> Hi,
> Just diverting the discussion a bit. Can someone
> tell me what difference it makes in burning an iso
> image and just merely copying files from a CD to
> another one?
> How does it affect the CD properties like whether it
> is bootable?
Well, first of all, the filesystem on a CD-ROM disc is ISO9660 format.
It is not the same as a computer filesystem. It was originally designed
in the Red Book specification for Audio CDs with extensions or
modifications defined in other specification docs like orange book /
yellow book.
Because of the incompatibility of the ISO9660 filesystem with a normal
computer filesystem, it becomes difficult to capture all the properties
of the CD on a computer filesystem. Hence you have special utils which
let you browse through the ISO filesystem like ISOBuster on Windows.
Fortunately, the mount command on *NIX has an ISO filesystem driver
which allows you to mount the ISO filesystem in the regular filesystem.
This, then, behaves as though it is part ot the computer filesystem.
But an Audio CD still cannot be mounted, because it does not contain
computer data as such - it contains music data.
Due to historical reasons or widely used formats, they retained the
ISO9660 filesystem even for computer CD-ROMs. But, again, as the
technology progressed, they found the basic ISO9660 filesystem
inadequate. So, they came up with modifications in the basic ISO
filesystem such as different modes to write CDs, Rock-Ridge extensions,
Joliet Extensions(Microsoft's contribution for LFN Support), CD-I
extensions using Mode-2 XA format. All these extensions are given in
the later colour books.
These extensions allow you to create bootable CDs, but the base
filesystem is still ISO9660 with 2048KB block size - which I said is
incompatible with a computer filesystem. Hence to retain all the
characteristics of the original CD, you need to dump it either with dd
on *NIX or some such util on Windows.
Most CD-Writing softwares can create such images. but each one has got
special format of its own. The safest bet is ISO9660 which is supported
by almost all the CD-Writing softwares.
BTW, ISO9660 filesystem is very rigid.
After the introduction of ReWritable CDs, there was a need for a
filesystem which could be modified on the fly. This is not allowed by
ISO9660. Hence, there was another varient developed for RW discs called
as UDF or Universal Disc Format. UDF allows writing CDs on the fly by
drag-n-drop mechanism on Windows. It needs special mounting software
though. This method of writing CDs is called Packet Writing.
I still haven't found any such software for Linux as yet.
--
Kunal Gangakhedkar
---------------------------
MCA Student @ VJTI
[EMAIL PROTECTED]
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---------------------------
Office Automation:
The use of computers to improve efficiency in the office
by removing anyone you would want to talk with over coffee.
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