Andrea Mazzoleni has been developing a new "SnapRAID" RAID engine that he's ported to the Linux kernel. The new library supports up to six parity levels while maintaining compatibility with the Linux RAID6 dual parity levels.
RAID parity is an error protection scheme for fault tolerance and now with this new RAID library by the SnapRAID developer there's support for six parities to offer greater reliability by being able to calculate the data difference across more than two disk drives. This new RAID support is based on a Cauchy Matrix.
With the new patch-set posted today for this RAID Linux kernel parity library, there's also a patch for the Btrfs file-system so that it's native RAID support can leverage this new code and provide for more than two parity levels with this next-generation Linux file-system.
Besides a standard C implementation of the RAID library, there's also a SSE2/SSSE3 version of the library too for greater performance on modern x86/x86_64 Linux systems.
Separate from the kernel library is the SnapRAID program itself, which is hosted on SourceForge. SnapRAID provides a back-up program for disk arrays that storages enough parity information to recover from up to two disk failures. SnapRAID is targeted for home media centers where there's many large files that rarely are changed.