Clonezilla

Clonezilla boots from USB or DVD and creates an image of a disk or partition, or clones disk to disk, copying only used blocks. It supports Windows, Linux, macOS and BSD file systems, and falls back to a sector-by-sector copy for unknown ones. The Lite Server edition deploys one image to dozens of machines at once, useful in a computer lab or when setting up several identical workstations. Limitations: a text interface with a learning curve, no incremental backup, imaging must be done with the system offline, and the target partition must be equal to or larger than the source.