Abstract: A data storage server may store a data packet generated by a client in a first server memory prior to the data packet being migrated to a third server memory of the data storage server by a server controller in response to a server data migration module. The data packet may be moved to satisfy a quality of service agreement between a host and the client. The data packet can be proactively copied to a second server memory by the server controller in response to the migration of the data packet from the first to the third server memories.

Abstract: A data storage server may store a data packet generated by a client in a first server memory prior to the data packet being migrated to a third server memory of the data storage server by a server controller in response to a server data migration module. The data packet may be moved to satisfy a quality of service agreement between a host and the client. The data packet can be proactively copied to a second server memory by the server controller in response to the migration of the data packet from the first to the third server memories.

Abstract: Apparatus and method for enhancing disc drive reliability by applying reduced read bias levels to read elements of a disc drive during an idle mode of operation. A preamplifier driver circuit applies an operational read bias signal of selected, nonzero magnitude to the read element to transduce data from a recording surface during an active mode. Once a predetermined period of inactivity occurs during which host data transfer commands are not processed, the disc drive enters the idle mode and the preamplifier reduces the read bias signal magnitude. The reduced bias level during the idle mode reduces thermal stress and electromigration within the read element while still allowing data to be transduced from the recording surface as the drive performs a dithering operation to move the head to different tracks on the recording surface.

Abstract: Apparatus and method for enhancing disc drive reliability by applying reduced read bias levels to read elements of a disc drive during an idle mode of operation. A preamplifier driver circuit applies an operational read bias signal of selected, nonzero magnitude to the read element to transduce data from a recording surface during an active mode. Once a predetermined period of inactivity occurs during which host data transfer commands are not processed, the disc drive enters the idle mode and the preamplifier reduces the read bias signal magnitude. The reduced bias level during the idle mode reduces thermal stress and electromigration within the read element while still allowing data to be transduced from the recording surface as the drive performs a dithering operation to move the head to different tracks on the recording surface.

Abstract: An apparatus and method for determining the configuration of a disc drive head-disc assembly (HDA). The HDA includes an array of rotatable discs and an actuator adjacent the discs, with the actuator supporting a maximum number of heads in a fully populated configuration and a reduced number of heads in a depopulated configuration. Each head is disposed at a unique head position. A servo circuit determines an impedance of a selected head position having a head when the disc drive is fully populated but not when the disc drive is depopulated. The servo circuit identifies this configuration of the HDA in relation to the determined impedance, and initializes the drive accordingly.

Abstract: Apparatus and method for selecting an optimum gain for an amplifier used to amplify readback signals transduced from a magnetic recording disc in a disc drive. The amplifier is provided with a first value of gain, which is used to amplify a readback signal to generate an amplified readback signal. The amplified readback signal is in turn applied to an automatic gain control circuit comprising a variable gain amplifier. The variable gain amplifier applies a variable gain from a selected range to the amplified readback signal to maintain an amplitude of an output signal provided by the automatic gain control circuit at a nominal amplitude. The acceptability of the first value of gain for subsequent use by the amplifier is determined in relation to a magnitude of the variable gain applied by the variable gain amplifier.

Abstract: Method and apparatus for optimizing the read/write channel error recovery process in a disc drive. An error recovery table comprising a plurality of sequentially ordered corrective operations is provided so that, upon receipt of an error from the disc drive read/write channel, the corrective operations are sequentially performed in an attempt to correct the error. At such time that a selected one of the corrective operations results in the correction of the error, the table is reordered so that the selected one of the corrective operations is advanced in the table sequence, and the reordered table is used upon the occurrence of the next error. Additionally, a series of free retries is performed prior to the operation of the error recovery table.

Abstract: A hard disk drive having a plurality of disks mounted on the rotor of a current limited, electronically commutated dc motor. Windings on the stator of the motor are divided into serially connected run and start sections and first and seconds drive circuits are provided to operate the motor by alternatively enabling the first drive circuit to pass currents serially through the two sections of the winding and enabling the second drive circuit to pass currents through only the run sections of the windings. During spin up of the disk drive to operating speed, the first drive circuit is enabled and the second drive circuit is disabled to drive the disks to the speed at which the back emf limits on the acceleration of the motor using both sections of the windings reduces the acceleration to the maximum acceleration achievable at the current limit using the run sections alone. Spin up is then completed by enabling the second drive circuit and disabling the first drive circuit.