04/07/86  dm_set_journal_stamps

Syntax as a command:  dm_set_journal_stamps


Function: sets the time stamp for all journals currently in use to the
time at which the command is invoked.


Access required: You need re access to dm_admin_gate_.


Notes: The effect of altering the time to the present subverts the
write_ahead_log (WAL) protocol, which guarantees that modified control
intervals of protected data management (DM) files are not written to
disk until their before images have been safely stored in a before
journal.

Without the protection imposed by the time stamp, sync-held pages (as
modified control intervals are called when they are detained in main
memory) can be flushed to disk prior to their before images.  In the
event of a system crash without emergency shutdown (ESD), some before
images may not be available on rollback during recovery.


It may be necessary you invoke this command if before journals become
damaged, preventing transactions from being committed, or if there is
an unusually large number of sync-held pages, stalling system
performance.  This command provides a means of keeping the system
running instead of shutting it down.  Use this request only as a last
resort.


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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