Patent ID: 7945749

Claim:
An apparatus, comprising: a first storage device to store user data and comprising: a controller to control the first storage device according to a process comprising: maintaining bit-map information, the bit-map information including a plurality of bits indicative of locations of the user data, the bit-map information including first flags indicative of updated portions of the user data, the plurality of bits of the bit-map information being divided into a plurality of groups of bits; maintaining rounded bit-map information, the rounded bit-map information including a plurality of bits, each bit of the rounded bit-map information being assigned to each group of bits of the bit-map information, the rounded bit-map information including second flags indicating that corresponding groups of bits of the bit-map information include at least one first flag; a second storage device for communicating with a host, comprising: a controller to control the second storage device according to a process comprising: maintaining a copy bit-map information indicative of locations of the user data to be copied; copying the user data based upon the copy bit-map information to the first storage device; receiving the rounded bit-map information maintained in the first storage device, upon receiving a copy resume command to resume the copying; acquiring a group of bits of said bit-map information maintained in the first storage device, based upon the rounded bit map information, wherein when a bit of the rounded bit-map information does not include any second flag, a corresponding group of bits of the bit-map information is not acquired; and updating the copy of the user data by accessing a location of the user data in the first storage device as indicated by the group of bits of the acquired bit-map information for synchronization of the copy of the user data with the user data in the first storage device.