The number of onboard ports vary for different models, so regardless of number of ports the use cases are as described:
Onboard Gbe ports: Available for host connectivity [e0a, e0b,e0c, e0d....]
Onboard FC: For SAN, also will be using FC disk shelves [0a,0b,0c,0d.....]
Onboard SAS: Some SAS tape drives are supported, but as you likely will be using SAS disk shelves
SCSI Connection: for connection to tape devices
InfiniBand: for cluster interconnect, now MTP cable is used with converter
Serial Console: For CE's to connect directly to filers by usind DB9 cables
RLM NIC: for remote management
There can be multiple modular expansion slots for expanding onboard ports and for Flash modules and all that good stuff
For ex:
2x FAS6280 w/ IOXM
- 6x X2067 – 4 port SAS adapter
- 2x X2065 – 4 port SAS adapter
- 2x X1971A-B – 512Gb FlashCache
- 2x X1971A – 512Gb FlashCache
- 20x 2m LC/LC Cables
- 2x 5m SAS Cables
- 2x Universal Rail Kits
Onboard Ports Target
2x FAS3240
- E0A/E0B in use
- 0a/0b – SAS Host
- 0c/0d in use as target
- 2x 256Gb FlashCache
- 3a/3b/3c/3d – SAS Host
- 4a/4d – SAS Host
Also you will be using 10 gig ports for connected HA pair's for snapvault traffic. Configuration changes from environment to environment depending on the requirement.