SnapRAID is a backup program for disk arrays. It stores parity information of
your data and it recovers from up to six disk failures.
SnapRAID is mainly targeted for a home media center, where you have a lot of
big files that rarely change. Beside the ability to recover from disk failures,
the other features of SnapRAID are:

* You can use disk already filled with files, without the need to reformat them.
  You will access them like now.
* All your data is hashed to ensure data integrity and to avoid silent
  corruption.
* If the failed disks are too many to allow a recovery, you lose the data only
  on the failed disks. All the data in the other disks is safe.
* If you accidentally delete some files in a disk, you can recover them.
* The disks can have different sizes.
* You can add disks at any time.
* It doesn't lock-in your data. You can stop using SnapRAID at any time without
  the need to reformat or move data.
* To access a file, only a single disk needs to spin, saving power and producing
  less noise.

WWW: http://www.snapraid.it/