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                    D2D - A Disk to Disk Utility

                   Coordinated Science Laboratory
                       University of Illinois
                         Urbana, Ill. 61801

With D2D it is possible to transfer files from one disk structure to
another.  One advantage of D2D over other programs is that the
destination structure need not have UFD's defined. It is possible to
copy an entire structure without actually naming the PPN's to be
transferred.  All SFD's are properly copied.  When D2D is used in
conjunction with DCRPE and TWICE, all of the functions of formatting,
refreshing, and copying disks can be done in a timesharing mode.

Using D2D is equivalent to doing a FAILSAFE save to magnetic tape, a
refresh, and a restore using FAILSAFE, however it is faster and more
reliable.  Copying is done to recover "lost" blocks and to optimize
disk file placement.  "Lost" blocks are blocks which the monitor
thinks are in use but are not actually in any file. File placement is
improved because new files are written contiguously on disk. D2D will
copy files from one disk structure to another without regard for
whether the structures are different sizes.  Thus, no special
considerations are necessary when both structures are single RPO4's
or single RPO3's.  Furthermore, a 2 RPO3 structure can be copied to a
single RPO4 or vice versa.  Although it has not been tried, D2D
should be able to copy a 3 RPO4 structure to a 6 RPO3 structure, for
example.  The combinations are many. Copying one rather full RP03
structure to another takes about 40 minutes.

However, consider that the system disk (DSKB) consists of a RPO4 and
it is desired to maintain a backup RPO3 DSKB consisting of only the
most essential files.  D2D can optionally copy only the PPN's
specified during its execution permitting the user (System
Administrator) to extract the PPNs of his choice.


The destination structure may be mounted single access to prevent
unwanted UFD's from appearing. The source structure can be mounted
single access if it is important that no editing be permitted (which
might not be copied to the destination structure). It is not
necessary to mount either source or destination /SINGLE access.

	.Mount DSKJ (/SINGLE)

	.Mount DSKC (/SINGLE)

Assuming that a structure called DSKJ exists and is physically
mounted, the copying can begin.  OMOUNT may complain that the pack id
is incorrect; if so, the operator should tell it to proceed anyway.

	.R D2D

	Input Disk: DSKC

	Output Disk: DSKJ

	PPN to Transfer:

<CR> means entire disk structure.  If PPN's are specified, they must
be in square brackets, entered one per line. In this mode a lone <CR>
will terminate the copying. If the whole pack is being copied, D2D
will now copy all files (including UFD's and SFD's) from DSKC to
DSKJ.  This takes about 40 minutes on an RP03. D2D will print out the
name of every UFD after it has transferred files in that UFD, as a
check on its progress.  If you want to see how much further D2D has
to go, you can do a "DIRECT DSKC:[1,1]/L" under another [1,2] job
which will print out all UFD's that must be copied.

D2D will print an error message if it cannot copy a file.  Usually
this means the file was bad, and nothing valuable has been lost.
However, if this happens you should notify the user, and if he wants,
restore the file from a FAILSAFE tape.  You may also get a message
"?Cannot enter UFD for [xx,xx] code (2)" or similiar; this means D2D
tried to create a non-system UFD which for some reason already
existed.  If no other errors occur, this one can be ignored. All
files will be copied, possibly overwriting existing files for PPN's
which have UFD's on the destination device. Any other error messages,
particularly D2D bombing out, should be reported to a systems

	Do you want to change file structure name?

This is useful if the new pack(s) is(are) to be used as a structure
which is currently on the system.  D2D will rename any structure
currently spinning, thus be sure of what you are doing when
responding "yes" to this question. If the answer is "no", D2D will

	(If "yes")
	Do you want D2D to remove <STRNAM>?  (<STRNAM> will be the
structure being renamed.  The usual response would be "yes". A "no"
would merely suggest using OMOUNT.  Finally, the new structure name
is requested, the renaming occurs, and D2D exits.)


Note that the new structure probably has no copy of BOOTS, so it may
be good practice to run WTBOOT after D2D.

It is useful to have several spare structure names defined in
STRLST.SYS for use when copying or renaming.  Since OMOUNT checks to
see if the right type of drives are available, structures should only
be named to agree with those defined in STRLST.

If the destination and source disks contain no swapping space, it is
possible to dismount the old and mount the new. Otherwise, the new
structure cannot be used without crashing the monitor.

In case the new copy of the file structure seems to be unusable, you
can go back to the old copy. If only one file seems to be unusable on
the new structure, you can mount the old copy of the file structure
under a different name (DSKJ is convenient) while still keeping the
new copy on the system. OMOUNT will complain bitterly when you do
this, but keep telling it to proceed and eventually it will do the
mount.  Then copy the bad file from DSKJ to the new file structure:


For further information,
Contact: Tom Burtnett
Programmers: Steve Fortune
	     Peter Dewolf

DECUS # 10-256