Comprehensive and Detailed Explanation From Exact Extract of Nutanix End User Computing documents:

According to the Nutanix Files Guide regarding Data Replication and VDI solutions:

VDI Sync Functionality: VDI Sync is the specific feature designed to replicate VDI user profiles and data across file servers in different locations (active-active). It ensures that user profile data (like FSLogix or UPM containers) is synchronized in near real-time, allowing users to roam between sites and access their data locally at either location.

Smart DR distinction: Smart DR (Option C) is primarily a Disaster Recovery solution (Active-Standby) used for share-level replication and failover in the event of an outage. It is not designed for the active-active, bi-directional roaming of user profiles required by the question.

Use Case: For a distributed VDI environment where a user might log in to Site A today and Site B tomorrow and needs their profile immediately available and writable in both, VDI Sync is the mandatory component.