Encrypted DVDs beyond 2GB

[Pawel Jakub Dawidek]

On Fri, Feb 04, 2005 at 05:43:18PM +0000, RW wrote:
+> Some time ago I asked about creating encrypted data CDs, and someone suggested 
+> using mdconfig to create a file backed md device, encrypted with gdbe, and 
+> then burning the backing file to CD. 
+> 
+> That all works fine, but when the same technique is tried on DVDs, you run 
+> into the problem that FreeBSD 5.3 can't handle a file bigger that 2GB on an 
+> iso9660 filesystem. If you install the development version of mkisofs, it is 
+> possible to burn a DVD containing a file of up to 4GB. Windows 98 can read 
+> the file off the disk, but FreeBSD can't do anything with it.
+> 
+> Using 2 files and having the data mounted at two separate points would be a 
+> bit clumsy. Does anyone have  a better idea?

I'm just doing it now, so few random advices.

- With DVD+RW you don't need iso9660 file system.
  What you need to do is to format it:

	# dvd+rw-format /dev/cd0
	# cdcontrol eject
	# cdcontrol close

  create even UFS2 on it:

	# newfs -U /dev/acd0t01

  mount it and just copy files there.

- GBDE is very, very slow on DVDs for me. Practicaly unusable.
  I wrote a GEOM class for simple encryption which don't have to read
  key sectors, data sectors, etc. So there is no performance difference
  for me.

- If you want to use many md(4) file-backed devices, you can use gconcat(8).
  If you create concatenated device with 'create' subcommand, no on-disk
  metadata is used, so it work like one big file.

- You can try growfs(8) from sysutils/dvd+rw-tools.

-- 
Pawel Jakub Dawidek                       http://www.wheel.pl
pjd at FreeBSD.org                           http://www.FreeBSD.org
FreeBSD committer                         Am I Evil? Yes, I Am!
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