There seems to be some confusion here as to whether the original question relates to FAST (full LUN movement) or FAST VP (subLUN movment) so I will address both.  For both FAST and FAST VP a tier definition is based on a drive technology and a RAID protection type.  While drives of different speeds and sizes may be included in the same tier definition, the RAID protection must be the same.  When creating a policy, however, behaviors are different for FAST and FAST VP.  If a FAST policy contains two tiers of the same technology, but different RAID protection types, it is possible that performance related movements will be generated between the two.  These movements will not be promotion/demotion type movements, they will actually be based on load balancing.  If a FAST VP policy contains two tiers of the same technology, but different RAID protection types, there will be no performance related movements between these two tiers.  FAST VP only differentiates performance based on drive technology.  As such, there is no benefit to putting two tiers of the same technology into the same policy.  For the original question, if the question relates to FAST, then a policy can be created containing the two FC tiers and FAST will attempt to load balance between the two.  If the question realtes to FAST VP then creating a policy will deliver no benefit, as no performance related movements will occur.
hi i have two tier on my VMAX FC_Raid 1  with 300GB 15K FC_Raid 6  with 450 GB 10 K  can FAST work on different tier both are FC
FAST with two FC tier