Patent ID: 8176008

Claim:
A storage system comprising: a first storage system storing first data, wherein the first storage system is operable to replicate the first data to produce a first snapshot data; a second storage system storing second data, wherein the second storage system is operable to replicate the second data to produce a second snapshot data; and a management computer; wherein the management computer sends a request to take a snapshot to the first storage system, wherein the first storage system produces the first snapshot data by replicating the first data according to the request to take the snapshot, wherein the second storage system produces the second snapshot data by replicating the second data; wherein if the first data includes a first referral information pointing to the second data, a second referral information of the first snapshot data is changed from pointing to the second data to pointing to the second snapshot data; wherein the first storage system sends a second request to take a snapshot to the second storage system if the first data includes the first referral information pointing to the second data; wherein the second storage system produces the second snapshot data by replicating the second data according to the second request to take the snapshot; wherein the first storage system checks, from searching referral information within data exported by the first storage system, whether the first data includes the first referral information pointing to the second data or not; wherein the second referral information of the first snapshot data is changed from pointing to the second data to pointing to the second snapshot data if the first referral information pointing to the second data was found in the data exported by the first storage system.