Abstract: Block-based backups for sub-file modifications are described. A system records an identifier of a modified file into a file modification journal. The system records an identifier corresponding to a modified block in a file system into a modified block map. The system creates a modified file block map based on the identifier of the modified file in the file modification journal. The system identifies a modified file block corresponding to the modified file based on an intersection of the modified block map and the modified file block map. The system reads the modified file block from the file system using a file system read interface. The system writes the modified file block to a backup storage.

Abstract: File-based snapshots for block-based backups are described. A system records an identifier corresponding to a modified block in a file system into a modified block map. The system creates a modified file block map based on a modified file. The system identifies a modified file block corresponding to the modified file based on an intersection of the modified block map and the modified file block map. The system creates a mounted backup image by mounting a previously created block-based backup of the file system onto a proxy host. The system enables a forward snapshot of the mounted backup image. The system reads the modified file block from the file system using a file system read interface. The system creates a forward snapshot file for the modified file by writing the modified file block to the mounted backup image using a file system write interface.