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BACKUP COMMAND
3.2 -- Diskette
Cop~ing
sou~ce
diskette
on
the
destination
diskette.
Only
the
allocated space from the source diskette will be copied.
The
allocated space includes all file space· and all areas
locked
out in the Lockout Cluster
Allocation
Table
(see Chapter
24).
Thus,
only MDOS-generated diskettes can be copied
using
the
BACKUP
command,
since
other
diskettes
will
not
have an
allocation table.
Since only. the allocated space is
copied;
the
minimum
amount
of
disk
space
is copied, and the BACKUP
p~ocess
is
completed in the minimum amount of time.
Sometimes,
however,
it
is
desirable
to
obtain a complete copy, and not Just a
copy
of
the allocated space.
In
such cases, the
"U"
option
can be used to
fo~ce
the copying of unallocated space as well
as
the allocated space.
A typical BACKUP
process
dialogue would
look
like
the
follouling:
=BACKUP
BACKUP FROM DRIVE 0 TO 1?
y
=
and
would
produce a copy on the destination diskette of the
source diskette's allocated space.
If
an EXORdisk
III
system
is
being'
used,
then
the
destination diskette cannot
be
a single-sided diskette
ir
the
source
diskette
is
a
double-sided
diskette.
The
error
message:
INVALID TO COPY/VERIFY FROM DOUBLE TO SINGLE SIDED
will
be
displayed
and control
~eturned
to MDOS to indicate
this condition.
The opposite,
however,
is allowed.
That iSI
a
single-sided
diskette
can
be
in the source drive with a
double-sided diskette in the destination drive.
3.3 File Reorganization
After an MDOS diskette has been used Tor
a
while,
the
Tile structure may become fragmented and new riles can become
scattered.
The longer a diskette is used
in
a
development
environment,
the
more
the
total system perTormance may be
degraded due to increased access time.
File
reorganization
is
supplied by the
BACKUP
command and constitutes one way to
restructure MDOS diskettes,
thereby
improving
the
system's
@TTiciency.
Page
03-03
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