Disc storage system having a non-volatile cache to store write data in the event of a power failure

• US 6,295,577 B1
• Filed: 02/23/1999
• Issued: 09/25/2001
• Est. Priority Date: 02/24/1998
• Status: Expired due to Term

• Current Assignee: Seagate Technology LLC (Seagate Technology Holdings Plc)
• Original Assignee: Seagate Technology LLC (Seagate Technology Holdings Plc)
• Inventors: Norman, Robert W. Jr., Gaertner, Mark A., Anderson, David B., Forehand, Monty A.
• Primary Examiner(s): NGUYEN, THAN VINH
• Application Number:
  US09/255,473
• Time in Patent Office: 945 Days
• Field of Search: 711/111-114, 711/118, 711/119, 360/69-75, 714/2, 714/14, 714/15, 714/18, 714/22, 714/24
• US Class Current: 711/113
• CPC Class Codes: G06F 11/1441 Resetting or repowering
• CPC Class Codes: G06F 11/1666 where the redundant component is memory or memory area
• CPC Class Codes: G06F 11/20 using active fault-masking, e.g. by switching out faulty elements or by switching in spare elements
• CPC Class Codes: G06F 12/0804 with main memory updating G06F12/0806 takes precedence
• CPC Class Codes: G06F 12/0866 for peripheral storage systems, e.g. disk cache
• CPC Class Codes: G06F 2212/312 In storage controller
• CPC Class Codes: G11B 19/04 Arrangements for preventing, inhibiting, or warning against double recording on the same blank or against other recording or reproducing malfunctions

Abstract

A disc storage system having a host computer interface adapted to coupled to a host computer, a disc storage medium having a disc surface and a spindle motor coupled to the disc adapted to rotate the disc. A transducer is positioned for reading and writing data on the disc surface. The system further includes a volatile memory write cache and a non-volatile memory write cache adapted to store data during a power loss. A method is also provided for storing data prior to writing the data in a non-volatile memory cache in a disc storage system.

Claims

1. A disc storage system, comprising:

(a) a rotatable storage disc having a disc surface;

(b) a spindle motor operably coupled to the disc which is adapted to rotate the disc;

(c) a transducer adapted for reading and writing data on the disc surface;

(d) a volatile memory cache adapted to store data prior to writing the data to the disc surface;

(e) a non-volatile memory cache in the disc storage system adapted to store data during a power loss; and

(f) a controller in the storage system adapted to receive data from a host computer interface, temporarily cache the data in the volatile memory cache, and subsequently write the data onto the disc surface with the transducer, the controller further adapted to store the data in the non-volatile memory only upon detection of a power loss to the storage system.

2. The disc storage system of claim 1 wherein the spindle motor generates a back EMF (ElectroMotive Force) signal upon loss of power, the back EMF signal is operatively coupled to the controller and the non-volatile memory to power the controller and the non-volatile memory upon loss of power supplied to the storage system.

3. The disc storage system of claim 2 including a voltage regulator which operatively couples the back EMF signal to the controller.

4. The disc storage system of claim 1 wherein the controller reads data from the non-volatile memory upon power up of the storage system.

5. The disc storage system of claim 4 wherein the controller writes the information read from the non-volatile memory to the disc surface.

6. The disc storage system of claim 1 wherein the controller receives a power condition signal from the spindle motor indicative of a loss of power to the storage system.

7. A method of caching data to be written to a disc storage system, comprising steps of:

(a) receiving the data from a host computer;

(b) storing the data in a volatile memory cache;

(c) retrieving the data from the volatile memory cache and writing the data to the disc storage medium;

(d) detecting a power loss to the disc storage system; and

(e) writing data to a non-volatile memory cache only upon detection of a power loss.

8. The method of claim 7 including a step (f) of obtaining power for the writing step (e) from a back EMF (ElectroMotive Force) signal generated by a spindle motor of the disc storage system.

9. The method of claim 7 including steps of:

(f) reading data from the non-volatile memory cache upon power up of the disc storage system; and

(g) writing data read from the non-volatile memory cache to the disc storage medium.

10. A disc storage system which implements the method of claim 7.

11. A disc storage system, comprising:

a transducer adapted to read and write data on a disc storage medium; and

means for caching data in operable relation to writing the data on the disc storage medium and upon detection of a power loss.

12. A disc storage system, comprising:

(a) a rotatable storage disc having a disc surface;

(b) a spindle motor operably coupled to the disc which is adapted to rotate the disc;

(c) a transducer adapted for reading and writing data on the disc surface;

(d) a volatile memory cache adapted to store data prior to writing the data to the disc surface;

(e) a non-volatile memory cache in the disc storage system adapted to store data during a power loss;

(f) a controller in the storage system adapted to receive data from a host computer interface, temporarily cache the data in the volatile memory cache, and subsequently write the data onto the disc surface with the transducer, the controller further adapted to store the data in the non-volatile memory upon detection of a power loss to the storage system; and

(g) wherein the spindle motor generates a back EMF (ElectroMotive Force) signal upon loss of power, the back EMF signal is operatively coupled to the controller and the non-volatile memory to power the controller and the non-volatile memory upon loss of power supplied to the storage system.

13. A method of caching data to be written to a disc storage system, comprising steps of:

(a) receiving the data from a host computer;

(b) storing the data in a volatile memory cache;

(c) retrieving the data from the volatile memory cache and writing the data to the disc storage medium;

(d) detecting a power loss to the disc storage system;

(e) writing data to a non-volatile memory cache upon detection of a power loss; and

(f) obtaining power for the writing step (e) from a back EMF (ElectroMotive Force) signal generated by a spindle motor of the disc storage system.