Clonezilla is a partition or disk clone tool similar to Norton Ghost. It saves and restores only used blocks in hard drive.
Two types of Clonezilla are available, Clonezilla live and Clonezilla SE (Server Edition). Clonezilla live is suitable for single machine backup and restore. While Clonezilla SE is for massive deployment, it can clone many (40 plus!) computers simultaneously. Clonezilla saves and restores only used blocks in the harddisk. This increases the clone efficiency.