Mass storage accelerator

• US 7,310,699 B2
• Filed: 09/29/2006
• Issued: 12/18/2007
• Est. Priority Date: 02/04/2004
• Status: Active Grant

• Current Assignee: SanDisk Technologies LLC (Western Digital Corporation)
• Original Assignee: SanDisk Corporation (Western Digital Corporation)
• Inventors: Sinclair, Alan Welsh
• Primary Examiner(s): Elmore, Stephen C.
• Application Number:
  US11/541,013
• Publication Number:
  US 20070028040A1
• Time in Patent Office: 445 Days
• Field of Search: 711/100, 711/103, 711/111, 711/154, 711/221
• US Class Current: 711/100
• CPC Class Codes: G06F 3/0613 in relation to throughput
• CPC Class Codes: G06F 3/0656 Data buffering arrangements
• CPC Class Codes: G06F 3/0685 Hybrid storage combining heterogeneous device types, e.g. hierarchical storage, hybrid arrays

Abstract

A data storage device is provided. A disk device is combined with a non-volatile memory device to provide much shorter write access time and much higher data write speed than can be achieved with a disk device alone. Interleaving bursts of sector writes between the two storage devices can effectively eliminate the effect of the seek time of the disk device. Following a non-contiguous logical address transition from a host system, the storage controller can perform a look-ahead seek operation on the disk device, while writing current data to the non-volatile memory device. Such a system can exploit the inherently faster write access characteristics of a non-volatile memory device, eliminating the dead time normally caused by the disk seek time.

Claims

1. A method of improving the performance of reading data from a rotating disk drive, comprising:

receiving a first command from a host system to read a burst of data with a defined starting address in the rotating disk drive;

determining if the address for the burst of data for the first command is non-contiguous to a previously accessed address;

if it has been determined that the address is non-contiguous, then

reading the requested data from the rotating disk drive and copying an initial portion of the data to a non-volatile memory device;

subsequently receiving a second command from the host system to read a burst of data with the same starting address in the rotating disk drive;

determining if the address for the burst of data from the second command is non- contiguous to a previously accessed address;

if it has been determined that the address is non-contiguous, then

reading the initial portion of the requested data from the non-volatile memory device, and reading the remainder of the requested data from the rotating disk drive, thereby eliminating delay in providing data to the host system caused by seek time in the rotating disk drive.

2. The method of claim 1, wherein the rotating disk drive and the non-volatile device are part of a computer system, and wherein the non-volatile memory device is removable from the computer system.

3. The method of claim 1, wherein the non-volatile memory device is a solid-state memory.

4. The method of claim 3, wherein the solid-state memory is flash memory, and wherein the rotating disk drive is a magnetic hard disk drive.

5. A method of improving the performance of reading data from a hard drive provided in a computer system, comprising:

receiving a request from a host system to read data with a defined starting address in the hard drive;

determining if the address of requested data is contiguous to a previously accessed data;

if the address of the requested data is contiguous to the previously accessed data, then reading the requested data from the hard drive; and

if the address of the requested data is not contiguous to the previously accessed data, then determining whether a first portion of the requested data resides on a non-volatile mass storage device;

if the first portion of the requested data resides on the non-volatile mass storage device, then reading the first portion of the requested data from the non-volatile mass storage device and reading the remainder of the requested data from the hard drive; and

if the first portion of the requested data does not reside on the non-volatile mass storage device, then reading the requested data from the hard drive and copying the first portion of the requested data to the non-volatile mass storage device.

6. A data storage system comprising:

a first non-volatile storage device;

a second non-volatile storage device having a slower average access time and a higher capacity than the first storage device, wherein the slower average access time is the average delay that is necessary before the second non-volatile storage device can begin to read data; and

a storage controller operable to retrieve a first portion of data from the first storage device and a second portion of data from the second storage device, to receive a first command from a host system to read a data fragment with a defined starting address in the second storage device;

to determine if the address for the data fragment for the first command is non-contiguous to a previously accessed address; and

if it has been determined that the address is non-contiguous, then to read the requested data from the second storage device and to copy an initial portion of the data to the first storage device.

7. The data storage system of claim 6, wherein the storage controller is further operable to:

subsequently receive a second command from the host system to read a data fragment with the same starting address in the second storage device;

determine if the address for the data fragment from the second command is non-contiguous to a previously accessed address;

if it has been determined that the address is non-contiguous, then read the initial portion of the requested data from the first storage device, and to read the remainder of the requested data from the second storage device.

8. The data storage system of claim 7,

wherein the first storage device is solid-state memory, and the second storage device is a hard drive, and

wherein, if it has been determined that the address is non-contiguous, then the reading of the initial portion of the requested data from the first storage device serves to reduce delay in providing data to the host system that would otherwise be caused by a seek delay of the hard drive in transitioning to the address that is non-contiguous.

9. A method for storing data comprising:

receiving a write command from a host system bus to write to a data address;

receiving a data fragment from the host system bus;

storing a first portion of the data fragment in a first storage device;

causing, prior to the completion of storing the first portion of the data fragment in the first storage device, a second storage device to be prepared to write data; and

storing a remaining portion of the data fragment in the second storage device after the second storage device has been prepared;

updating a head table that contains information relating to the location of the first portion of data and the remaining portion of data; and

subsequently copying the first portion of the data fragment from the first storage device to the data address in the second storage device.

10. The method for storing data of claim 9, further comprising updating a head table that contains information relating to the location of the first portion of data and the remaining portion of data.

11. The method for storing data of claim 9, wherein the copying is performed during when the host system bus is not requesting access to the data contained in either the first or second storage device.

12. The method for storing data of claim 9, wherein the entire data fragment is stored exclusively in the second storage device if the first storage device is not available.

13. A method for retrieving data comprising:

receiving a read command from a host system bus to read data at a data address;

determining if a first portion of the data resides on a first storage device;

if the first portion of data resides on the first storage device, then reading the first portion of the data from the first storage device;

causing, prior to the completion of reading the first portion of the data fragment in the first storage device, a second storage device to be prepared to read a remaining portion of the data; and

reading the remaining portion of data from the second storage device after the second storage device has been prepared to read the remaining portion of the data; and

if the first portion of data does not reside on the first storage device, then reading both the first portion of the data and the remaining portion of the data from the second storage device.

14. The method for retrieving data of claim 13, wherein both the first portion of data and the remaining portion of data are read from the second storage device if the first storage device is not available.

15. A computer-readable medium including at least computer program code for retrieving data, the computer-readable medium comprising:

computer program code for receiving a read command from a host system bus to read data at a data address;

computer program code for determining if a first portion of the data resides on a first storage device;

computer program code for, if the first portion of data resides on the first storage device, then

reading the first portion of the data from the first storage device;

causing, prior to the completion of reading the first portion of the data fragment in

the first storage device, a second storage device to be prepared to read a remaining portion of the data; and

reading the remaining portion of data from the second storage device after the second storage device has been prepared to read the remaining portion of the data; and

computer program code for, if the first portion of data does not reside on the first storage device, then reading both the first portion of the data and the remaining portion of the data from the second storage device.