# Patent

## Title
Method and apparatus for servicing host commands by a disk drive

## Abstract

A disk drive including a disk configured to spin at a target spin speed, a servo core configured to access the disk, a first non-volatile memory configured to store a first initialization firmware, a second non-volatile memory configured to store a second initialization firmware, a first volatile memory, a second volatile memory, a non-volatile memory core configured to access the first non-volatile memory, and a main core. The main core is configured to load the second initialization firmware from the second non-volatile memory to the second volatile memory concurrently with the loading of the first initialization firmware from the first non-volatile memory to the first volatile memory by the non-volatile memory core, control the servo core to initiate spinning of the disk, and communicate with the non-volatile memory core to service host commands from the first non-volatile memory when the disk is not spinning at the target spin speed.

## Background
BACKGROUND
A disk drive is commonly used to store data in computers, databases, digital video recorders, and other devices. The disk drive may write data to and read data from a disk in response to write/read commands from a host that uses the disk for data storage. However, to access the disk, the disk generally needs to be spinning at a certain speed. When the disk drive is initially powered up, this entails starting to spin the disk from a state of rest to the desired speed.
Thus, before the disk drive is able to service host commands, the disk drive waits until the disk goes from a state of rest to spinning at the desired speed. This in turn delays a time at which a user can use the disk drive and any device which includes the disk drive.



BRIEF DESCRIPTION OF THE DRAWINGS
The features and advantages of the present embodiments of the present invention will become more apparent from the detailed description set forth below when taken in conjunction with the drawings, wherein:
FIG. 1 depicts a disk drive including a main core, a servo core, and a non-volatile memory core according to an embodiment of the present invention;
FIG. 2 depicts a process according to an embodiment of the present invention;
FIG. 3 depicts a process according to an embodiment of the present invention; and
FIG. 4 depicts a process according to an embodiment of the present invention.



DETAILED DESCRIPTION
In the following detailed description, numerous specific details are set forth to provide a full understanding of the present invention. It will be apparent, however, to one ordinarily skilled in the art that the present invention may be practiced without some of these specific details. In other instances, well-known structures and techniques have not been shown in detail to avoid unnecessarily obscuring the present invention.
In an embodiment, as seen in FIG. 1, a disk drive 100 includes a disk 60, a head 50 connected to a distal end of an actuator arm 25, a main core 104, a servo core 106, a non-volatile memory core 108, a first non-volatile memory 110, a second non-volatile memory 112, a first volatile memory 114, a second non-volatile memory 116, a non-volatile memory controller 118, and a disk controller 120.
In an embodiment, the main core 104 and the servo core 106 are part of the disk controller 120, while the non-volatile memory core 108 is part of the non-volatile memory controller 118. As seen in FIG. 1, the disk controller 120 and the non-volatile memory controller 118 are separate from each other. In an embodiment, the disk controller 120 and the non-volatile memory controller 118 are virtually separate from each other. In another embodiment, the disk controller 120 and the non-volatile memory controller 118 are located on separate system on chips (“SOC”).
The actuator arm 25 is rotated about a pivot by a voice coil motor (VCM) 20 to position the head 50 radially over the disk 60. The disk drive 100 also includes a spindle motor (not shown) for rotating the disk during read/write operations.
The disk 60 comprises a number of radially spaced, concentric tracks 130. Each track 130 may be divided into a number of sectors 140 that are spaced circumferentially along the track 130. The sectors may be used to store user data and other information. In an embodiment, the disk 60 can store a first data for servicing host commands. The disk 60 may also comprise a plurality of angularly spaced servo wedges 220-22N, each of which may include embedded servo information that can be read from the disk 60 by the head 50 to determine the position of the head 50 over the disk 60.
For example, each servo wedge 220-22N may include a pattern of alternating magnetic transitions (servo burst), which may be read from the disk 60 by the head 50 and processed by the controller 120 to estimate the position of the head 50 relative to the disk 60. The angular spacing between the servo wedges 220-22N may be uniform, as shown in the example in FIG. 1.
In an embodiment, the servo core 106 is configured to initiate spinning of the disk 60. Furthermore, the servo core 106 can be configured to access data stored on the disk 60 and can be controlled, for example, by the main core 104. Data on the disk 60 can be accessed, for example, when the disk 60 spins at a target spin speed. The target spin speed can be a speed which the disk spins at where data can be safely and reliably accessed from the disk 60.
In an embodiment, the first non-volatile memory 110 stores a first initialization firmware, while the second non-volatile memory 112 stores a second initialization firmware. In an embodiment, the first non-volatile memory 110 also stores second data for servicing host commands. In one embodiment, the second data for servicing host commands is identical to the first data for servicing host commands. In another embodiment, the second data for servicing host commands is a portion of the first data for servicing host commands.
In an embodiment, the first non-volatile memory 110 is a NAND memory, such as a NAND flash memory. Furthermore, in an embodiment, the second non-volatile memory 112 is a serial flash memory or a NAND memory, such as a NAND flash memory. In an embodiment, the first non-volatile memory and the second non-volatile memory are part of a same memory. In an embodiment, the non-volatile memory core 108 accesses the first volatile memory 114, the first non-volatile memory 110, and the main core 104, while the main core 104 accesses the second volatile memory 116, the second non-volatile memory 112, the servo core 106, and the non-volatile memory core 108.
For example, upon power up, the non-volatile memory core 108 can load the first initialization firmware from the first non-volatile memory 110 to the first volatile memory 114. Similarly, upon power up, the main core 104 can load the second initialization firmware from the second non-volatile memory 112 to the second volatile memory 116 concurrently with the loading of the first initialization firmware from the first non-volatile memory 110 to the first volatile memory 114 by the non-volatile memory core 108.
In an embodiment, the first volatile memory 114 is located in the non-volatile memory core 108. In another embodiment, the first volatile memory 114 is located outside the non-volatile memory core 108 and is coupled to the non-volatile memory core 108. In an embodiment, the second volatile memory 116 is a double data rate (“DDR”) memory.
After the first initialization firmware has been loaded, the main core 104 can communicate with the non-volatile memory core 108 to enable the non-volatile memory core to service host commands from a host. In an embodiment, the main core 104 communicates with the non-volatile memory core 108 to service host commands from the host prior to the disk 60 spinning at the target spin speed. However, after the disk 60 is spinning at the target spin speed, the main core 104 can service host commands from the host using the disk 60 or the first non-volatile memory 110. In an embodiment, the main core 104 accesses the disk 60 using the servo core 106, while the main core 104 accesses the non-volatile memory 110 using the non-volatile memory core 108.
FIG. 2 depicts a process according to an embodiment of the present invention. FIG. 2 depicts, for example, a timeline of the process. In Step 202, the first initialization firmware is loaded. For example, the non-volatile memory core 108 can load the first initialization firmware from the non-volatile memory 110 to the first volatile memory 114. In Step 204, the second initialization firmware is loaded. For example, the main core 104 can load the second initialization firmware from the second non-volatile memory 112 to the second volatile memory 116. In an embodiment, Steps 202 and 204 are performed concurrently. That is, the main core 104 can load the second initialization firmware from the second non-volatile memory 112 to the second volatile memory 116 concurrently with the loading of the first initialization firmware from the first non-volatile memory 110 to the first volatile memory 114 by the non-volatile memory core 108.
In Step 206, the servo core 106 is controlled to initiate spinning of the disk 60. For example, the main core 104 can control the servo core 106 to initiate spinning of the disk 60. In Step 208, the servo core is initialized. For example, upon receiving the command from the main core 104 to initiate spinning of the disk 60, the servo core 106 can be initialized. In Step 210, the disk 60 starts to spin. For example, after initializing of the servo core 106, the servo core 106 can initiate spinning of the disk 60.
In Step 212 the non-volatile memory core 108 communicates with the main core, while in Step 214 the main core 104 communicates with the non-volatile memory core 108 to enable the non-volatile memory core 108 to service host commands. For example, the non-volatile memory core 108 and the main core 104 can communicate with each other in preparation for servicing host commands using the first non-volatile memory 110 when the disk 60 is not spinning at the target spin speed.
In Step 216, the main core 104 posts a drive ready status to a host. For example, the main core 104 can post a HDD ready signal such as 0x5001 to a host. In Step 218 the main core 104 services host commands. For example, the main core 104 services the host commands using the first non-volatile memory 110 when the disk 60 is not spinning at the target spin speed. In an embodiment, the main core 104 services the host commands using the second data for servicing host commands stored in the first non-volatile memory 110.
In Step 220, the main core 104 determines whether there is a need to access the disk 60. For example, the main core 104 may need to access the disk 60 when the first data for servicing host commands stored on the disk 60 is required to service the host commands instead of the second data for servicing host commands stored in the first non-volatile memory 110. If there is no need to access the disk 60, the process repeats Step 218 until there is the need to access the disk 60.
When there is a need to access the disk 60, the process proceeds to Step 222. In Step 222, the main core 104 waits for the disk 60 to spin at a target spin speed. In Step 224 the disk 60 is spinning at a target spin speed. In Step 226, the servo task loop begins. For example, the servo core 106 implements the servo task loop.
In Step 228, the disk initialization is complete. In Step 230, the main core 104 services host commands with the disk 60 spinning at the target spin speed. For example, the main core 104 can service host commands using both the disk 60 and the first non-volatile memory 110. In an embodiment, the main core 104 services host commands using just the disk 60.
FIG. 3 depicts a process according to an embodiment of the present invention. The process in FIG. 3 is similar to the process in FIG. 2, except that the main core 104 waits to control the servo core 106 to initiate spinning of the disk 60 until the main core 104 receives a host command which cannot be serviced using the first non-volatile memory 110, but instead needs to be serviced using the disk 60. Thus, Step 206 is located below Step 220. Since the remaining steps in FIG. 3 are substantially similar to the steps in FIG. 2, a description of the remaining steps will not be repeated.
FIG. 4 depicts a process according to an embodiment of the present invention. In Step 402, the first initialization firmware is loaded from the first non-volatile memory 112 to the first volatile memory 114 using a non-volatile memory core 108.
In Step 404, the second initialization firmware is loaded using the main core 104 from the second non-volatile memory 112 to the second volatile memory 116 concurrently with the loading of the first initialization firmware from the first non-volatile memory 110 to the first volatile memory 114 by the non-volatile memory core 108.
In Step 406, the servo core 106 is controlled to initiate spinning of the disk 60. For example, the main core 104 can control the servo core 106 to initiate spinning of the disk 60. In Step 408, the main core 104 communicates with the non-volatile memory core 108 to enable the non-volatile memory core to service host commands from the first non-volatile memory 110 when the disk 60 is not spinning at a target spin speed. For example, the main core 104 can communicate with the non-volatile memory core 108 to enable the non-volatile memory core 108 to service host commands from the first non-volatile memory 110 when the disk 60 is not spinning at a target spin speed.
Those of ordinary skill would appreciate that the various illustrative logical blocks, modules, and algorithm steps described in connection with the examples disclosed herein may be implemented as electronic hardware, computer software, or combinations of both. Furthermore, the present invention can also be embodied on a machine readable medium causing a processor or computer to perform or execute certain functions.
To clearly illustrate this interchangeability of hardware and software, various illustrative components, blocks, modules, circuits, and steps have been described above generally in terms of their functionality. Whether such functionality is implemented as hardware or software depends upon the particular application and design constraints imposed on the overall system. Skilled artisans may implement the described functionality in varying ways for each particular application, but such implementation decisions should not be interpreted as causing a departure from the scope of the disclosed apparatus and methods.
The various illustrative logical blocks, units, modules, and circuits described in connection with the examples disclosed herein may be implemented or performed with a general purpose processor, a digital signal processor (DSP), an application specific integrated circuit (ASIC), a field programmable gate array (FPGA) or other programmable logic device, discrete gate or transistor logic, discrete hardware components, or any combination thereof designed to perform the functions described herein. A general purpose processor may be a microprocessor, but in the alternative, the processor may be any conventional processor, controller, microcontroller, or state machine. A processor may also be implemented as a combination of computing devices, e.g., a combination of a DSP and a microprocessor, a plurality of microprocessors, one or more microprocessors in conjunction with a DSP core, or any other such configuration.
The steps of a method or algorithm described in connection with the examples disclosed herein may be embodied directly in hardware, in a software module executed by a processor, or in a combination of the two. The steps of the method or algorithm may also be performed in an alternate order from those provided in the examples. Certain steps may be omitted, divided into additional steps, and/or combined into fewer steps. A software module may reside in RAM memory, flash memory, ROM memory, EPROM memory, EEPROM memory, registers, hard disk, a removable disk, a CD-ROM, or any other form of storage medium known in the art. An exemplary storage medium is coupled to the processor such that the processor can read information from, and write information to, the storage medium. In the alternative, the storage medium may be integral to the processor. The processor and the storage medium may reside in an Application Specific Integrated Circuit (ASIC). The ASIC may reside in a wireless modem. In the alternative, the processor and the storage medium may reside as discrete components in the wireless modem.
The previous description of the disclosed examples is provided to enable any person of ordinary skill in the art to make or use the disclosed methods and apparatus. Various modifications to these examples will be readily apparent to those skilled in the art, and the principles defined herein may be applied to other examples without departing from the spirit or scope of the disclosed method and apparatus. The described embodiments are to be considered in all respects only as illustrative and not restrictive and the scope of the invention is, therefore, indicated by the appended claims rather than by the foregoing description. All changes which come within the meaning and range of equivalency of the claims are to be embraced within their scope.

## Claims

1. A disk drive comprising:
a disk configured to spin at a target spin speed and store first data for servicing host commands;
a servo core configured to access the disk and initiate spinning of the disk;
a first non-volatile memory configured to store a first initialization firmware and second data for servicing host commands;
a second non-volatile memory configured to store a second initialization firmware;
a first volatile memory;
a second volatile memory;
a non-volatile memory core configured to access the first non-volatile memory and load the first initialization firmware from the first non-volatile memory to the first volatile memory; and
a main core configured to:
load the second initialization firmware from the second non-volatile memory to the second volatile memory concurrently with the loading of the first initialization firmware from the first non-volatile memory to the first volatile memory by the non-volatile memory core;
control the servo core to initiate spinning of the disk; and
communicate with the non-volatile memory core to service host commands from the first non-volatile memory when the disk is not spinning at the target spin speed.

2. The disk drive of claim 1 wherein the main core is further configured to post a drive ready status to a host after the main core communicates with the non-volatile memory core.

3. The disk drive of claim 2 wherein the main core is further configured to control the servo core to initiate spinning of the disk prior to posting the drive ready status.

4. The disk drive of claim 1 wherein the main core is further configured to post a drive ready status prior to the disk spinning at the target spin speed.

5. The disk drive of claim 1 wherein the main core is further configured to control the servo core to initiate spinning of the disk when a host command from the host requires data stored on the disk.

6. The disk drive of claim 1 wherein the first non-volatile memory comprises a NAND memory.

7. The disk drive of claim 1 wherein the second non-volatile memory comprises a serial flash memory or a NAND memory.

8. The disk drive of claim 1 wherein the second volatile memory comprises a double data rate (DDR) memory.

9. The disk drive of claim 1 wherein the first volatile memory is located in the non-volatile memory core.

10. The disk drive of claim 1 wherein the servo core and the main core are part of a disk controller, and the non-volatile memory core is part of a non-volatile memory controller.

11. The disk drive of claim 10 wherein the disk controller and the non-volatile memory controller are separate from each other.

12. The disk drive of claim 1 wherein the first non-volatile memory and the second non-volatile memory are part of a same memory.

13. A method of operating a disk drive to service host commands from a host, the disk drive comprising a disk configured to spin at a target spin speed and store first data for servicing host commands, a servo core configured to access the disk and initiate spinning of the disk, a first non-volatile memory configured to store a first initialization firmware and second data for servicing host commands, a second non-volatile memory configured to store a second initialization firmware, a first volatile memory, a second volatile memory, a non-volatile memory core, and a main core, the method comprising the steps of:
loading, using the non-volatile memory core, the first initialization firmware from the first non-volatile memory to the first volatile memory;
loading, using the main core, the second initialization firmware from the second non-volatile memory to the second volatile memory concurrently with the loading of the first initialization firmware from the first non-volatile memory to the first volatile memory by the non-volatile memory core;
controlling the servo core to initiate spinning of the disk; and
communicating, using the main core, with the non-volatile memory core to service host commands from the first non-volatile memory when the disk is not spinning at the target spin speed.

14. The method of claim 13 further comprising posting a drive ready status to a host after the main core communicates with the non-volatile memory core.

15. The method of claim 14 further comprising controlling the servo core to initiate spinning of the disk prior to posting the drive ready status.

16. The method of claim 13 further comprising posting the drive ready status prior to the disk spinning at the target spin speed.

17. The method of claim 13 further comprising controlling the servo core to initiate spinning of the disk when a host command from the host requires data stored on the disk.

18. The method of claim 13 wherein the first non-volatile memory comprises a NAND memory.

19. The method of claim 13 wherein the second non-volatile memory comprises a serial flash memory or a NAND memory.

20. The method of claim 13 wherein the second volatile memory comprises a double data rate (DDR) memory.

21. The method of claim 13 wherein the first volatile memory is located in the non-volatile memory core.

22. The method of claim 13 wherein the servo core and the main core are part of a disk controller, and the non-volatile memory core is part of a non-volatile memory controller.

23. The method of claim 22 wherein the disk controller and the non-volatile memory controller are separate from each other.

24. The method of claim 13 wherein the first non-volatile memory and the second non-volatile memory are part of a same memory.