Patent ID: 8234473

Claim:
A storage system coupled to a host computer via a network comprising: a data volume storing write data from the host computer; a snapshot storing area storing a plurality of snapshots; a journal storing area storing journal entries associated with the write data, the journal entries including a journal entry between a first point in time and a second point in time; and a storage controller to conduct write operations according to write requests received from the host computer, to manage snapshot operations to store the plurality of snapshots, and to perform data recovery with a target time using at least one of the journal entries and a selected snapshot among the plurality of snapshots, wherein the journal entries are generated for each of the write operations issued from the host computer and each of the journal entries includes a unique sequence number assigned by the storage system when a corresponding one of the journal entries is generated, wherein the storage system manages journal operations to record the journal entries, and to apply the at least one of the journal entries to the selected snapshot, wherein the storage system maintains a management table storing relationship information for each of the journal entries in association with the snapshots, wherein the storage controller selects a snapshot that is closest in time to the target time from among the plurality of snapshots as the selected snapshot, and applies the at least one journal entry to the selected snapshot in sequential order to perform the data recovery by referring to the management table, and wherein said unique sequence numbers are used to select the at least one journal entry to be sequentially applied to said selected snapshot.