Patent ID: 7296125

Claim:
In a computer system having a mass storage device that stores data blocks, a method of creating a snapshot copy of selected data blocks, comprising the acts of: designating first data blocks of the mass storage device to be included in a snapshot copy that is to preserve the designated first data blocks as the designated first data blocks existed at a first point in time; marking second data blocks of the mass storage device as not protected so as to exclude the second data blocks from the snapshot copy; ensuring that the designated first data blocks are in a logically consistent state such that the first point in time corresponds to a time when no activity exists on the mass storage device; as the designated first data blocks at the mass storage device change after the first point in time, identifying specific data blocks of the designated first data blocks that change at the mass storage device; preserving a copy of only the specific data blocks of the designated first data blocks that change and not a copy of the data blocks of the second data blocks that change, wherein the preserved copy of the changed designated data blocks represents an original copy of the changed data blocks of the designated first data blocks prior to changing; backing up the designated first data blocks to the snapshot copy without interrupting access to the mass storage device; and providing access to the snapshot copy of the designated first data blocks.