In a clustered system both nodes need to have their target ports set to the same cfmode. To summarise the different cfmodes, which ones to use and where:
cfmode
Supported systems
Benefits and limitations
partner
All systems except FAS270, FAS60xx, and systems with 4-Gb adapters
Supports all host OS types.
Supports all switches.
single_image
All systems
Supports all host OS types.
Supports all switches.
Makes all LUNs available on all target ports.
dual_fabric
FAS270 only
Supports all host OS types.
Requires fewer switch ports.
Does not support all switches. Requires switches that support public loop.
standby
All systems except FAS20xx, FAS31xx, and FAS200 series
Requires more switch ports.
Supports only Windows and Solaris hosts.
mixed
All systems except FAS270c and FAS60xx
Supports all host OS types.
Does not support all switches. Requires switches that support public loop.