Clonezilla

Clonezilla is a wildly aggressive, globally ubiquitous open-source leviathan that completely attacked the "Massive Lab Deployment" market. It has zero graphical user interface (GUI). It runs entirely in a terrifying, DOS-like command-line environment. It is the absolute, unquestioned weapon of choice for University IT departments, Linux sysadmins, and massive server farms that need to mathematically blast a single master disk image onto 400 bare-metal computers simultaneously over a local network. Its absolute biggest differentiator is "The Multicast Mathematical Broadcasting." If an IT admin needs to image 40 computers, doing it one by one takes 40 hours. Clonezilla SE (Server Edition) uses Multicast networking mathematics. The master server mathematically blasts the single disk image across the LAN. All 40 computers receive the exact same packets simultaneously. Imaging 40 computers takes the exact same mathematical amount of time as imaging 1 computer, completely eradicating deployment bottlenecks. Because it targets hardcore sysadmins, its "Raw Sector Mathematics" is legendary. Most commercial tools refuse to image a hard drive with a corrupted file system. Clonezilla doesn't care. It can operate in a raw 'dd' mode. It bypasses the file system entirely and mathematically copies the physical 1s and 0s directly from the platter of the drive, making it the absolute weapon of choice for digital forensics and data recovery experts attempting to clone dying, heavily corrupted mechanical hard drives.