Data storage system using 3-party hand-off protocol to maintain a single coherent logical image

• US 20030229767A1
• Filed: 06/10/2002
• Published: 12/11/2003
• Est. Priority Date: 06/10/2002
• Status: Active Grant

• Current Assignee: Oracle America, Inc. (Oracle Corporation)
• Original Assignee: Sun Microsystems Incorporated (Oracle Corporation)
• Inventors: Talagala, Nisha, Lee, Whay Sing
• Granted Patent: US 6,857,050 B2
• Time in Patent Office: Days
• US Class Current: 711/154
• CPC Class Codes: G06F 11/2092 Techniques of failing over between control units
• CPC Class Codes: G06F 12/0866 for peripheral storage systems, e.g. disk cache

Abstract

A data storage system is disclosed in which a 3-party hand-off protocol is utilized to maintain a single coherent logical image. In particular, the functionality of the data storage system is separated into distinct processing modules. There are at least three types of processing modules. These three kinds of processing modules function cooperatively to perform data storage operations via the 3-party hand-off protocol. At least two types of processing modules are required to cooperate in a hand-off manner to fully execute each data storage operation.

Claims

1. A data storage system comprising:

(a) one or more first processing modules for interfacing with one or more external systems and for handling cache data in response to one or more received requests from said one or more external systems;

(b) one or more second processing modules for interfacing in a first hand-off manner with said one or more first processing modules and for managing metadata associated with stored data including said cache data to maintain a single coherent logical image of said stored data without performing a locking operation for each received request from said one or more external systems; and

(c) one or more third processing modules for interfacing in a second hand-off manner with said one or more second processing modules and for handling said stored data.

2. A data storage system as recited in claim 1 further comprising:

(d) a disk drive for storing said stored data;

(e) a first memory for storing said cache data; and

(f) a second memory for storing said metadata.

3. A data storage system as recited in claim 2 wherein for a write operation, a particular first processing module writes data received from an external system to a free space in said first memory, and wherein for said write operation, a particular second processing module updates metadata associated with said data received from said external system in said second memory.

4. A data storage system as recited in claim 2 wherein for a read operation, a particular second processing module queries said metadata in said second memory to lookup particular metadata associated with requested data, and wherein for said read operation, a particular first processing module reads requested data from said first memory using said particular metadata.

5. A data storage system as recited in claim 4 wherein said metadata comprises a reference count, wherein for said read operation, said reference count of said requested data is incremented at beginning of said read operation by said particular second processing module, and wherein for said read operation, said reference count of said requested data is decremented at end of said read operation by said particular second processing module.

6. A data storage system as recited in claim 2 wherein for a stage operation, a particular third processing module copies particular data from said disk drive to said first memory based on particular metadata received from a particular second processing module.

7. A data storage system as recited in claim 2 wherein for a destage operation, a particular third processing module copies particular data from said first memory to said disk drive based on particular metadata received from a particular second processing module.

8. A data storage system as recited in claim 1 wherein each first processing module, each second processing module, and each third processing module are implemented in a plurality of distinct central processing units.

9. A data storage system as recited in claim 1 wherein each first processing module and each third processing module are implemented in a plurality of common central processing units.

10. A data storage system comprising:

(a) a disk drive for storing a plurality of data;

(b) a first memory for storing a plurality of cache data;

(c) a second memory for storing metadata associated with stored data including said cache data and said data;

(d) one or more first processing modules for interfacing with one or more external systems and for moving said cache data between said one or more external systems and said first memory;

(e) one or more second processing modules for interfacing in a first hand-off manner with said one or more first processing modules and for managing said metadata to maintain a single coherent logical image of said stored data without performing a locking operation for each received request from said one or more external systems; and

(f) one or more third processing modules for interfacing in a second hand-off manner with said one or more second processing modules and for moving said stored data between said first memory and said disk drive.

11. A data storage system as recited in claim 10 wherein for a write operation, a particular first processing module writes data received from an external system to a free space in said first memory, and wherein for said write operation, a particular second processing module updates metadata associated with said data received from said external system in said second memory.

12. A data storage system as recited in claim 10 wherein for a read operation, a particular second processing module queries in said second memory said metadata to lookup particular metadata associated with requested data, and wherein for said read operation, a particular first processing module reads requested data from said first memory using said particular metadata.

13. A data storage system as recited in claim 12 wherein said metadata comprises a reference count, wherein for said read operation, said reference count of said requested data is incremented at beginning of said read operation by said particular second processing module, and wherein for said read operation, said reference count of said requested data is decremented at end of said read operation by said particular second processing module.

14. A data storage system as recited in claim 10 wherein for a stage operation, a particular third processing module copies particular data from said disk drive to said first memory based on particular metadata received from a particular second processing module.

15. A data storage system as recited in claim 10 wherein for a destage operation, a particular third processing module copies particular data from said first memory to said disk drive based on particular metadata received from a particular second processing module.

16. A data storage system as recited in claim 10 wherein each first processing module, each second processing module, and each third processing module are implemented in a plurality of distinct central processing units.

17. A data storage system as recited in claim 10 wherein each first processing module and each third processing module are implemented in a plurality of common central processing units.

18. A method of responding to a plurality of requests from one or more external systems received by a data storage system, comprising:

a) receiving each request at a first type processing module of said data storage system for interfacing with said one or more external systems and for handling cache data; and

b) for each received request, responding by performing a hand-off protocol comprising;

1) if required by said received request, interfacing to execute a first corresponding data storage operation in a first hand-off manner between said first type processing module and a second type processing module of said data storage system for managing metadata associated with stored data including said cache data to maintain a single coherent logical image of said stored data; and

2) if required by said received request, interfacing to execute a second corresponding data storage operation in a second hand-off manner between said second type processing module and a third type processing module of said data storage system for handling said stored data.

19. A method as recited in claim 18 wherein said first type processing module, said second type processing module, and said third type processing module are each implemented in a plurality of distinct central processing units.

20. A method as recited in claim 18 wherein said first type processing module and said third type processing module are implemented in a common central processing unit.

21. A method as recited in claim 18 wherein said first corresponding data storage operation is one of a read operation and a write operation.

22. A method as recited in claim 18 wherein said second corresponding data storage operation is one of a stage operation and a destage operation.