File change detection

1. A computer implemented method comprising:

selecting a file for potential backing up via the computer;

calculating a metadata signature hash via the computer on data consisting of metadata which corresponds to the selected file;

identifying an already backed up file corresponding to the selected file using an identifier which accompanies the metadata signature;

comparing the metadata signature of the selected file to a metadata signature of the identified corresponding file already backed up via the computer; and

only backing up the file to a computer readable storage device if the signatures do not match.

2. The method of claim 1 wherein the hash is calculated in accordance with an MD5 hash algorithm.

3. The method of claim 1 wherein the metadata includes a file path and size.

4. The method of claim 3 wherein the metadata further includes file attributes and security access control lists.

5. The method of claim 4 wherein the metadata further includes dates of last modification and creation of the file.

6. The method of claim 1 wherein the method is repeated for each file in a data storage system.

7. A computer implemented method comprising:

selecting a file for potential backing up;

obtaining metadata for the file via the computer, the metadata consisting of a file path and size, file attributes, file security access control lists, dates of last modification or creation of the file;

calculating a metadata signature hash on the obtained metadata via the computer;

identifying an already backed up file corresponding to the selected file using an identifier which accompanies the metadata signature;

comparing the metadata signature of the selected file to a metadata signature of the identified corresponding file already backed up via the computer; and

only backing up the file to a computer readable storage device if the signatures do not match.

8. A computer readable storage device having instructions for causing a computer to execute a method, the method comprising:

selecting a file for potential backing up;

calculating a metadata signature hash on data consisting of metadata which corresponds to the selected file;

identifying an already backed up file corresponding to the selected file using an identifier which accompanies the metadata signature;

comparing the metadata signature of the selected file to a metadata signature of the identified corresponding file already backed up; and

only backing up the file if the signatures do not match.

9. The computer readable storage device of claim 8 wherein the hash is calculated in accordance with an MD5 hash algorithm.

10. The computer readable storage device of claim 8 wherein the metadata includes a file path and size.

11. The computer readable storage device of claim 10 wherein the metadata further includes file attributes and security access control lists.

12. The computer readable storage device of claim 11 wherein the metadata further includes dates of last modification and creation of the file.

13. The computer readable storage device of claim 8 wherein the method is repeated for each file in a data storage system.

14. A system comprising:

a backup agent computer system adapted to couple to a data storage system and receive file data and metadata and calculate a signature hash for each file as a function of variables consisting of metadata; and

a backup server computer system coupled to receive the metadata signature from the backup agent, identify an already backed up file corresponding to the selected file using an identifier which accompanies the metadata signature, and compare the metadata signature for the selected file to a metadata signature of the already backed up identified corresponding file, and if the signature do not match, backing up the file corresponding to the metadata signature created by the backup agent.

15. The system of claim 14 wherein the hash is calculated in accordance with an MD5 hash algorithm.

16. The system of claim 14 wherein the metadata includes a file path and size.

17. The system of claim 16 wherein the metadata further includes file attributes and security access control lists.

18. The system of claim 17 wherein the metadata further includes dates of last modification and creation of the file.

19. The system of claim 14 wherein the method is repeated for each file in a data storage system.