08/28/86  set_drive_usage, sdu

Syntax as a command:  sdu drive_name usage_type


Function: converts a disk drive from storage system use to user
input/output use or vice versa while the system is running.  You can
use it in ring 1 or 4.


Arguments:
drive_name
   is the name of the drive whose use is to be changed.  It has the
   form <subsys>_<nn>, e.g., dska_05.
usage_type
   can be one of the following:
   io
      converts the specified drive to user input/output use.  This
      drive must be a storage system drive.  The drive cannot have a
      known or accepted physical volume on it; if one is present, use
      the del_lv and del_vol commands to remove it before issuing this
      request.  Once converted, this drive remains a user input/output
      drive until you issue sdu again.


   storage_system, ss
      converts the specified drive to storage system use.  This drive
      must be a user input/output drive.  The drive cannot be assigned
      to any process; you can use the rcp command to find out.  You can
      use the "x deny" command to forcibly remove the drive from any
      user process to which it may be attached.  Once converted, this
      drive remains a storage system drive until you issue sdu again.


Notes: Drives in use by the storage system appear as "storage system"
to rcp, which means that they are unavailable for users.  Drives
assigned to user input/output use appear as "(io drive)" to the
list_disks command.


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Historical Background

This edition of the Multics software materials and documentation is provided and donated
to Massachusetts Institute of Technology by Group BULL including BULL HN Information Systems Inc. 
as a contribution to computer science knowledge.  
This donation is made also to give evidence of the common contributions of Massachusetts Institute of Technology,
Bell Laboratories, General Electric, Honeywell Information Systems Inc., Honeywell BULL Inc., Groupe BULL
and BULL HN Information Systems Inc. to the development of this operating system. 
Multics development was initiated by Massachusetts Institute of Technology Project MAC (1963-1970),
renamed the MIT Laboratory for Computer Science and Artificial Intelligence in the mid 1970s, under the leadership
of Professor Fernando Jose Corbato. Users consider that Multics provided the best software architecture 
for managing computer hardware properly and for executing programs. Many subsequent operating systems 
incorporated Multics principles.
Multics was distributed in 1975 to 2000 by Group Bull in Europe , and in the U.S. by Bull HN Information Systems Inc., 
as successor in interest by change in name only to Honeywell Bull Inc. and Honeywell Information Systems Inc. .

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Permission to use, copy, modify, and distribute these programs and their documentation for any purpose and without
fee is hereby granted,provided that the below copyright notice and historical background appear in all copies
and that both the copyright notice and historical background and this permission notice appear in supporting
documentation, and that the names of MIT, HIS, BULL or BULL HN not be used in advertising or publicity pertaining
to distribution of the programs without specific prior written permission.
    Copyright 1972 by Massachusetts Institute of Technology and Honeywell Information Systems Inc.
    Copyright 2006 by BULL HN Information Systems Inc.
    Copyright 2006 by Bull SAS
    All Rights Reserved