DVD-RW & Multisession - for backups

Good Morning,

I have a DVD-RW disc that was used in Nero 6 with the “multisession” box checked.

When attempting to erase the disc Nero indicates it was erased, however; looking at “–discinfo” still shows a VMS Session.

When attempting to burn to that disc, it indicates the disc is too full to burn what I am asking (only 3,500MB) due to only 1,150MB remaining.


  1. What is the purpose of “multisession” on a DVD-RW and should it be used?
  2. Why can I not actually erase/format this disc (used Nero, nerocmd, or Command Burner).

Thank you for your time and help.

  • Adam

Most advice is to avoid using multisession on DVDs, except for +RW.

If you haven’t used a ‘full’ format, rather than a ‘quick one’, then try that.

Thank you for the information. I will be working with a new disc this afternoon, however; with the current one I have tried all types of formats - full, entire, format, quick, etc.

Yet, that session just hangs in there. What am I missing?

Take imkidd57’s advice and avoid multissession, I’d say even for +RW…
Until not so long ago the specs of -RW had an implicit requirement - you had to “clean” the discs before writing to it again.
If you want to drop files to disc in different times and your drive supports it, its better you give DVD-RAM a chance.

What is the difference between using DVD-RW in a rewriteable sense, and using DVD-RAM? How does DVD-RAM work?

RAM stands for Random Access Memory and basically that’s what DVD-RAM does, you can randomly access it for both reading and writing, whereas RW writes data in one long track (like the groove on an LP). Thanks to this structure your DVD-RAM can act like a Hard Disk, you can copy or delete files using your favorite file browser. DVD-RAM is much more reliable than DVD-RW, but it’s also a little sensitive, and requires cautious handling. Another con is that its relatively slow. I started using it recently for everyday backup, because of its flexibility. Older version of the same file can be overwritten with newer one, files I don’t need any more can be deleted without ereasing the whole media, and I don’t have to use special software like Nero to write on it. I’d definitely recommend DVD-RAM as the best solution for everyday backup, but only for your most important smaller files like documents, projects, pictures… If you have bigger chunks of data that need to be archived, then you’re going to find DVD-RAM too slow for the job and also a little expensive if you have to buy many of them. In that case you shoud use DVD-/+R or find a good DVD+RW. I use Verbatim DVD+RW 4x and I’ve had no problem using them in multisession mode so far.

intx is right about speed, but you have also to consider that RAM has a reliable verification of data integrity and can work in the background without big ressources allocation, therefore you can continue other jobs or to leave it to a particular time to perform the tasks.
Also, due to the specs referred by intx you can perform a kind backup that doesn’t need to write it all every time.

Ok, I understand. Which, of course, leads to more questions:

  1. Do I need to specially format the RW to accept RAM format? If so, how?
  2. Understand the “burn a single groove” however; it sounds like using an RW in which you can overwrite older/changed files is the same as RAM except it requires reading/writing the entire “groove.”
  3. intx mentions “multisession” mode - are you using that “mode” for any particular reason?
  4. Correct me if I am wrong, but multisession mode implies multiple tracks (grooves)?
  5. Still cannot remove that one session from the RW nor can I write to it due to it thinking the disc is basically full.

Thanks for your help.

DVD-RAM is a format by itself, so nothing to do with -r(w) or +r(W).
You can find 2 kind of discs: cartridge or bare. The first works inside a plastic cartridge and requires a drive that can acept it, like some Panasonic. Disc is protected as you don’t touch it for use and dust gets out. Bare comes as the other DVDs in a jewel box.
Sizes you can get normal 4.7GB and double side 9.4GB
Speeds 2x 3x 5x and the new 12x (Maxel said would not sell the 12x in Europe)
You can format them as FAT32 and use as a HDD (the system sees it that way and no need for software as XP supports it native - dif for other windows so/S)
You can also use it as UDF file system and here you have the choice of specific drivers (most well known from Panasonic) or Packet writing software (as InCD).
You find dif prices (higher than write once DVDs) - cheapest I found - 3x Primedisc - € 1,40 in Frankfurt).

But don’t forget to check if your DVD drive has DVD-RAM support.

And to try and answer your original question, if Nero can’t format that DVD-RW then chances are that something has permanently gone wrong with that disc. You should just get rid of it and don’t use the multisession option in the future. Multisession would allow to record on the disc in several sessions if there’s still empty space left after you first session, but apparently DVD discs are mostly designed for single session use, even though Nero tried to implement this option.

Ok. I will look into the DVD-RAM option.

In the meantime, I have placed a blank +RW disc in the drive, and would like to launch the following from “nerocmd”

–error_log c:\burnparams\ErrorLog.txt
–drivename e
–real --tao
–iso dailybackup “file1” “file2” etc…
–media_type media_dvd_m_rw


  1. Do you see any problem with the above parameter list?
  2. Should I use TAO or DAO or does it matter?