Re: DVDs created with too large files
>From: Gary Houston <ghouston@arglist.com>
>I have been using dvd+rw-tools (5.13.4.7.4) and mkisofs (cdrtools 1.11a29)
>to write backups to DVD. This generally works. However I encountered
>a problem when one of the files was 2351679431 bytes in size: the disk
>was written with no errors reported, but on testing proved to be unreadable
>to linux 2.4.21. On mounting the disk a warning was reported:
>Warning: defective CD-ROM. Enabling "cruft" mount option.
>The large file now appeared to be only 2869191 bytes and is truncated
>on reading.
>Examining the Linux sources shows the following comment in fs/isofs/inode.c:
> /*
> * The ISO-9660 filesystem only stores 32 bits for file size.
> * mkisofs handles files up to 2GB-2 = 2147483646 = 0x7FFFFFFE bytes
> * in size. This is according to the large file summit paper from 1996.
> * WARNING: ISO-9660 filesystems > 1 GB and even > 2 GB are fully
> * legal. Do not prevent to use DVD's schilling@fokus.gmd.de
> */
> if ((inode->i_size < 0 || inode->i_size > 0x7FFFFFFE) &&
> inode->i_sb->u.isofs_sb.s_cruft == 'n') {
> printk(KERN_WARNING "Warning: defective CD-ROM. "
> "Enabling \"cruft\" mount option.\n");
> inode->i_sb->u.isofs_sb.s_cruft = 'y';
> }
The hacky change is from me, but note:
- As the source before did not support files > 512 MB, nobody could
have tested multi extent files!
- If I would have removed the "limitation" completely, it would most
likely not have been accepted as a patch :-(
Jörg
--
EMail:joerg@schily.isdn.cs.tu-berlin.de (home) Jörg Schilling D-13353 Berlin
js@cs.tu-berlin.de (uni) If you don't have iso-8859-1
schilling@fokus.fraunhofer.de (work) chars I am J"org Schilling
URL: http://www.fokus.fraunhofer.de/usr/schilling ftp://ftp.berlios.de/pub/schily
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