Error: Do not have sufficient voting files - Restoring Voting Disk

 MOS article 428681.1 should be your starting point to add a vote disk in your RAC based on the version of RAC you are using and where you are storing your voting disk. In an Oracle RAC environment, it is recommended to store voting disk on a diskgorup with normal or high redundancy and have 3 copies of voting disk. During installation you can select the number of voting disks you want to create, or you can add extra copies later. If you have 4 physical disks in an ASM diskgroup with normal redundancy, you can choose to have 4 copies of vote disk and Oracle would create 4 voting disks on each physical disk of the diskgroup. In case of one or two disks failure, you would still have 2 voting disks copies to start the RAC. There is also a requirement of having at least 2 voting disks in order to start your RAC, otherwise RAC resources would not start up.