According to the manual, it's SATA standard, SAS optional, I guess that applies to whatever drives the chassis ships with. Looking in the bay it looks like it can take SAS physically, at least.
You can google all this or just find it
here, these are bog-standard Dells, the only slightly odd config I've found so far is combining the hot-swap drive backplane with the fixed non-redundant PSU, but other than that these are basically what you'd get if you called Dell and said "give me the cheapest thing you sell that does rackmount, iDRAC and I can put a sound card in it"