According to one embodiment, a disk device includes a housing including a base with a bottom wall, a drive motor including a pivot erected on the bottom wall and a hub rotatably supported around the pivot, ten or more magnetic disks attached to the hub and stacked on a flange of the hub, and spacer rings attached to the hub and each disposed between each respective adjacent pair of two magnetic disks. A number of the spacer rings is one less than the magnetic disks. At least one spacer ring has a thickness different from that of the other spacer rings, and a difference between a maximum thickness and a minimum thickness of the spacer rings is 0.01 mm or more and 0.09 mm or less.

According to one embodiment, a disk device includes a housing including a base with a bottom wall, a drive motor including a pivot erected on the bottom wall and a hub rotatably supported around the pivot, ten or more magnetic disks attached to the hub and stacked on a flange of the hub, and spacer rings attached to the hub and each disposed between each respective adjacent pair of two magnetic disks. A number of the spacer rings is one less than the magnetic disks. At least one spacer ring has a thickness different from that of the other spacer rings, and a difference between a maximum thickness and a minimum thickness of the spacer rings is 0.01 mm or more and 0.09 mm or less.

The disk device according to one embodiment includes magnetic disks, a magnetic head, a ramp, and a suspension. The suspension includes a sliding portion provided on a load beam. The suspension rotates about a second rotation axis between a load position and an unload position. The ramp includes a wall and a protrusion. The wall has a first support surface that supports the sliding portion when the suspension is located in the unload position. The protrusion includes a second support surface and an intermediate portion. The second support surface faces the magnetic head when the suspension is located in the unload position. The intermediate portion is located between the wall and the second support surface. The intermediate portion includes a first portion and a second portion. The second portion is located between the first portion and the first support surface in the radial direction of the second rotation axis.

According to one embodiment, a magnetic disk apparatus is provided with a magnetic disk, a buffer memory, and a control circuit. The magnetic disk has plural bands, each of which is a storage area in which data is written by the method of SMR. The control circuit receives a read request from outside. If the data requested to be read is first data of an update target stored in a first band among plural bands, the control circuit reads the first data from the first band, stores the first data in a buffer memory, and updates the first data in the buffer memory. Then, the control circuit transmits the first data in the buffer memory to the outside and writes the first data in the buffer memory to one of the plural bands.

According to one embodiment, a magnetic disk apparatus is provided with a magnetic disk, a buffer memory, and a control circuit. The magnetic disk has plural bands, each of which is a storage area in which data is written by the method of SMR. The control circuit receives a read request from outside. If the data requested to be read is first data of an update target stored in a first band among plural bands, the control circuit reads the first data from the first band, stores the first data in a buffer memory, and updates the first data in the buffer memory. Then, the control circuit transmits the first data in the buffer memory to the outside and writes the first data in the buffer memory to one of the plural bands.

According to an embodiment, a magnetic disk device includes a magnetic disk, a magnetic head that accesses the magnetic disk, a motor that moves the magnetic head, a ramp, a motor driver, and a processor. When a voltage value of a power supply voltage falls below a first threshold, the motor driver starts a retract operation of retracting the magnetic head to the ramp by controlling a voltage applied to the motor. When the voltage value of the power supply voltage falls below a second threshold larger than the first threshold, the processor transmits an instruction related to applying a brake to the movement of the magnetic head to the motor driver.

A disk device includes a magnetic disk, a magnetic head configured to read information from and write information to the magnetic disk, a housing having a mounting space in which the magnetic disk and the magnetic head are mounted, a substrate, and a sensor. The housing includes a wall and a hole extending therethrough to the mounting space. The substrate is attached to an outer side of the wall and sealing the hole. The sensor is mounted on the substrate.

A disk device includes a magnetic disk, a magnetic head configured to read information from and write information to the magnetic disk, a housing having a mounting space in which the magnetic disk and the magnetic head are mounted, a substrate, and a sensor. The housing includes a wall and a hole extending therethrough to the mounting space. The substrate is attached to an outer side of the wall and sealing the hole. The sensor is mounted on the substrate.

A disk device includes magnetic disks, ramps, suspensions, and magnetic disks. The magnetic disks are arranged above a housing bottom and configured to be rotated around a first rotation axis. The ramps are arranged above the housing bottom. The suspensions are configured to be rotated around a second rotation axis parallel to the first rotation axis, The magnetic heads are mounted on the suspensions, respectively. Each of the suspensions is configured to be rotated around the second rotation axis from a first position above or below one of the magnetic disks to a second position on one of the ramps. The plurality of ramps includes a first ramp and a second ramp that is above the first ramp. An inner end of the second ramp is closer to the first rotation axis than is an inner end of the first ramp.

A disk device includes magnetic disks, ramps, suspensions, and magnetic disks. The magnetic disks are arranged above a housing bottom and configured to be rotated around a first rotation axis. The ramps are arranged above the housing bottom. The suspensions are configured to be rotated around a second rotation axis parallel to the first rotation axis, The magnetic heads are mounted on the suspensions, respectively. Each of the suspensions is configured to be rotated around the second rotation axis from a first position above or below one of the magnetic disks to a second position on one of the ramps. The plurality of ramps includes a first ramp and a second ramp that is above the first ramp. An inner end of the second ramp is closer to the first rotation axis than is an inner end of the first ramp.