1. After writing a few small files on a DTD, the disc is unreadable on some readers

2. What does “multisession“ mean?

3. Why can you write on DTD only on certain writers?

4. After writing on DTD, why some writers identify well the disc as DVD+R and some as DVD+RW?

5. Is it possible that the time for reading of the DTD disc takes longer than with standard disc?

1. After writing a few small files on a DTD, the disc is unreadable on some readers

DTD - an optical disc based on DVD+R format – while using multisession recording, it has a limited readability if each session is smaller than 1GB.
In case the written data has less than 1GB and the disc stays open for other sessions, some writers will not read the disc or identify it as empty.
This phenomenon is reserved only for DVD format, CD-R does not show such difficulties.
The most advisable for DTD usage is to write it as a whole and lock in the data/close the disc. Doing so you will not face any readability problems.

2. What does “multisession“ mean?

Multisession indicates all optical media (CD/DVD etc..) on which you can add, erase or rewrite data.
It is used mainly for backup of data. Each part (session) starts and ends in so called Lead-in and Lead-out area which takes a certain part of the discs capacity.
Therefore the number of sessions is limited to the capacity of the media. Some older writers may face problems to read multisession media since they do not see all sessions.

3. Why can you write on DTD only on certain writers?

Writing data onto permanent, metal-ceramic layers needs higher laser energy as opposed to standard media.
Unfortunatelly not all writers provide necessary laser power.
The main limitation has been tested with SLIM writers both external as well as USB and in some notebook burners.

4. After writing on DTD, why some writers identify well the disc as DVD+R and some as DVD+RW?

DTD has a DVD+R format however some writers thank to lower reflectivity do interpret the disc as a DVD+RW.

5. Is it possible that the time for reading of the DTD disc takes longer than with standard disc?

Yes, this is due to lower reflectivity than the standard DVD + R.