HPE SimpliVity calls the tie-breaker "arbiter". The use of the arbiter automates failover decisions in order to avoid split-brain scenarios like network partitions and remote site failures. The arbiter can be either on-premises or hosted as a cloud instance, and is recommended but not a hard requirement. The arbiter is a small Windows service, so it can run about anywhere, as long as it has network access to both active sites. A single arbiter may be shared by multiple clusters in the federation. Installing an additional arbiter for every 4,000 virtual machines helps ensure best performance and distributes workloads.

In VMware vSphere environments the arbiter is a hard requirement for 2-node clusters and stretched cluster configurations. Furthermore, HPE recommends using the arbiter in non-stretched cluster configurations with 4 HPE OmniStack hosts.

Currently for Microsoft Hyper-V environments (2-node clusters) the arbiter is a hard requirement.

The HPE OmniStack 3.7.9 version of Arbiter introduced support for clusters with hosts that use HPE OmniStack 3.7.8 and other clusters with hosts that use HPE OmniStack 3.7.9. The federation can contain a mix of clusters with those two versions. However, all the hosts within the same cluster must use the same version.