228, 230) move the head (16) in a direction that is substantially perpendicular to the tape path. The first actuator (228) is mounted to the second actuator (230) at a location that is based on a position of a resonance node (680) of the second actuator (230). The controller (26) controls linear positioning of the first actuator (228) and the second actuator (230) relative to the storage tape on a closed-loop basis. The actuators (228, 230) can each include voice coils (246, 260). The second actuator (230) can include two positioner guides (253A, 253B) that are configured in a substantially collinear configuration or in a triangular configuration with the head (16).

Abstract: In a method of electronically measuring reader/writer offset in a tape drive head, a plurality of sequentially adjacent data tracks are written on a tape with a write head. Error rate information is measured while reading a data track of the plurality of sequentially adjacent data tracks with a read head of the tape drive. A bathtub shaped curve is built from a set of the error rate information which is accumulated by reading the data track at a plurality of offsets of the read head relative to the data track. Offset of the read head relative to the write head is measured by determining an offset of the read head which correlates to a magnetic center of the data track as represented by a center point between edges of the bathtub shaped curve.