Using this Project FreeNAS you can build your own storage box at Work or home easily, realiably.
FreeNAS is a free NAS (Network-Attached Storage) server, supporting: CIFS (samba), FTP, NFS, AFP, RSYNC, iSCSI protocols, S.M.A.R.T., local user authentication, Software RAID (0,1,5) with a Full WEB configuration interface. FreeNAS takes less than 32MB once installed on Compact Flash, hard drive or USB key.
You can run it from USB key and leave your hard drives to be used as NAS, nevertheless you can make a partition dedicated to FreeNAS OS and application and use the rest as NAS.
I did not have the chance to test it , but last time it was good enough to use it.
The minimal FreeBSD distribution, Web interface, PHP scripts and documentation are based on M0nowall.
FreeNAS project caould be found h3r3