Patent ID: 8468138

Claim:
A method of file deduplication implemented in a computer infrastructure comprising a combination of hardware and software, the method comprising: receiving a request to save a first file as immutable; searching for a second file that is saved and is redundant to the first file; determining the second file is one of mutable and immutable; when the second file is mutable, saving the first file as a master copy, and replacing the second file with a soft link pointing to the master copy; and when the second file is immutable, determining which of the first and second files has a later expiration date and an earlier expiration date, saving the one of the first and second files with the later expiration date as a master copy, and replacing the one of the first and second files with the earlier expiration date with a soft link pointing to the master copy, wherein the soft link contains data defining the earlier expiration date, the second file has the earlier expiration date, and the replacing comprises deleting a saved copy of the second file.