SAND CDBMS Administration Guide
Persistent Mode Operations (Time Travel)

Starting a Time Travel Database Instance

To start a database instance using a particular database Snapshot, include the -s flag in the nserv invocation command, followed by the number of the Snapshot to be used, as follows:

If the -s flag and Snapshot number are not provided, the current Snapshot will be started by default. The current Snapshot is normally associated with the Update File that has the most recent file modification timestamp. However, any Snapshot can be set to current Snapshot using the nmerge -e command. As well, if the current Snapshot is deleted (using the nmerge -d command), its parent in the database version tree becomes the new current Snapshot, even if it is not the most recent remaining Snapshot.