PowerEdge R6615 Supported Drives

Internal drive bay and hot-plug backplane:
Up to 10 x 2.5” HDD: SAS, SATA, Near-line SAS SSD: SAS, SATA 
Up to 4 x 3.5” HDD: SAS, SATA, Near-line SAS SSD: SAS, SATA 

Up to 16 x EDSFF E3.S Gen5 NVMe (SSD)

Datasheet: R6615 spec sheet