When you start a scheduled backup group manually (on demand), Backup runs the backup at the level of the next scheduled backup, which can be full, level 1-9, or incremental.
To immediately start a group backup in one of two ways:
In the Backup administration program, click the Start Now button in the Group Control window.
From the command line, become root on the Backup server, then issue the savegrp group-name command at the shell prompt.
When you use the Start Now control, Backup overrides the Groups scheduled start time and immediately backs up the clients in the group.