User space RAID-6 access

Hi all,

some times ago, I think was Neil, it was mentioned
about the possibility to access consistently a RAID-6
array from user space, in order to be able to perform
some checks, like the notorius "which HDD has wrong data".

Is there any reference or documentation or source code
which can be taken as example for such a case?

Thanks,

bye,

-- 

piergiorgio