Factors In CD Duplication

The process of writing data to a recordable CD can
be a complex process, as it demands a lot from both
hardware and software programs.  Much of this
complexity is hidden from the user by the program,
although you should be aware of these factors.

Data
The total amount of data you are writing is much
less important than whether or not it contains large
or several small files.  If there are a lot of
small files, the system may have problems with
locating and opening the files quickly enough to
send them smoothly to the CD recording drive.

The computer
Any interruption that may occur is fatal to CD
duplication, so you should ensure that your
CONFIG.SYS and AUTOEXEC.BAT don't load any TSR
utilities which may interrupt operations.  Screen
savers, alarms and reminders, or incoming faxes
may also kill disc writing.  You should also turn
off network sharing so no one will access the files
that you are trying to write, as this could also
kill your disc recording.

Hard Disk Speed
To write an image to the CD, the hard disk from
which you are writing must have a transfer rate
that is fast enough to keep the memory buffer full
in the CD recorder.  This normally means an average
hard disk access time of 19 MS or better.

Defrag
If your hard drive has to search everywhere over
a fragmented hard drive for the data to be written,
it can cause the operation to slow down or even
cause a fatal error.  Therefore, always be sure to
fragment your hard disk drive.

Recording speed
Most new CD recorders and even some older ones,
are capable of writing at two (sometimes even four)
times the standard playback.  It should be possible
for you to select the speed; as even though fast
recording is a time saver, it can also cause some
bad situations.

When you copy an ISO (image file) from the hard
disk to a CD, the speed is rarely a problem as the
image is already one large file in which the
files and structures are already in order and
divided into CD-ROM sectors. 

When you write from a virtual image, things can
get a bit trickier.  In order to copy to CD, the
program must consult with the database to find
where each file should go in the image and where
it is actually stored on the hard disk drive.

Then, it must open the file, divide it into CD-ROM
sectors, at the same time sending the data in a
smooth continuous stream to the recorder.  Locating
and opening the file is a bit more time consuming,
as writing is more difficult if you have a lot
of small files.