Why does Oracle Clusterware use an additional heartbeat via the voting disk, when other cluster software products do not?
Oracle uses this implementation because Oracle clusters always have access to a shared disk environment. This is different from classical clustering which assumes shared nothing architectures, and changes the decision of what strategies are optimal when compared to other environments. Oracle also supports a wide variety of storage types, instead of limiting it to a specific storage type (like SCSI), allowing the customer quite a lot of flexibility in configuration.
