Since the shared disk environment cannot be used in AWS environment, you cannot use SCSI reservations to prevent a split-brain. Also, IP resource may cause the split-brain as it uses the real IP resource with different IP addresses for each node.
For this reason, please consider the use of Quorum/Witness server or STONITH, an I/O fencing function of LifeKeeper to use this configuration safely.
Especially, because you can implement I/O fencing function separately without the Quorum server if you use the TCP_REMOTE setting in Quorum mode, it is easy to be implemented in the cloud environment. For more details, please refer to the following URLs: