A data storage device is disclosed wherein a first host block is written to a first data sector, and when writing a second host block to a second data sector the first host block is read from the first data sector. When the read of the first host block fails, a partial map is generated identifying a location of the second host block in the second data sector, the partial map is stored in a non-volatile memory, and the second host block is written to the second data sector. When a power failure occurs after writing the second host block to the second data sector, an exception entry is updated using the partial map, wherein the exception entry is associated with the first and second host blocks.

A system includes a read/write module and a caching module. The read/write module is configured to access a first portion of a recording surface of a rotating storage device. Data is stored on the first portion of the recording surface of the rotating storage device at a first density. The caching module is configured to cache data on a second portion of the recording surface of the rotating storage device at a second density. The second portion of the recording surface of the rotating storage device is separate from the first portion of the recording surface of the rotating storage device. The second density is less than the first density.

A data storage device is disclosed comprising a first voice coil motor (VCM) comprising a first voice coil configured to actuate a first head over a first disk, and a second VCM comprising a second voice coil configured to actuate a second head over a second disk. The data storage device further comprises a spindle motor configured to rotate the first and second disk, wherein during a power failure the first and second disks rotating causes the spindle motor to generate a back electromotive force (BEMF) voltage. During the power failure, the BEMF voltage is applied to the first VCM and to the second VCM during a first interval. The BEMF voltage is monitored, and when the BEMF voltage falls below a first threshold, the BEMF voltage is disconnected from the first VCM and the second VCM during a second interval.

A data storage device is disclosed wherein a first host block is written to a first data sector, and when writing a second host block to a second data sector the first host block is read from the first data sector. When the read of the first host block fails, a partial map is generated identifying a location of the second host block in the second data sector, the partial map is stored in a non-volatile memory, and the second host block is written to the second data sector. When a power failure occurs after writing the second host block to the second data sector, an exception entry is updated using the partial map, wherein the exception entry is associated with the first and second host blocks.

A storage system includes a final level cache (FLC) module coupled to a storage medium. The storage medium includes a bulk storage portion having a higher data density than a cache storage portion. The cache storage portion is configured as an FLC cache accessed by the FLC module prior to accessing the bulk storage portion. The FLC module receives a request for data from a processor coupled to one or more levels of cache that are separate from the FLC cache. The processor generates the request if the data is not cached in the one or more levels of cache. The FLC module determines whether the data requested is cached in the FLC cache, retrieves the data from the FLC cache if the data is cached in the FLC cache, and retrieves the data from the bulk storage portion if the data is not cached in the FLC cache.

A data storage device is disclosed comprising a first voice coil motor (VCM) comprising a first voice coil, and a second VCM comprising a second voice coil. The first VCM and the second VCM are unloaded during a power failure by measuring a first velocity and a first position of the first VCM and measuring a second velocity and a second position of the second VCM. A BEMF voltage generated by a spindle motor is used to generate a first brake voltage based on the first velocity and the first position, and the BEMF voltage is used to generate a second brake voltage based on the second velocity and the second position. The first brake voltage is applied to the first voice coil, and the second brake voltage is applied to the second voice coil.

A driver device coupled to a winding of an electro-mechanical actuator includes: a power stage driving the winding in a discontinuous mode by alternating conduction on-phases to off-phases, and a sensor circuit sensing a voltage across the winding in an off-phase, wherein, during such an off-phase the voltage across the winding includes a residual voltage which decays to zero. The power stage drives the winding from an on-phase to an off-phase by applying to the winding a reverse current pulse to invert the direction of flow of the current through the winding and produce an oscillation of the residual voltage, whereby the residual voltage includes a zero-crossing point after the current through the winding is exhausted. The sensor circuit senses the voltage across the winding at this zero-crossing point, whereby the voltage sensed across the winding at the zero-crossing point is indicative of the back electromotive force of the winding.

A data storage device is disclosed wherein multiple voice coil motors (VCMs) are unloaded using a back electromotive force (BEMF) voltage generated by a spindle motor. A velocity and position of each VCM is measured, and a priority assigned to each VCM based on the measured velocity and position. During a delay interval, the BEMF voltage is used to apply a first brake voltage to a high priority VCM and to apply a second brake voltage to a low priority VCM, wherein the second brake voltage is lower than the first brake voltage. After the delay interval, the BEMF voltage is used to apply the first brake voltage to the high priority VCM and to apply a third brake voltage to the low priority VCM, wherein the third brake voltage is higher than the second brake voltage.

Illustrative aspects are directed to a data storage device, comprising disks, an actuator mechanism configured to position heads proximate to the disks, and processing devices, including a memory. The processing devices are configured to: receive data with an indicated address for writing the data to a selected disk; read, from the selected disk, a data sector from a location that comprises the indicated address; integrate the received data with a subset of the sector read from the selected disk, thereby generating a new sector that comprises the received data positioned in the new sector in accordance with the indicated address; detect, while the new sector is in the memory and not yet written to the selected disk, a loss of nominal electrical power to the data storage device; and write, in response to detecting the loss of nominal electrical power, the new sector from the memory to a non-volatile cache.

Illustrative aspects are directed to a data storage device, comprising disks, an actuator mechanism configured to position heads proximate to the disks, and processing devices, including a memory. The processing devices are configured to: receive data with an indicated address for writing the data to a selected disk; read, from the selected disk, a data sector from a location that comprises the indicated address; integrate the received data with a subset of the sector read from the selected disk, thereby generating a new sector that comprises the received data positioned in the new sector in accordance with the indicated address; detect, while the new sector is in the memory and not yet written to the selected disk, a loss of nominal electrical power to the data storage device; and write, in response to detecting the loss of nominal electrical power, the new sector from the memory to a non-volatile cache.