FreeNAS is a free NAS Server, supporting CIFS (Samba), FTP, NFS, Rsync protocol, local user authentication and software RAID (0, 1, 5) with full Web configuration interface. FreeNAS takes less than 32MB once installed on compact Flash, hard drive or USB key.

Features :-

1. Filesystem: UFS, FAT32, ext2/ext3, NTFS (As of 0.684b the homepage says: "NTFS: Replace ntfs FreeBSD module with ntfs-3g: read/write support for NTFS")
2. Protocol: CIFS (samba) , FTP, NFS, SSH, RSYNC, AFP, and UPnP.
3. Hard drive: ATA/SATA/PATA, SCSI, iSCSI, USB and Firewire.
4. GPT/EFI partitioning for hard drives larger than 2 Terabytes.
5. Networks cards: All wired and wireless cards supported by FreeBSD 6.
6. Boot from HDD, USB key, Compact flash, CD-rom + floppy disk.
7. Hardware RAID cards: All those supported by FreeBSD 6.
8. Software RAID levels: 0, 1, 5, JBOD, 5+1, 5+0, 0+1, 1+0, etc. (using GEOM)
9. Management of groups and users (Local User authentication or Microsoft Domains)
10. Unison support.
11. S.M.A.R.T. support.

NAS differs from the traditional file serving and Direct Attached Storage in that the operating system and other software on the NAS unit provide only the functionality of data storage, data access and the management of these functionalities. Furthermore, the NAS unit does not limit clients to only one file transfe protocol. NAS systems usually contain one or more hard disks, often arranged into logical, redundant storage containers or RAIDs (redundant arrays of independent disks), as do traditional file servers. NAS removes the responsibility of file serving from other servers on the network and can be deployed via commercial embedded units or via standard computers running NAS software. NAS uses file-based protocols such as NFS (popular on UNIX systems) or SMB (Server Message Block) (used with MS Windows systems). Contrast NAS's file-based approach and use of well-understood protocols with storage area network (SAN) which uses a block-based approach and generally runs over SCSI, Fibre Channel or iSCSI. (There are other SAN protocols as well, such as ATA over Ethernet and HyperSCSI, which however are less common.)