Storage Replica comes in three main configurations: stretch cluster, cluster-to-cluster, and server-to-server. There are different advantages to each.
The stretch cluster topology is ideal for workloads requiring automatic failover with orchestration, such as Hyper-V private cloud clusters and SQL Server FCI. It also has a built-in graphical interface using Failover Cluster Manager. It utilizes the classic asymmetric cluster shared storage architecture of Storage Spaces, SAN, iSCSI, and RAID via persistent reservation. You can run this topology with as few as two nodes.
The cluster-to-cluster topology uses two separate clusters. This topology is ideal for administrators who want manual failover or when the second site is provisioned for disaster recovery and not everyday usage. Orchestration is manual. Unlike stretch cluster, Storage Spaces Direct can be used in this configuration (with caveats - see the Storage Replica FAQ and cluster-to-cluster documentation). You can run this topology with as few as four nodes.
The server-to-server topology is ideal for customers running hardware that can't be clustered. It requires manual failover and orchestration. It's ideal for inexpensive deployments between branch offices and central data centers, especially when using asynchronous replication. This configuration can often replace instances of DFSR-protected File Servers used for single-master disaster recovery scenarios.
The server-to-server topology is ideal for customers running hardware that can't be clustered. It requires manual failover and orchestration. It's ideal for inexpensive deployments between branch offices and central data centers, especially when using asynchronous replication. This configuration can often replace instances of DFSR-protected File Servers used for single-master disaster recovery scenarios.
In all cases, the topologies support both running on physical hardware and virtual machines. When in virtual machines, the underlying hypervisor doesn't require Hyper-V; it can be VMware, KVM, Xen, etc.
Storage Replica also has a server-to-self mode, where you point replication to two different volumes on the same computer.