Patent ID: 8244685

Claim:
A method of restoring a set of files from a collection of blocks, the set of files having existed at a particular time within a predefined time window, the method comprising: storing the collection of blocks within a storage subsystem that includes (i) a premium storage area and (ii) a low-end storage area, wherein the premium storage area has a performance metric that is better than a performance metric of the low-end storage area, the collection of blocks defining the set of files at multiple different times within the predefined time window, the collection of blocks including (i) a first baseline of blocks which defines the set of files at a first baseline time within the predefined time window, (ii) older blocks which were formed before the first baseline time within the predefined time window, and (iii) newer blocks which were formed after the first baseline time within the predefined time window, wherein the first baseline of blocks and the newer blocks are initially stored in the premium storage area and wherein the older blocks are initially stored in the low-end storage area; providing a direction signal in response to receipt of a restore command to restore the set of files at a particular time of the multiple different times within the predefined time window from the collection of blocks stored within the storage subsystem, the direction signal having (i) an older direction value indicating an older direction when the particular time is older than the first baseline time and (ii) a newer direction value indicating a newer direction when the particular time is newer than the first baseline time; from the collection of blocks stored within the storage subsystem, forming a second baseline of blocks from the first baseline of blocks and additional blocks, the additional blocks being either (i) the older blocks or (ii) the newer blocks depending on whether the direction signal has the older direction value or the newer direction value, and the second baseline defining the set of files at the particular time; replacing the first baseline of blocks with the second baseline of blocks in the premium storage area; and transferring the replaced first baseline of blocks to the low-end storage area.