Dell DSS 2500 Owner's Manual page 132

Figure 69. Cabling between the hard drive backplane and RAID controller on internal PERC riser and internal hard drive
connections
1 internal hard drives (2)
3 system board
5 SAS B connector on RAID controller
7 SAS B connectors on backplane
132 Installing and removing system components
2 internal SATA connector
4 SAS A connector on RAID controller
6 backplane
8 SAS A connectors on backplane