FreeNAS: The Free NAS Server

FreeNAS isĀ a freeĀ NAS (Network-Attached Storage) server, supporting: CIFS (samba), FTP, NFS, RSYNC protocols, local user authentication, Software RAID (0,1,5) with a Full WEB configuration interface. FreeNAS takes less than 16MB once installed on Compact Flash, hard drive or USB key.
The minimal FreeBSD distribution, Web interface, PHP scripts and documentation are based on M0n0wall.

Link