will databases be mounted automatically?

Hi all,

here is our one DAG setup in one forest with three AD sites:  (Exchange 2010 SP1) and each site has domain controllers too

           MBX server      CAS/hub server     witness share                 DAGIP                  Databases hold

Site1:  MBX1 & MBX2;    CAS1 ;               \\cas1\dag01               198.168.0.10          MBX1: DB1, DB2 ; MBX2; DB3, DB4

Site2:  MBX3;                CAS2 ;               \\cas2\dag01 (alternate)172.18.0.10          DB1, DB2, DB3, DB4

Site1:  MBX4;                CAS3 ;               \\cas3\dag01               10.1.10.10             DB1, DB2, DB3, DB4

databases DB1 AND DB2 mounted on MBX1; DB3 AND DB4 mounted on MBX2; Activation preference for MBX3 is 2; Avtivation preference is 3.

If Site1 lost power and down, will databases DB1, DB2, DB3 & DB4 be mounted on the server MBX3 in site2?

Thank you for your help.