A method and apparatus are disclosed for restoring a virtual disk (vdisk) in a data storage system as the vdisk was at an earlier time. Pointers are maintained to point to data represented by the vdisk. The pointers are saved to persistent storage at the earlier time. The data at the earlier time is maintained on the data storage device. A pointer pointing to data represented by the vdisk at a later time is compared with the pointers saved at the earlier time. If the pointer from the later time matches the pointer saved at the earlier time, keeping the pointer from the later time in the active file system. If the pointer from the later time does not match the pointers saved at the earlier time, copying a set of pointers associated with the pointer saved at the earlier time to the active file system.