Why don't I need to format and partition a CD or DVD before writing files to it?

Question

Every time that I need to use a Flash USB drive, SD card or a HDD I must format it and create a partition before using it, such as NTFS, FAT, FAT32, etc. So this makes me raise some doubts:

1. Why don't I need to do the same with CDs and DVDs?

2. Operating systems usually do it before burning media without warning me?

3. What is the file system typically used on CDs and DVDs?

4. Could I create two or more partitions inside the same DVD?

Answer 1

1. "Formatting" is done when you burn the disc. Because the disc is write only (or being rewritten, in the event of a rewrite), the formatting takes place during the LEAD-IN phase as the TOC or Table of Contents. This TOC is completely dependent upon the data you are burning and therefor cannot be done prior to the burn.

2. Most programs will display "Lead In" or "Burning TOC".

3. UDF

4. You can burn mixed mode CDs that include a data portion and an audio portion. However, I believe all of the information for the entire disc is still stored in one TOC.

Answer 2

The partitioning is done by the burning application. Assuming you are using Windows, because of the NTFS and FAT references, you can use IMGBURN to actually see those processes.

I suggest you to read CDR FAQ and DVDR FAQ, for more information on these mediums.

Answer 3

They are indeed being formated using UDF.

Answer 4

Question #4

Yes but would require software to do this.

Here is one example software