Clonezilla

Filesystem supported: ext2, ext3, ext4, reiserfs, xfs, jfs of GNU/Linux, FAT, NTFS of MS Windows, HFS+ of Mac OS, UFS of BSD, and VMFS of VMWare ESX.

Therefore you can clone GNU/Linux, MS windows and Intel-based Mac OS, no matter its 32-bit (x86) or 64-bit (x86-64) OS. For these file systems, only used blocks in partition are saved and restored. For unsupported file system, sector-to-sector copy is done by dd in Clonezilla