I believe the following is correct, but you may want to check a bit
further. For myself, I've never had a problem burning CDs whether I
defragged first or not:
The technical answer is...it depends.
The CD burning process must run without significant pause, or chances
are great that the resulting CD will be unusable.
If the CD writer software is the usual kind, it will establish a buffer
space in RAM for files to be burned to the CD. It then starts to read
the source files to be written from elsewhere, one by one, and starts
writing the CD from this buffer. As the buffer "empties" it is filled
with more source until the writing process is completed. If the source
files are heavily fragmented, filling the buffer and keeping it full
will slow the writing process, but usually won't do damage. To be on the
safe side, and get optimal CD writing performance, it's best to defrag
the files you want to burn beforehand. (If the buffer refilling is so
slow that the buffer actually empties before the job is done, then you
have a bad CD. This doesn't happen very often.) In the above scenario,
files on the CD will be contiguous, not fragmented, even it they're
fragmented on the source medium. The buffer loads one complete file at a
time, so files as written to the CD are contiguous.
If you are using a CD writing process that copies an actual
byte-for-byte image of the source to the CD, then the actual structure
of the source files is maintained on the CD. Fragmented source files
will be fragmented on the CD. So in this case especially it's best to
defrag before burning.
