This article explains how delta pass works during a File Migration
The Cloudiway file migration platform allows unlimited delta passes (during 3 months). Each pass is considered a delta pass.
During a delta pass, the Cloudiway platform checks if a file has already been migrated. If it has, it compares the migration timestamp against the file’s last save time stamp, and if the file’s timestamp is more recent, it remigrates the file.
There is no delta pass for the migration of permissions.