PowerEdge R520 Supported Drives

Internal drive bay and hot-plug backplane:
Up to 8 x 2.5” HDD: SAS, SATA, Near-line SAS SSD: SAS, SATA
Up to 8 x 3.5” HDD: SAS, SATA, Near-line SAS SSD: SAS, SATA 

Datasheet: R520 spec sheet 

PER520