07/15/86  adjust_mrds_db, amdb


Syntax as a command:  amdb path {-control_args}


Function:  This DBA tool handles special problems that may arise
involving the data base concurrency control segment.  It may be used to
re-establish consistency in concurrency control after an incomplete
data base operation has put the data base in a potentially invalid
state.  It may also be used to remove dead process information from the
control segment or to change the setting of the concurrency control
trouble switch.


Arguments:
path
   is the relative or absolute pathname of the data base whose
   concurrency control segment is to be manipulated.  The .db suffix
   need not be given for new version data bases.  This cannot be a
   submodel pathname.


Control arguments:
-dead_procs, -dpr
   the data base control segment removes any information pertaining to
   dead processes (data base openers whose processes terminated without
   closing the data base).  Non-passive dead processes (processes with
   some form of update scope set) may leave the data base in an
   inconsistent state.
-force, -fc
   suppresses the query given for the -reset control argument.
-no_force, -nfc
   allows the query for the -reset control argument to be given.
   (Default)


-reset, -rs
   the data base control segment is re-established in a consistent
   state.  If there are active users of the data base, the command
   queries the user whether to continue, since other active users
   lose concurrency control protection if this invocation proceeds.
   (Default)
-trouble_switch state, -tsw state
   where state may be either "on" or "off".  This sets the data base
   concurrency control trouble switch to on or off.  If the switch
   is on, attempts to open the data base fail.  This can be used to
   lock out users when there is a question about the data base
   integrity.  The DBA can then restore damaged segments or rollback
   the data base to a consistent state.


Notes:  The user must be a DBA to use this command.


The -reset and -dead_proc options may not be used together.  The -force
and -no_force control arguments, given without -reset, imply -reset.


The -reset option (default) should be used only after
display_mrds_db_status is invoked, to determine if there are open users
and to notify those users to close their opening of the data base.  If
open users are active during use of this option, they lose concurrency
control protection and later inconsistencies may arise.


The use of the -reset option causes version 4 concurrency control,
using the read-update scope modes, to be updated to version 5
concurrency control using the scope modes read_attr, modify_attr,
append_tuple, and delete_tuple.  Version 5 concurrency control uses a
segment named db.control rather than dbc.  Version 4 concurrency
control cannot be used with the current version of MRDS, and
adjust_mrds_db with the -reset option must be used on the data base in
order to convert it to version 5 concurrency control.  The current
version of concurrency control may be displayed via
display_mrds_db_status using the -long option.


Current users of r-s-m-d scope mode encodings do not have to change
their application programs to use version 5 concurrency control.
Application programs calling dsl_$set_scope or dsl_$set_scope_all which
use the old r-u scope mode encodings need to be changed to the
encodings described in the MRDS manual (e.g., 2 no longer means s-m-d,
just s).


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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