Opportunistic locking is a feature of NCP Server that works to ensure that only one person at a time can open a file for write. In a DST shadow volume pair, NCP independently controls opportunistic locking for each volume. Users access files only via the merged view. There is no direct access by users to the secondary volume. When DST access a file on the secondary volume on behalf of multiple users, each request is related to the connection for a given user. NCP treats opportunistic locks for the request as if it came directly from the user.
For information about opportunistic locking and how it works, see Using Opportunistic Locking for NCP File Handling
in the OES 2015 SP1: NCP Server for Linux Administration Guide.