Re: dvd+rw-tools-5.20.4.10.8: File is too large

[scdbackup@gmx.net]

David Wilson >
> mkisofs: Value too large for defined data type. File
> /tmp/backup-04082004.tar.gz is too large - ignoring
> root@server:/tmp# ls -l /tmp/backup-04082004.tar.gz
> -rw-r--r--    1 root     root     2930771449 Aug  4 11:06
> /tmp/backup-04082004.tar.gz
 
In general, this restriction is quite wise, since reading of a
file >= 2GB from ISO file systems is known to fail on many
existing systems.

Andy Polyakov states in http://lists.debian.org/cdwrite/2004/03/msg00158.html
"Once again. Keep in mind that Linux isofs implementation is deficient in
such way which effectively limits maximum file size to 2G-1 byte. ...
as it was discussed serveral times on this list."

Joerg Schilling states in File AN-2.01a10 of cdrtools :
"
-       Try to support files >= 2 GB.
        Note that mkisofs is not yet written cleanly so there may be problems
        if files >= are used. In such a case, please report.
"

So you might possibly have more success with the current
cdrtools alpha version. That does not solve any reader
software problems, though.


Helmut Jarausch >
> I think there is a kernel patch to be in 2.6.8 which removes this.

If this provides remedy for the Linux isofs limitations mentioned
by Andy then this would be a very desirable thing.


A different approach suitable even for quite old reader systems :

If the DVDs are intended for use on systems only, where it is
easy to read them as raw data stream (e.g. via /dev/dvd) then
one may consider to write the tar file without an ISO wrap. 
Like :

  growisofs -use-the-force-luke -dvd-compat -speed=any \
             -Z /dev/scd0=/tmp/backup-04082004.tar.gz

The DVD would then be readable like a tar formatted tape :

  tar tvzf /dev/scd0

Not to be mounted as file system, of course. 

I regularly use pipelines like this :

  afio ... | growisofs ... -Z /dev/scd0=/proc/self/fd/0


If you need to have the DVD mountable, there is the project shunt
which addresses the issue of large tar backups wrapped in ISO format : 
  http://www.serice.net/shunt/

The site also contains a statement about a kernel patch and 2.6.8.
This one does not seem to exactly address 2GB file size problems but
rather a problem with inodes located beyond 4GB. (It does not appear with
single session mkisofs, as Paul Serice, the author of shunt, told me.)

So i am not sure about the status of large files on ISO file systems
with kernel 2.6.


Have a nice day :)

Thomas