Method for transferring data from a host computer to a storage media using selectable caching strategies

• US 6,412,045 B1
• Filed: 05/23/1995
• Issued: 06/25/2002
• Est. Priority Date: 05/23/1995
• Status: Expired due to Term

• Current Assignee: Avago Technologies International Sales Pte Limited (Broadcom, Inc.)
• Original Assignee: LSI Logic Corporation (Broadcom, Inc.)
• Inventors: Johnson, Max L., Rink, Curtis W., DeKoning, Rodney A., Humlicek, Donald R.
• Primary Examiner(s): KIM, HONG CHONG
• Application Number:
  US08/447,594
• Time in Patent Office: 2,590 Days
• Field of Search: 395/462, 395/465, 395/440, 395/444, 711/135, 711/133, 711/134, 711/113, 711/118, 711/138, 711/143
• US Class Current: 711/135
• 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

Abstract

An apparatus and method is disclosed which enables a host computer to adjust the caching strategy used for writing its write request data to storage media during execution of various software applications. The method includes the step of generating a caching-flushing parameter in the host computer. The cache flushing parameter is then transferred from the host computer to a controller which has a cache memory. Thereafter, a quantity of write request data is written from the cache memory to a storage medium in accordance with the cache-flushing parameter.

Claims

1. A method for transferring data to a storage medium, comprising the steps of:

providing a controller having a cache memory;

generating a cache-flushing parameter in a host computer;

transferring the cache-flushing parameter from the host computer to the controller;

writing a quantity of write request data from the cache memory of the controller to the storage medium in accordance with the cache-flushing parameter,

initiating the writing step when an amount of unwritten write request data stored in the cache memory exceeds a first predetermined threshold value derived from the cache-flushing Parameter; and

terminating the writing step when the amount of unwritten write request data drops below a second predetermined threshold value derived from another cache-flushing parameter.

2. The method of claim 1, wherein the writing step includes the step of:

writing the write request data to the storage media after elapse of a time interval derived from the cache-flushing parameter.

3. The method of claim 1, wherein the writing step includes the steps of:

determining a time interval value from the cache-flushing parameter; and

writing the write request data to the storage media after elapse of the time interval.

4. The method of claim 1, further comprising the steps of:

generating a second cache-flushing parameter in the host computer;

transferring the second cache-flushing parameter from the host computer to the controller;

detecting a low battery condition; and

writing a second quantity of write request data from the cache memory of the controller to the storage medium in accordance with the second cache-flushing parameter in response to the detecting step.

5. The method of claim 4, wherein:

said controller includes a memory buffer,

said first cache-flushing parameter is stored in said memory buffer at a first location, and

said second cache-flushing parameter is stored in said memory buffer at a second location which is different from said first location.

6. The method of claim 5, wherein said first cache-flushing parameter and said second cache-flushing parameter are simultaneously stored in said memory buffer.

7. A method of transferring data from a host computer to a storage media, comprising the steps of:

sending a first caching parameter which defines a first caching strategy to a controller;

transferring a first quantity of data from the host computer to the storage media based on the first caching parameter;

sending a second caching parameter which defines a second caching strategy to the controller;

transferring a second quantity of data from the host computer to the storage media based on the second caching parameter;

initiating the first quantity transferring step when an amount of unwritten write request data stored in the cache memory exceeds a first predetermined threshold value derived from the first cache-flushing parameter; and

terninating the first quantity transferring step when the amount of unwritten write request data drops below a second predetermined threshold value derived from another cache flushing parameter associated with the cache memory.

8. The method of claim 7, wherein:

the first caching parameter sending step includes the step of storing the first caching parameter in a buffer in the controller; and

the second caching parameter sending step includes the step of overwriting the first caching parameter with the second caching parameter in the buffer.

9. A method for transferring data to a storage device, comprising the steps of:

updating a cache-flushing parameter associated with a cache memory;

flushing the cache memory to the storage device in accordance with the cache flushing parameter after the updating step;

initiating the flushing step when an amount of unwritten write request data stored in the cache memory exceeds a first predetermined threshold value derived from the cache-flushing parameter; and

terminating the flushing step when the amount of unwritten write request data drops below a second predetermined threshold value derived from another cache flushing parameter associated with the cache memory.

10. The method of claim 9, wherein the flushing step includes the step of:

flushing the cache memory at a time interval derived from the cache-flushing parameter.

11. The method of claim 9, wherein the flushing step includes the steps of:

determining a time interval value from the cache-flushing parameter; and

flushing the cache memory in accordance with the time interval value.

12. The method of claim 9, wherein the updating step includes the steps of:

generating the cache-flushing parameter in a host computer; and

sending the cache-flushing parameter to a controller.

13. The method of claim 12, wherein the updating step further includes the step of:

storing the cache-flushing parameter in a buffer of the controller.

14. A method for controlling cache flushing characteristics of a storage device, with the storage device having a controller which includes a cache memory, comprising the steps of:

sending a cache-flushing parameter to the controller;

flusning the cache memory of the controller in accordance with the cache-flushing parameters

initiating the flushing step when an amount of unwritten write request data stored in the cache memory exceeds a first predetermined threshold value derived from the cache-flushing parameter; and

terminating the flushing step when the amount of unwritten write request data drops below a second predetermined threshold value derived from another cache-flushing parameter.

15. The method of claim 14, wherein the flushing step includes the step of:

flushing the cache memory at a time interval derived from the cache-flushing parameter.

16. The method of claim 14, wherein the flushing step includes the steps of:

determining a time interval value from the cache-flushing parameter; and

flushing the cache memory in accordance with the time interval value.

17. The method of claim 14, further comprising the steps of:

generating the cache-flushing parameter in a host device before the sending step; and

storing the cache-flushing parameter in a buffer of the controller after the sending step.

18. A program storage device readable by a machine, tangibly embodying a program or instructions executable by the machine to perform method steps for transferring data to a storage medium, said method steps comprising:

providing a controller having a cache memory;

generating a cache-flushing parameter in a host computer;

transferring the cache-flushing parameter from the host computer to the controller;

writing a quantity of write request data from the cache memory of the controller to the storage medium in accordance with the cache-flushing parameter;

initiating the writing step when an amount of unwritten write request data stored in the cache memory exceeds a first predetermined threshold value derived from the cache-flushing parameter; and

terminating the writing step when the amount of unwritten write request data drops below a second predetermined threshold value derived from another cache-flushing parameter.