View Full Version : Question about CR-RW's

15-08-2004, 12:49 PM
When I write something to a re-writable, erase it, then write something new to it. Will I still be able to write the full 700mb or whatever amount of original space was on the CD, to it? Or will there be permanent bits and pieces of the old data on the CD?

15-08-2004, 12:58 PM
you will get back the full 700Mb.

15-08-2004, 01:01 PM
Depends how you do it?

My understanding is:

CD-RW are ReWritable by design, which means once full they can be erased and re-written.
Used in that sense, then when "erasing" content and re-writing it, the original data remains and the new data is mapped to the file name, leaving permanent bits of the old file but without direct access to them.

If you use Packet Writing technology (InCD or DirectCD) then I believe the CD-RW behaves more like a floppy disk, and data is rewritten (where possible) over the old.

Either way, its not the most reliable form of storage, as the error rate of a CD-RW is very high compared to a hard drive, and one risks losing all the data as tables of content are updated.

However I stand to be corrected on the above interpretation?

15-08-2004, 01:03 PM
Re-reading the original question, if its a complete erasure and not just the erasure of 1 file, it will regain the full space as suggested.

Graham L
15-08-2004, 02:53 PM
I suspect packet mode actually writes in the unused area, then writes a new table of contents, then overwrites the previous TOC, thereby making it unreadable.

A CD is still a long track, not a lot of cylinders. It can't use "fragments" like a hard disk.

I'd expect a loss of capacity over time, with the full recovery achieved when the whole disk is erased.

Of course I might be wrong.:D I use "blank=fast" in cdrecord (Linux) which does "less than" a full erase, but makes a CD "empty" for reuse.