Fast path for performing data operations

• US 7,280,536 B2
• Filed: 09/15/2006
• Issued: 10/09/2007
• Est. Priority Date: 12/10/2001
• Status: Expired due to Fees

• Current Assignee: International Business Machines Corporation
• Original Assignee: Incipient Inc.
• Inventors: Testardi, Richard
• Primary Examiner(s): Ellis; Kevin L.
• Assistant Examiner(s): Chery; Mardochee
• Application Number:
  US11/522,260
• Publication Number:
  US 20070016754A1
• Time in Patent Office: 389 Days
• Field of Search: None
• US Class Current: 370/355
• CPC Class Codes: G06F 3/0611 in relation to response time
• CPC Class Codes: G06F 3/0635 by changing the path, e.g. traffic rerouting, path reconfiguration
• CPC Class Codes: G06F 3/067 Distributed or networked storage systems, e.g. storage area networks [SAN], network attached storage [NAS]
• CPC Class Codes: H04L 67/1097 for distributed storage of data in networks, e.g. transport arrangements for network file system [NFS], storage area networks [SAN] or network attached storage [NAS]

Abstract

Described are techniques used in a computer system for handling data operations to storage devices. A switching fabric includes one or more fast paths for handling lightweight, common data operations and at least one control path for handling other data operations. A control path manages one or more fast paths. The fast path and the control path are utilized in mapping virtual to physical addresses using mapping tables. The mapping tables include an extent table of one or more entries corresponding to varying address ranges. The size of an extent may be changed dynamically in accordance with a corresponding state change of physical storage. The fast path may cache only portions of the extent table as needed in accordance with a caching technique. The fast path may cache a subset of the extent table stored within the control path. A set of primitives may be used in performing data operations. A locking mechanism is described for controlling access to data shared by the control paths.

Claims

1. A method executed in a computer system for processing a data operation comprising:

determining if said data operation has at least one predetermined criteria characterizing said data operation as being a commonly performed non-complex data operation using a primitive operation; and

routing said data operation to a fast path for processing if said data operation has said at least one predetermined criteria, and routing said data operation to a general control path for processing otherwise.

2. The method of claim 1, wherein said predetermined criteria is one of:

said data operation is within a single logical volume, said data operation involves data from within virtual address boundaries of a single mapping table entry, said data operation is a read operation, and said data operation is a write operation.

3. The method of claim 1, wherein said predetermined criteria is one of:

said data operation is indicated as allowable in accordance with information included in a mapping table used in mapping virtual to physical locations for said data operation, and said data operation does not cause a serialization conflict in connection with a mirrored device.

4. The method of claim 1, further comprising:

routing said data operation to said general control path by causing a fault if said data operation does not have said at least one predetermined criteria.

5. The method of claim 1, further comprising:

routing said data operation to said general control path in accordance with information included in a mapping table associated with a virtual address to physical address translation of an address of said data operation.

6. The method of claim 5, further comprising:

determining a volume segment descriptor associated with said data operation, said volume segment descriptor including said mapping table.

7. The method of claim 1, wherein said data operation is issued by said fast path if said data operation has said at least one predetermined criteria and is otherwise issued by said general control path.

8. The method of claim 1, wherein said data operation is an upstream data operation from a host and the method further comprising:

producing at least one downstream data operation to a physical device associated with said data operation corresponding to said upstream data operation; and

creating an element on a pending data operation list corresponding to said data operation.

9. The method of claim 1, further comprising:

routing return data operation data using said fast path to a host that issued said data operation if there is no error, and otherwise routing return data operation data using said general control path to a host that issued said data operation.

10. A computer program product tangibly embodied a computer-readable medium, for processing a data operation, the computer program product including instructions being operable to cause data processing apparatus to:

determine if said data operation has at least one predetermined criteria characterizing said data operation as being a commonly performed non-complex data operation using a primitive operation; and

route said data operation to a fast path for processing if said data operation has said at least one predetermined criteria, and routing said data operation to a general control path for processing otherwise.

11. The computer program product of claim 10, wherein said predetermined criteria is one of:

said data operation is within a single logical volume, said data operation involves data from within virtual address boundaries of a single mapping table entry, said data operation is a read operation, and said data operation is a write operation.

12. The computer program product of claim 10, wherein said predetermined criteria is one of:

said data operation is indicated as allowable in accordance with information included in a mapping table used in mapping virtual to physical locations for said data operation, and said data operation does not cause a serialization conflict in connection with a mirrored device.

13. The computer program product of claim 12, further operable to cause the data processing apparatus to:

determine a volume segment descriptor associated with said data operation, said volume segment descriptor including said mapping table.

14. The computer program product of claim 10, further operable to cause the data processing apparatus to:

route said data operation to said general control path by causing a fault if said data operation does not have said at least one predetermined criteria.

15. The computer program product of claim 10, further operable to cause the data processing apparatus to:

route said data operation to said general control path in accordance with information included in a mapping table associated with a virtual address to physical address translation of an address of said data operation.

16. The computer program product of claim 10, wherein said data operation is issued by said fast path if said data operation has said at least one predetermined criteria and is otherwise issued by said general control path.

17. The computer program product of claim 10, wherein said data operation is an upstream data operation from a host and the computer program product further operable to cause the data processing apparatus to:

produce at least one downstream data operation to a physical device associated with said data operation corresponding to said upstream data operation; and

create an element on a pending data operation list corresponding to said data operation.

18. The computer program product of claim 10, further operable to cause the data processing apparatus to:

route return data operation data using said fast path to a host that issued said data operation if there is no error, and otherwise route return data operation data using said general control path to a host that issued said data operation.