Methods, systems, and apparatus, including computer programs encoded on computer storage media, for resynchronizing data in a storage system. One of the methods includes determining that a particular disk of a capacity object of a storage system was offline for an interval of time, wherein the capacity object comprises a plurality of segments, and wherein the storage system comprises a segment usage table identifying a linked list of particular segments of the capacity object that are in use; determining a time point at which the particular disk went offline; determining one or more first segments of the capacity object that were modified after the time point, wherein determining one or more first segments comprises determining each segment of the segment usage table having a transaction ID that is larger than the time point; and resynchronizing, for each first segment, a portion of the particular disk corresponding to the first segment.