03/28/87  copy_disk_volume

Syntax as a command:  copy_disk_volume  source_device_name
                        target_device_name  {-control_args}


Function: copies data from one Multics physical volume to another of
the same device type when the source is a system-storage disk and both
disk packs are mounted on non-system-storage (I/O) disk drives.  This
command can be used to recover data from a failing disk pack without
shutting down the system.


Arguments:
source_device_name
   is the name of the disk drive to be copied from, in the form
   dska_xx{s}.
target_device_name
   is the name of the disk drive to be copied to, in the form
   dskb_xx{s}.


Control arguments:
-brief, -bf
   suppresses the informative messages produced by default.
-check, -ck
   causes the target disk to be written in "wrtcmp" mode, which uses
   write-compare DCWs to do the writing.
-error_threshold {N}
   sets the threshold for number of bad pages allowed on the disk
   before you will be queried whether or not you wish to continue
   copying.  (Default 10).
-long, -lg
   prints informative messages at the beginning and end of the copy,
   and announces the location after every hundred cylinders are copied.
   (Default)


-no_check, -nck
   writes the target disk using ordinary write DCWs. (Default)
-no_query
   no queries will be issued.  If -no_query is used in conjunction with
   -error_threshold, when the threshold is reached, the program will
   exit.
-no_trace
   suppresses the trace messages. (Default)
-pv_name name, -pv name
   optional argument to allow specification of a volume name for
   either the source_device or the target_device.  This argument is
   considered a modifier for either source_device_name or
   target_device_name and must appear after the device name to which it
   applies.  For example:


   copy_disk_volume dska_nn{s} -pv foo dska_nn{s}
   copy_disk_volume dska_nn{s} dska_nn{s} -pv bar
   copy_disk_volume dska_nn{s} -pv foo dska_nn {s} -pv bar

   If no pv_name is given, the default pv_name "scratch" will be used
   in the attach description for the volume.

-query
   allows issuing of queries and the chance to respond with an
   appropriate answer.  (Default).


-trace {N}
   prints a message for every N I/Os performed by copy_disk_volume,
   giving the disk name, elapsed time, sector number, and length.
   N is an optional parameter designating the increment for number of
   I/Os (default 1).  The trace is off when copying in page-mode on a
   retry after an unrecoverable read error.


Notes:

Access required -  Access to workspace.acs is required so that large
DCW lists can be used.  Access to the dskX_NN.acs segments for the disk
drives is required.  Access to rcp_sys_ is required in order to attach
system storage volumes.

Error Recovery -  When an error occurs while reading the source disk,
copy_disk_volume retries the I/O by breaking it into single records.
Errors in writing the target disk will cause the program to exit.  Any
errors which persist during single record I/O are considered
unrecoverable, the record is skipped and an error message is printed
with information about which sectors of the disk are unreadable.


The use of very large I/O buffers requires that only one copy of
copy_disk_volume be performed at a time in a given process.  It is also
recommended that this command not be performed from the initializer
because of the I/O requirements.


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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