Managing unexpected shutdown in a disk drive with multiple actuators and controllers

A method comprising:

• determining an event that indicates unexpected shutdown of a hard disk drive comprising first and second controllers that control respective first and second independently-operable actuators, each of the actuators comprising one or more heads that access one or more spinning disks of the hard disk drive;
• while receiving power for the hard disk drive via back-electromotive force of a motor driven by the one or more spinning disks in response to the event, performing a shutdown procedure comprising:
• causing the first and second controllers to independently move the respective first and second actuators to safe positions, a timing of the movement of the first and second actuators being coordinated to prevent a spike in electrical load that could cause a voltage of the power provided by the motor to fall below a threshold;
• and
• in response to determining the first and second actuators are in the safe positions, causing write cache data associated with the first and second controllers to be written to a nor-volatile memory.

An apparatus comprising:

• a first and second system on a chip (SoC) that control respective first and second independently-operable actuators, each of the actuators comprising one or more heads that access one or more spinning disks of the apparatus;
• one or more data busses that facilitate communication between the first and second SoC;
• and
• one or more power devices coupled to the first and second SoC and operable to:
• determine an event that indicates unexpected shutdown of the apparatus;
• and
• power the apparatus via back-electromotive force of a motor driven by the one or more spinning disks in response to the event;
• the first and second SoC and the one or more power devices operable to perform a shutdown procedure while receiving the power via the back-electromotive force, the shutdown procedure comprising:
• independently moving the respective first and second actuators to safe positions;
• and
• in response to determining the first and second actuators are in the safe positions, causing write cache data associated with the first and second SoC to be written to a non-volatile memory.