If one needs more than 9999 logical disk devices then another 'controller' may be used by specifying a new device at connection time: $ RUN SYS$SYSTEM:SYSMAN IO CONNECT LDA0/NOADAPTER/DRIVER=SYS$LDDRIVER IO CONNECT LDB0/NOADAPTER/DRIVER=SYS$LDDRIVER IO CONNECT LDC0/NOADAPTER/DRIVER=SYS$LDDRIVER