not good, because they are have many probems! I have 3*3tb and they are destroyed! Sector failure, shit! Afer a while I buy old 1tb from Hitachi with over 50.000 hours and build in 2008! Everything is okay and fine, so i should buy more ultrastar, it is for the future. The only one problem is, that they are very, very loud xD never 4tb! it's shit when you loose it!