Patent ID: 7900000

Claim:
A computer system comprising: a computer; and a first storage system having one or more first logical storage devices where a plurality of files are stored, wherein said computer comprises: an hash value calculation unit that calculates, when said plurality of files area taken as archive objects, a plurality of hash values that are values intrinsic to contents of a plurality of files, and prohibits said first storage system from updating said one or more first logical storage devices where said plurality of files are stored; and an hash value transmission unit that transmits a plurality of hash values corresponding respectively to said plurality of files to said first storage system, and said first storage system comprises: a duplication determination unit that determines whether two or more identical hash values are contained in said plurality of hash values; and a change control unit that changes an access destination of a first file corresponding to a first hash value from among said two or more hash values to a position having stored therein a second file corresponding to a second hash value from among these two or more hash values when there are said two or more identical hash values.