Patent ID: 7979396

Claim:
A method comprising: applying, to a first storage device, a plurality of first modifications to information stored on a second storage device; performing change tracking, wherein the change tracking comprises identifying regions of the first storage device that have values differing from values stored on the second storage device as a result of the first modifications without identifying the order in which different regions are modified, and setting a bit in a bitmap for each identified region, wherein the bitmap comprises a plurality of bits, each bit corresponds to a respective region of the first storage device, and the bit is cleared when the respective region corresponding to the bit is synchronized with the second storage device; detecting that connectivity to the first storage device has been lost, wherein modification logging is inhibited prior to the detecting; in response to the detecting, initiating the modification logging, wherein the modification logging continues until connectivity has been restored and the first storage device has been synchronized with respect to the second storage device, the modification logging is performed at a smaller granularity of information than the change tracking, and the modification logging comprises: detecting a plurality of second modifications to information stored on the second storage device, wherein information stored on the first storage device is a synchronized copy of the information stored on the second storage device, prior to the time at which the plurality of second modifications are applied to the second storage device, and storing information indicating an order in which the second modifications occur to the second storage device; and in response to the detecting, inhibiting the change tracking, wherein the change tracking is inhibited as long as the modification logging continues.