A method and apparatus for replicating data in a computer system having a plurality of sites is provided. Data stored at a first site is organized as one or more sets of formatted data. A mapping is created between subsets of data within the sets of formatted data and one or more object groups. These logical mappings to object groups allow distribution of the subsets of data at a finer level of granularity than previously provided and allow the subsets of data to potentially span multiple sets of formatted data. For each of the object groups, a replica of each subset of data that is mapped to the object group is created at one or more replication sites. When a data modification is detected to a subset of data that has been mapped to one of the one or more object groups, the data modification is propagated to the corresponding replication sites.