I would recommend using separate HBA ports for disk and tape.   This is 
especially so if your disks have any kind  of dual-path software.

The driver parameters for disk with failover will be different from tape; 
notably timeouts will be different.   There are for some HBAs settings to 
help with tape device recovery, they may not suit disks.

I'm not aware of any dual-path software for tapes.

And of course, if you hang a couple of LTO2 tapes on the fibre (35MB/s), 
and have data that backs up at 2:1 compression (so 70MB/s)...you are going 
to use a lot of the fibre.  That may not make disk performance good.

William D L Brown