Restoring data from a storage device to a cloud service includes initializing each of a plurality of flags for each of portions of the data when the data is initially recalled from the cloud service to the storage device, the flags indicating whether a corresponding portion of the data has been modified while being stored on the storage device, modifying a particular one of the flags in response to a corresponding one of the portions being modified, transferring only portions of the data having corresponding flags that have been modified to migrate, and merging the portions of the data with remaining data at the cloud service. Data that is recalled from the cloud service to the storage device may be maintained on the cloud service. The portions of data that are transferred from the storage device to the cloud service may overwrite data maintained at the cloud service.