Methods and systems for performing a read ahead operation using an intelligent storage adapter

1. A machine implemented method, comprising:

maintaining a data structure by an adapter to track whether data blocks associated with a logical unit number (LUN) have been written or modified;

extracting a starting logical block address (LBA) for executing a read request for reading data stored using the LUN;

generating a LBA range for a read ahead operation that is used to predict data that may be read subsequent to the read request;

determining if blocks associated with the LBA range for the read ahead operation have been written or modified;

only reading ahead the blocks associated with the LBA range, when the blocks have been written to or modified; and

temporarily storing read ahead data at a cache LUN maintained by the adapter.

2. The method of claim 1 , wherein the LUN is based on storage space at a storage device that is accessible via a storage area network (SAN).

3. The method of claim 1 , wherein the cache LUN is based on storage space at a local solid state storage device that is managed by the adapter.

4. The method of claim 1 , wherein the adapter maintains a bitmap for tracking blocks associated with the LBA range that may have been written or modified.

5. The method of claim 1 , wherein the blocks associated with the LBA range are not read if the blocks have not been written to or modified.

6. The method of claim 1 , wherein LBA range for the read ahead operation is greater than an LBA range of the read request.

7. The method of claim 1 , wherein the entire LBA range is read ahead if any block within the LBA range has been written to or modified.

8. A non-transitory, machine readable storage medium storing executable instructions, which when executed by a machine, causes the machine to perform a method, the method comprising:

maintaining a data structure by an adapter to track whether data blocks associated with a logical unit number (LUN) have been written or modified;

extracting a starting logical block address (LBA) for executing a read request for reading data stored using the LUN;

generating a LBA range for a read ahead operation that is used to predict data that may be read subsequent to the read request;

determining if blocks associated with the LBA range for the read ahead operation have been written or modified;

only reading ahead the blocks associated with the LBA range, when the blocks have been written to or modified; and

temporarily storing read ahead data at a cache LUN maintained by the adapter.

9. The storage medium of claim 8 , wherein the LUN is based on storage space at a storage device that is accessible via a storage area network (SAN).

10. The storage medium of claim 8 , wherein the cache LUN is based on storage space at a local solid state storage device that is managed by the adapter.

11. The storage medium of claim 8 , wherein the adapter maintains a bitmap for tracking blocks associated with the LBA range that may have been written or modified.

12. The storage medium of claim 8 , wherein the blocks associated with the LBA range are not read if the blocks have not been written to or modified.

13. The storage medium of claim 8 , wherein LBA range for the read ahead operation is greater than an LBA range of the read request.

14. The storage medium of claim 8 , wherein the entire LBA range is read ahead if any block within the LBA range has been written to or modified.

15. A system comprising:

a processor executing instructions out of a memory for:

maintaining a data structure by an adapter to track whether data blocks associated with a logical unit number (LUN) have been written or modified;

extracting a starting logical block address (LBA) for executing a read request for reading data stored using the LUN;

generating a LBA range for a read ahead operation that is used to predict data that may be read subsequent to the read request;

determining if blocks associated with the LBA range for the read ahead operation have been written or modified;

only reading ahead the blocks associated with the LBA range, when the blocks have been written to or modified; and

temporarily storing read ahead data at a cache LUN maintained by the adapter.

16. The system of claim 14 , wherein the LUN is based on storage space at a storage device that is accessible via a storage area network (SAN).

17. The system of claim 14 , wherein the cache LUN is based on storage space at a local solid state storage device that is managed by the adapter.

18. The system of claim 14 , wherein the adapter maintains a bitmap for tracking blocks associated with the LBA range that may have been written or modified.

19. The system of claim 14 , wherein the blocks associated with the LBA range are not read if the blocks have not been written to or modified.

20. The system of claim 14 , wherein LBA range for the read ahead operation is greater than an LBA range of the read request.

21. The system of claim 14 , wherein the entire LBA range is read ahead if any block within the LBA range has been written to or modified.