sp_volchanged allows you to include the name of a specific Backup Server. The syntax is:
sp_volchanged session_id, devname, action [, fname [, vname] [, backup_server_name]]
For example, this specifies that a volume change request is made on Backup Server Inst3_BS:
sp_volchanged 5, "db1.dmp", "proceed", "Inst3_BS"
If you do not include the name of a Backup Server with the $DEDICATED or $ROUNDROBIN method, sp_volchanged raises an error.