Assuming a 7 mode system:
sysconfig -ca will show you what part is in each slot, and by elimination you can tell what slots are free, in my lab slot 3 and 4 are open. This command is great for knowing what the NetApp part number for your cards is as well!
Assuming a Clustered OnTap system
system node run -node <NODENAME> -command sysconfig -ca
sysconfig -ca
sysconfig: slot 5 OK: X1936A: Performance Acceleration Module I
sysconfig: slot 6 OK: X1107A: Chelsio S320E 2x10G NIC
sysconfig: slot 1 OK: X3148: NetApp NVRAM6 2GB
sysconfig: slot 2 OK: X2054A: QLogic ISP 2432; PCI-E quad-port Fibre Channel (QLE2464)
sysconfig: slot 7 OK: X2054A: QLogic ISP 2432; PCI-E quad-port Fibre Channel (QLE2464)
sysconfig: slot 8 OK: X2054A: QLogic ISP 2432; PCI-E quad-port Fibre Channel (QLE2464)
- Scott