Patent ID: 8463871

Claim:
A method for data backup, the method comprising: assigning identifiers to a client data item at a client; generating a hash of the client data item at a client; transmitting the hash to a server; comparing the hash against hashes for data items belonging to multiple clients stored in a hash table at the server; if an identical hash is found: transmitting a server data item corresponding to the hash and to the identifiers to the client; on the client, comparing the server data item with the client data item, and if the client data item and the server data item are identical, transmitting the identifiers to the server and storing the identifiers in a configurations repository; and if the client data item and the server data item are different, transmitting the client data item to the server and storing the client data item in the data repository, the data item being assigned a unique identifier in a common namespace across multiple physical servers, for translation of a file pathname; transmitting the identifiers to the server and storing the identifiers in the configurations repository; and if the identical hash is not found, transmitting the client data item to the server and storing the client data item in the data repository; and transmitting the identifiers to the server and storing the identifiers in the configurations repository.