A. SCR doesn't use failover clustering, which means you don't need to fail over an entire resource group. This differs from technologies such as Single Copy Cluster (SCC) and Cluster Continuous Replication (CCR), which use failover clustering and implement a clustered mailbox server that fails over all storage groups on the server.
With SCR, you can selectively fail over storage groups from the source server to one of the SCR replicas because with SCR, you can have multiple replicas of a database.
There are some considerations, however, that may make you want to move all storage groups on a source to the same SCR replica. For example, if you have a source server that's part of a cluster, then ideally you would move all the storage groups to the same SCR replica so that you can use the recovercms approach to start the replicas on the target.
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