a) 1 Host with "2" FC ports (1 dual FC card or 2 mono port FC card, it doesn't matter anyway).
For redundancy reasons you would configure these 2 FC port to access disk. So you zone each port to disk array ports, each on on a different SAN fabric.
Now, if I wanted to backup to tape (LAN Free) and couldn't add more hba cards to that machine, could I use those 2 ports to access tape as well ?
Using the FC ports for both disk and tape could also increase the machine overall performance since I would be using the full duplex capability of the FC protocol. So if I had a machine with 4 FC ports I could have 44Gbit/s for disk and 44Gbit/s for tape instead of 24 + 24.
The configuration is not recommended & supported by IBM. The DISK ERRORS & ADAPTER ERRORS are encountered on AIX due to this configuration, especially during the backup window of server.