I just installed 4 X 2Tb WD20EARS-00S8B1 in Raid5 in a new DS410 and everything went fine.
I'm a little worried about the SMART cycle count which is already at 4000+ after one day but from what I read it should not make my drive fail, unless I'm mistaken.
The transfer speed seems OK. I tested writing a 25Gb file and it's about 20% faster than my old DS409 with 4X WD1001FALS-00J7.




