When you dump the master database, be sure that the entire dump fits on a single volume, unless you have more than one SAP ASE that can communicate with your Backup Server.
You must start SAP ASE in single-user mode before loading the master database. This does not allow a separate user connection to respond to Backup Server volume change messages during the load. Since master is usually small in size, placing its backup on a single tape volume is typically not a problem.