See the S2600GP Technical Product Specification. There you'll see that there are different SAS and SATA ports on the board (page 5 & 6):
SATA 6G port 0
SATA 6G port 1
SATA 3G port 2
SATA 3G port 3
SATA 3G port 4
SATA 3G port 5
SCU0 Mini SAS port (0-3)
SCU1 Mini SAS port (4-7)
There's also Intel® RAID C600 Upgrade Key Options to support the On-Server Board SATA/SAS Capable Controllers (page 42). However, there's no key required to support RAID 5 with RSTe. But if you want more than 4 ports (Intel® RSTE 8 ports SATA R0,1,10 & 5) you need the RKSATA8R5 (White) C600 Upgrade Key Option.
You also need to use the <F2> BIOS Setup Utility, accessed during system POST, to enable/disable SW RAID, and select which embedded software RAID option to use.
For Intel® Rapid Storage Technology (RSTe):
- Supported RAID Levels – 0,1,5,10
- 4 Port SATA RAID 5 available standard (no option key required)
- 8 Port SATA RAID 5 support provided with appropriate Intel® RAID C600 Upgrade Key
- No SAS RAID 5 support (SATA only)