Why would a valid DVD show zero files on Linux?

Why would a valid DVD show zero files on Linux?

[Bryce Nesbitt]

I have a DVD ROM (It's DeLorme Topo USA), which works fine booted in Windows.
Under Linux it mounts fine, but shows no files.  Everything looks normal, like
it should just work.

What's up?  And ideas?


[root@HardHat bryce]# df
...
/dev/scd0               326028    326028         0 100% /mnt/cdrom
/dev/hdc               3277426   3277426         0 100% /mnt/dvdrom

[root@HardHat bryce]# uname -a
Linux HardHat 2.4.2-2 #1 Sun Apr 8 20:41:30 EDT 2001 i686 unknown


[root@HardHat bryce]# cat /proc/filesystems 
nodev   sockfs
nodev   tmpfs
nodev   shm
nodev   pipefs
nodev   proc
        ext2
        iso9660
nodev   devpts
nodev   usbdevfs
        vfat
nodev   autofs

[root@HardHat bryce]# dd if=/dev/hdc of=/tmp/A bs=1024 count=200
200+0 records in
200+0 records out
[root@HardHat bryce]# strings /tmp/A
CD001
                                T3DVD                           
                                                                                                                                DELORME                                                                                                                         ADJ                                                                                                                                                                                                                                                                                                                                                                            1999111712541000
2001022814540400
2001022814540400
CD001
9%/E
1999111712541000
2001022814540400
2001022814540400
CD001
BEA01
NSR02
TEA01
T3DVD
00026f70 MTC ForDVD 5.9, March 2000
OSTA Compressed Unicode
OSTA Compressed Unicode
*Multimedia Tech. Cntr.
*UDF LV Info

Why would a valid DVD show zero files on Linux?

[Bryce Nesbitt]

I have a DVD ROM (It's DeLorme Topo USA), which works fine booted in Windows.
Under Linux it mounts fine, but shows no files.  Everything looks normal, like
it should just work.

What's up?  And ideas?


[root@HardHat bryce]# df
...
/dev/scd0               326028    326028         0 100% /mnt/cdrom
/dev/hdc               3277426   3277426         0 100% /mnt/dvdrom

[root@HardHat bryce]# uname -a
Linux HardHat 2.4.2-2 #1 Sun Apr 8 20:41:30 EDT 2001 i686 unknown


[root@HardHat bryce]# cat /proc/filesystems 
nodev   sockfs
nodev   tmpfs
nodev   shm
nodev   pipefs
nodev   proc
        ext2
        iso9660
nodev   devpts
nodev   usbdevfs
        vfat
nodev   autofs

[root@HardHat bryce]# dd if=/dev/hdc of=/tmp/A bs=1024 count=200
200+0 records in
200+0 records out
[root@HardHat bryce]# strings /tmp/A
CD001
                                T3DVD                           
                                                                                                                                DELORME                                                                                                                         ADJ                                                                                                                                                                                                                                                                                                                                                                            1999111712541000
2001022814540400
2001022814540400
CD001
9%/E
1999111712541000
2001022814540400
2001022814540400
CD001
BEA01
NSR02
TEA01
T3DVD
00026f70 MTC ForDVD 5.9, March 2000
OSTA Compressed Unicode
OSTA Compressed Unicode
*Multimedia Tech. Cntr.
*UDF LV Info



# grep ATAPI /var/log/messages
Dec 30 17:53:40 hardhat kernel: hdc: \x03 DVD-ROM SD-M1402, ATAPI CD/DVD-ROM 
drive

Re: Why would a valid DVD show zero files on Linux?

[Alan Cox]

> I have a DVD ROM (It's DeLorme Topo USA), which works fine booted in Windows.
> Under Linux it mounts fine, but shows no files.  Everything looks normal, like
> it should just work.

Mount it as a DVD not a CD-ROM media (ie udf format not iso9660) at a guess

Re: Why would a valid DVD show zero files on Linux?

[Bryce Nesbitt]

Lionel Bouton wrote:
> 
> Bryce Nesbitt wrote:
> 
> > I have a DVD ROM (It's DeLorme Topo USA), which works fine booted in Windows.
> > Under Linux it mounts fine, but shows no files.  Everything looks normal, like
> > it should just work.
> >
> > What's up?  And ideas?
> 
> Try udf fs. I don't know the details but I guess a dvd with empty
> iso9660 meta-data but with correct udf meta-data could show these symptoms.

That does it!

Works:
	mount -t udf /dev/hdc /mnt/dvdrom/

Shows no complaints, no log entries, and no files:
	mount -t iso9660 /dev/hdc /mnt/dvdrom/
	mount /dev/hdc /mnt/dvdrom/
	
Does anyone want the first few K of this DVD to see why the autodetection
is not working better?  Do you want me to upgrade past Kernel 2.4.2-2 first?
Is RedHat 7.2's kernel good enough?

Thanks!

		-Bryce

Re: Why would a valid DVD show zero files on Linux?

[RaúlNúñez de Arenas Coronado]

[-- Warning: decoded text below may be mangled, UTF-8 assumed --]
[-- Attachment #1: Type: text/plain, Size: 123 bytes --]

    Hello Bryce :)

>What's up?  And ideas?

    Have you 'UDF' support in your kernel? This may be the problem.

    Raúl

Re: Why would a valid DVD show zero files on Linux?

[Alan Cox]

> Does anyone want the first few K of this DVD to see why the autodetection
> is not working better?  Do you want me to upgrade past Kernel 2.4.2-2 first?
> Is RedHat 7.2's kernel good enough?

The autodetection is working. Your DVD has a UDF file system on it and a
blank iso9660 one.

Re: Why would a valid DVD show zero files on Linux?

[Bryce Nesbitt]

Alan Cox wrote:
> 
> > Does anyone want the first few K of this DVD to see why the autodetection
> > is not working better?  Do you want me to upgrade past Kernel 2.4.2-2 first?
> > Is RedHat 7.2's kernel good enough?
> 
> The autodetection is working. Your DVD has a UDF file system on it and a
> blank iso9660 one.

Understood.   However, why can't that combination "just work"?  Changing
/etc/fstab every time I switch between sticking in a CD-ROM and DVD-ROM is not cool.
Certainly that "other operating system" does not make me do that.

A disk with a blank iso9660 plus a full UDF ought to automatically mount UDF, no?
How hard would that be to detect?

		-Bryce


PS: I manually mount anyway, and only have two DVD-ROMs, so it's not such a
big deal for me.  But as DVD rom becomes more popular it could get inconvienent.

Re: Why would a valid DVD show zero files on Linux?

[Marius Gedminas]

On Mon, Dec 31, 2001 at 09:21:24AM -0500, Bryce Nesbitt wrote:
> > The autodetection is working. Your DVD has a UDF file system on it and a
> > blank iso9660 one.
> 
> Understood.   However, why can't that combination "just work"?  Changing
> /etc/fstab every time I switch between sticking in a CD-ROM and DVD-ROM is not cool.
> Certainly that "other operating system" does not make me do that.

I used to have two lines in my /etc/fstab: one to mount /dev/cdrom on
/cdrom as iso9660, another to mount /dev/cdrom on /cdudf as udf.  Then
it's simply a matter of mount /cdrom or mount /cdudf.

Of course, that "other operating system" does not require you to
manually mount CD-ROMs at all.

Marius Gedminas
-- 
Thus spake the master programmer:
        "After three days without programming, life becomes meaningless."
                -- Geoffrey James, "The Tao of Programming"

Re: Why would a valid DVD show zero files on Linux?

[Vitaly Lipatov]

On 31 December 2001 17:21, Bryce Nesbitt wrote:
> A disk with a blank iso9660 plus a full UDF ought to automatically mount
> UDF, no? How hard would that be to detect?
You have to set type 'auto' in fstab and add 'udf' in first line of 
/etc/filesystems.

Follow is piece of man mount:
              The type iso9660 is the default.  If no  -t  option
              is  given,  or  if  the auto type is specified, the
              superblock  is  probed  for  the  filesystem   type
              (minix, ext, ext2, ext3, xiafs, iso9660, jfs, reis-
              erfs, romfs, ufs, ntfs,  qnx4,  bfs,  xfs,  cramfs,
              hfs,  hpfs,  adfs,  vxfs  are  supported).  If this
              probe fails,  mount  will  try  to  read  the  file
              /etc/filesystems,  or,  if  that  does  not  exist,
              /proc/filesystems.  All  of  the  filesystem  types
              listed  there  will be tried, except for those that
              are labeled "nodev" (e.g., devpts, proc and nfs).

Please tell me is you successfully done it.
On my system it do not work. :(
-- 
Lav
Vitaly Lipatov
GNU! Linux! LaTeX! LyX!

Re: Why would a valid DVD show zero files on Linux?

[Andries.Brouwer]

Vitaly Lipatov:

> On my system it do not work. :(

So, if either mount is broken or its documentation
is outdated, why not write to the maintainer (aeb@cwi.nl)
and tell what is wrong? Empty complaints are useless.

Andries

Re: Why would a valid DVD show zero files on Linux?

[Cameron Simpson]

On Mon, Dec 31, 2001 at 09:21:24AM -0500, Bryce Nesbitt <bryce@obviously.com> wrote:
| Alan Cox wrote:
| > The autodetection is working. Your DVD has a UDF file system on it and a
| > blank iso9660 one.
| Understood.   However, why can't that combination "just work"?  Changing
| /etc/fstab every time I switch between sticking in a CD-ROM and DVD-ROM is not cool.
| Certainly that "other operating system" does not make me do that.

I do this via autofs, and just say /mnt/dvd when I want UDF and /mnt/cdrom
when I want a CDROM. It does depend on having my eyes open when I stick
the medium in the drive...

Of course, this merely bypasses the autodetection.
-- 
Cameron Simpson, DoD#743        cs@zip.com.au    http://www.zip.com.au/~cs/

Ed Campbell's <ed@Tekelex.Com> pointers for long trips:
7. Be prepared to have at least 1 flat, 2 electrical problems and a
   broken chain. Maybe a broken clutch cable too. The best prevention
   is to be able to fix it on the spot, only things you can't fix
   will break according to the law.

Re: Why would a valid DVD show zero files on Linux?

[Bryce Nesbitt]

Cameron Simpson wrote:
> 
> On Mon, Dec 31, 2001 at 09:21:24AM -0500, Bryce Nesbitt <bryce@obviously.com> wrote:
> | Alan Cox wrote:
> | > The autodetection is working. Your DVD has a UDF file system on it and a
> | > blank iso9660 one.
> | Understood.   However, why can't that combination "just work"?  Changing
> | /etc/fstab every time I switch between sticking in a CD-ROM and DVD-ROM is not cool.
> | Certainly that "other operating system" does not make me do that.
> 
> I do this via autofs, and just say /mnt/dvd when I want UDF and /mnt/cdrom
> when I want a CDROM. It does depend on having my eyes open when I stick
> the medium in the drive...
> 
> Of course, this merely bypasses the autodetection.

Ok, I admit, I do the same thing.  I manually mount.  But let's get in
the head of a user, why should they care what type of 5 inch round shiny
thing they just inserted?

Are there any cases where udf filesystems are present on cdrom's that should
be read as iso9660?  Someone mentioned it's a hard heuristic to figure out
which fake filename the empty iso9660 filesystem uses.  How about, instead,
pick the larger of the two filesystems if both are present.

			-Bryce

Re: Why would a valid DVD show zero files on Linux?

[Alan Cox]

> Are there any cases where udf filesystems are present on cdrom's that should
> be read as iso9660?  Someone mentioned it's a hard heuristic to figure out
> which fake filename the empty iso9660 filesystem uses.  How about, instead,
> pick the larger of the two filesystems if both are present.

Now you've made the behaviour effectively random which is even worse. On
a standard DVD the two file systems are the same. Some copy protected CD's
have a UDF file system on them that isnt interesting. Some DVD's have an
ISO fs that isnt interesting.

Re: Why would a valid DVD show zero files on Linux?

[Ryan Cumming]

On January 1, 2002 02:12, Alan Cox wrote:
> Now you've made the behaviour effectively random which is even worse. On
> a standard DVD the two file systems are the same. Some copy protected CD's
> have a UDF file system on them that isnt interesting. Some DVD's have an
> ISO fs that isnt interesting.

It seems like it should be up to userspace to first try UDF for DVDs, and 
first try iso9660 for CDs.

-Ryan

Re: Why would a valid DVD show zero files on Linux?

[Alan Cox]

> Of course, that "other operating system" does not require you to
> manually mount CD-ROMs at all.

Nor does Linux if you set it up right. Its a case of making proper use of
existing interfaces and a bit of userspace magic. And all done without the
student fun of leaving "format/u c:" autostart cd-r's around labelled "porn"

Re: Why would a valid DVD show zero files on Linux?

[Alan Cox]

> > have a UDF file system on them that isnt interesting. Some DVD's have an
> > ISO fs that isnt interesting.
> 
> It seems like it should be up to userspace to first try UDF for DVDs, and 
> first try iso9660 for CDs.

Guess what. You can tell user space to do that

Re: Why would a valid DVD show zero files on Linux?

[Alan Cox]

> Understood.   However, why can't that combination "just work"?  Changing
> /etc/fstab every time I switch between sticking in a CD-ROM and DVD-ROM is not cool.
> Certainly that "other operating system" does not make me do that.

man fstab
man ln

Its not a hard problem to solve that one

Re: Why would a valid DVD show zero files on Linux?

[Kai Henningsen]

Andries.Brouwer@cwi.nl  wrote on 31.12.01 in <UTC200112311529.PAA122887.aeb@cwi.nl>:

> Vitaly Lipatov:
>
> > On my system it do not work. :(
>
> So, if either mount is broken or its documentation
> is outdated, why not write to the maintainer (aeb@cwi.nl)
> and tell what is wrong? Empty complaints are useless.

Well, it seems to me that the behaviour described matches the description:  
the list mount claims to try *first*, before looking at user-supplied  
filesystem lists, includes iso9660 but not UDF. So ...

MfG Kai

Re: Why would a valid DVD show zero files on Linux?

[Bryce Nesbitt]

Alan Cox wrote:
> 
> > Understood.   However, why can't that combination "just work"?  Changing
> > ... every time I switch between sticking in a CD-ROM and DVD-ROM is not cool.
> > Certainly that "other operating system" does not make me do that.
> 
> man fstab
> man ln
> 
> Its not a hard problem to solve that one

My vision of Linux extends to people who don't have the ability, desire or
time to "man fstab" *.


> > Are there any cases where udf filesystems are present on cdrom's that should
> > be read as iso9660?  Someone mentioned it's a hard heuristic to figure out
> > which fake filename the empty iso9660 filesystem uses.  How about, instead,
> > pick the larger of the two filesystems if both are present.
> 
> Now you've made the behaviour effectively random which is even worse. On
> a standard DVD the two file systems are the same. Some copy protected CD's
> have a UDF file system on them that isnt interesting. Some DVD's have an
> ISO fs that isnt interesting.

Windows, somehow, detects the difference.  Whatever method used by Windows
will be the one tested by the makers of most DVD/CDROM's.

Right now the behavior is deterministic from the Kernel's point of view,
but random from the users point of view (e.g. "the last 5 DVD-ROM's I bought
just worked, this one does not work").  Can detection be automated?  How
does Windows do it?  Can Linux do it even better?


If the distinction is something that can be automated well, then what is
the argument against doing it?

			-Bryce


* I fit under "desire".  Once I learned that udf existed (it's not in 
"man fstab"), I knew what to do.  I'd rather not know or care :-)!

Re: Why would a valid DVD show zero files on Linux?

[Alan Cox]

> Windows, somehow, detects the difference.  Whatever method used by Windows
> will be the one tested by the makers of most DVD/CDROM's.

Actually half of the copy protected CD thing relies on the fact windows does
not get its decisions right.

> If the distinction is something that can be automated well, then what is
> the argument against doing it?

Certainly relevant - but for the kde file manager and gnome nautilus lists

Re: Why would a valid DVD show zero files on Linux?

[Grahame Jordan]

All,

Is this similar to the VCD problem I have where I can mount the cd and
read the smaller files but cannot read the mpg file (avseq01.dat)?

I installed mtv which plays the CD OK.  But this does not solve the real
problem.

I to believe that the user should not need to know the technical
intricaties of how to mount it (iso9660 udf XA) etc. It should just
work.

The question is where to fix it?  If it is possible to do in the kernel
it should be done there.  If it nees to be done in userspace then where
in userspace does this need to be fixed?  I am willing to help but know
not where to start.

Thanks

Grahame Jordan


On Wed, 2002-01-02 at 02:24, Alan Cox wrote:
> > Windows, somehow, detects the difference.  Whatever method used by Windows
> > will be the one tested by the makers of most DVD/CDROM's.
> 
> Actually half of the copy protected CD thing relies on the fact windows does
> not get its decisions right.
> 
> > If the distinction is something that can be automated well, then what is
> > the argument against doing it?
> 
> Certainly relevant - but for the kde file manager and gnome nautilus lists
> -
> To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
> the body of a message to majordomo@vger.kernel.org
> More majordomo info at  http://vger.kernel.org/majordomo-info.html
> Please read the FAQ at  http://www.tux.org/lkml/
-- 
Grahame Jordan
TheForce

Re: Why would a valid DVD show zero files on Linux?

[Bryce Nesbitt]

As I'm learning, this is complex.  Some DVD's, Alan says, have differing
udf and iso9660 filesystems for copy protection reasons.  They spoof windows
into not allowing easy access to some files.  Maybe your VCD issue is similar.

Try mounting the disc both ways (udf and iso9660) and compare the filesystems.

I'm told windows prefers udf to iso9660.  Linux does it the other way 'round.
Thus a disc that works perfectly on Windows shows zero files on Linux
(confusing users and sysadmins alike, since prior to today, the man pages
for mount and fstab were silent on the issue).

			-Bryce

PS: Thanks for being the first person to also think users should not have
to know about the udf vs. iso9660 issue.

It looks like util-linux, mount is the place to fix this:
ftp://ftp.win.tue.nl/pub/home/aeb/linux-local/utils/util-linux/

See also http://www.osta.org/ , the Optical Storage Technology Association.


Grahame Jordan wrote:
> 
> All,
> 
> Is this similar to the VCD problem I have where I can mount the cd and
> read the smaller files but cannot read the mpg file (avseq01.dat)?
> 
> I installed mtv which plays the CD OK.  But this does not solve the real
> problem.
> 
> I to believe that the user should not need to know the technical
> intricaties of how to mount it (iso9660 udf XA) etc. It should just
> work.
> 
> The question is where to fix it?  If it is possible to do in the kernel
> it should be done there.  If it nees to be done in userspace then where
> in userspace does this need to be fixed?  I am willing to help but know
> not where to start.
> 
> Thanks
> 
> Grahame Jordan
> 
> On Wed, 2002-01-02 at 02:24, Alan Cox wrote:
> > > Windows, somehow, detects the difference.  Whatever method used by Windows
> > > will be the one tested by the makers of most DVD/CDROM's.
> >
> > Actually half of the copy protected CD thing relies on the fact windows does
> > not get its decisions right.
> >
> > > If the distinction is something that can be automated well, then what is
> > > the argument against doing it?
> >
> > Certainly relevant - but for the kde file manager and gnome nautilus lists
> > -
> > To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
> > the body of a message to majordomo@vger.kernel.org
> > More majordomo info at  http://vger.kernel.org/majordomo-info.html
> > Please read the FAQ at  http://www.tux.org/lkml/
> --
> Grahame Jordan
> TheForce

-- 
Hi! I'm a do-it-yourself virus... please delete 4 files at random
from your hard drive.  Pass me on to all your friends.

Re: Why would a valid DVD show zero files on Linux?

[Alan Cox]

> Is this similar to the VCD problem I have where I can mount the cd and
> read the smaller files but cannot read the mpg file (avseq01.dat)?

Unrelated. The .dat files are not normal ISO9660 files they are indexes into
the VCD data which is physical layer stuff and sorted into tracks audio
style.

> it should be done there.  If it nees to be done in userspace then where
> in userspace does this need to be fixed?  I am willing to help but know
> not where to start.

Xine seems to play my videocd's nicely.

Alan

Re: Why would a valid DVD show zero files on Linux?

[Grahame Jordan]

We should be able to use cp or read it though.

I will look into util-linux.

Thanks

Grahame Jordan


On Wed, 2002-01-02 at 10:53, Alan Cox wrote:
> > Is this similar to the VCD problem I have where I can mount the cd and
> > read the smaller files but cannot read the mpg file (avseq01.dat)?
> 
> Unrelated. The .dat files are not normal ISO9660 files they are indexes into
> the VCD data which is physical layer stuff and sorted into tracks audio
> style.
> 
> > it should be done there.  If it nees to be done in userspace then where
> > in userspace does this need to be fixed?  I am willing to help but know
> > not where to start.
> 
> Xine seems to play my videocd's nicely.
> 
> Alan
-- 
Grahame Jordan
TheForce

Re: Why would a valid DVD show zero files on Linux?

[Andries.Brouwer]

> Here are the first 2048 1024 byte blocks.

Hmm. I am a bit slow, but just looked at this image.
It looks fine in iso9660 style, provided you give the
nojoliet option. I get:

# mount DeLorme_TopoUSA_DVD.head /mnt -t iso9660 -o loop,nojoliet
# ls -l /mnt
total 12
dr-xr-xr-x    1 root     root         2048 Feb 28  2001 .
drwxr-xr-x   31 root     root         4096 Jan  3 02:11 ..
-r-xr-xr-x    1 root     root         2763 Feb 28  2001 cd.txt
dr-xr-xr-x    1 root     root         2048 Feb 28  2001 data
-r-xr-xr-x    1 root     root          196 Feb 28  2001 pdataset.txt

and

# mount DeLorme_TopoUSA_DVD.head /mnt -t udf -o loop
# ls -l /mnt
total 14
dr-xr-xr-x    3 4294967295 4294967295      184 Feb 28  2001 .
drwxr-xr-x   31 root     root         4096 Jan  3 02:11 ..
-r--r--r--    1 4294967295 4294967295     2763 Feb 28  2001 CD.TXT
dr-xr-xr-x    2 4294967295 4294967295      380 Feb 28  2001 DATA
-r--r--r--    1 4294967295 4294967295      196 Feb 28  2001 PDATASET.TXT

so the iso9660 version looks a bit better than the udf version.
(But I cannot look at the actual contents because the initial
fragment is not large enough. You can check for yourself
whether the nojoliet mount is OK.)

Thus, there do not seem reasons to change mount(2) or mount(8)
in the way you suggested. There is no "empty iso9660 filesystem" here.

Andries

Re: Why would a valid DVD show zero files on Linux?

[Bryce Nesbitt]

Confirmed.  The DVD in question (DeLorme Topo USA) shows files when mounted
with "nojoliet". But when the application is run, the maps are scrambled.
It must be mounted as udf to work.

The original bug report incorrectly asserted that the iso9660 filesystem
was empty, sorry about that.

But this does seem to be an example (which
has been widely reported elsewhere) of a DVD with a differing udf and iso9660
filesystems.  Lots of people have reported that, since Windows no longer
uses the "iso9660 udf bridge", lots of mastered DVDs have unintentionally
corrupt versions of it.  Others have hinted this is done deliberately for
copy protection reasons.

			-Bryce

Solving the problem by documentation
------------------------------------
The patches already supplied to mount(8) and fstab (5) give give a sysadmin
the tools to learn about and solve the problem, thanks for applying them!

It just seems like there's a bit more to say about potentially differing udf
and iso9660 filesytems on the same disc... that's the thiking behind the extra
paragraph in the patch.



Solving the problem automatically (keeping the issue out of the users face)
---------------------------------------------------------------------------
Mastering houses will test their discs on Windows.  While in general emulating Windows
is something I hate, here it makes sense.  The more
closely the mount automounter emulates how windows automounts, the more likely 
this type of discussion will never need to come up. 

According to Alan Windows tries udf first, blindly, then falls back to iso9660.

As many people pointed out, this is not a kernel issue, it's a automount
isuse.


Andries.Brouwer@cwi.nl wrote:
> 
> > Here are the first 2048 1024 byte blocks.
> 
> Hmm. I am a bit slow, but just looked at this image.
> It looks fine in iso9660 style, provided you give the
> nojoliet option. I get:
> 
> # mount DeLorme_TopoUSA_DVD.head /mnt -t iso9660 -o loop,nojoliet
> # ls -l /mnt
> total 12
> dr-xr-xr-x    1 root     root         2048 Feb 28  2001 .
> drwxr-xr-x   31 root     root         4096 Jan  3 02:11 ..
> -r-xr-xr-x    1 root     root         2763 Feb 28  2001 cd.txt
> dr-xr-xr-x    1 root     root         2048 Feb 28  2001 data
> -r-xr-xr-x    1 root     root          196 Feb 28  2001 pdataset.txt
> 
> and
> 
> # mount DeLorme_TopoUSA_DVD.head /mnt -t udf -o loop
> # ls -l /mnt
> total 14
> dr-xr-xr-x    3 4294967295 4294967295      184 Feb 28  2001 .
> drwxr-xr-x   31 root     root         4096 Jan  3 02:11 ..
> -r--r--r--    1 4294967295 4294967295     2763 Feb 28  2001 CD.TXT
> dr-xr-xr-x    2 4294967295 4294967295      380 Feb 28  2001 DATA
> -r--r--r--    1 4294967295 4294967295      196 Feb 28  2001 PDATASET.TXT
> 
> so the iso9660 version looks a bit better than the udf version.
> (But I cannot look at the actual contents because the initial
> fragment is not large enough. You can check for yourself
> whether the nojoliet mount is OK.)
> 
> Thus, there do not seem reasons to change mount(2) or mount(8)
> in the way you suggested. There is no "empty iso9660 filesystem" here.
> 
> Andries

Re: Why would a valid DVD show zero files on Linux?

[Bryce Nesbitt]

Here is the table of contents mounted three ways.  First udf, then
iso9660, then iso9660 nojoliet.  Only the udf version works with the
application.  Note that the huge udf filesizes are not a mistake -
this DVD is also offered as 7 CD set.


/mnt/cdrom1/:
total 14
dr-xr-xr-x    3 4294967295 4294967295      184 Feb 28  2001 .
drwxr-xr-x   24 root     root         4096 Jan  5 10:27 ..
-r--r--r--    1 4294967295 4294967295     2763 Feb 28  2001 CD.TXT
dr-xr-xr-x    2 4294967295 4294967295      380 Feb 28  2001 DATA
-r--r--r--    1 4294967295 4294967295      196 Feb 28  2001 PDATASET.TXT

/mnt/cdrom1/DATA:
total 3266832
dr-xr-xr-x    2 4294967295 4294967295      380 Feb 28  2001 .
dr-xr-xr-x    3 4294967295 4294967295      184 Feb 28  2001 ..
-r--r--r--    1 4294967295 4294967295 34735660 Feb 28  2001 GRIDAK.DAT
-r--r--r--    1 4294967295 4294967295  1921298 Feb 28  2001 GRIDAK.IND
-r--r--r--    1 4294967295 4294967295 1832319997 Feb 28  2001 GRID.DAT
-r--r--r--    1 4294967295 4294967295 51128921 Feb 28  2001 GRID.IND
-r--r--r--    1 4294967295 4294967295    34839 Feb 28  2001 VEC.COV
-r--r--r--    1 4294967295 4294967295 1424439251 Feb 28  2001 VEC.V
-r--r--r--    1 4294967295 4294967295   643405 Feb 28  2001 VEC.VI


/mnt/cdrom1/:
total 1
dr-xr-xr-x    1 root     root            1 Feb 28  2001 .



/mnt/cdrom1/:
total 12
dr-xr-xr-x    1 root     root         2048 Feb 28  2001 .
drwxr-xr-x   24 root     root         4096 Jan  5 10:27 ..
-r-xr-xr-x    1 root     root         2763 Feb 28  2001 cd.txt
dr-xr-xr-x    1 root     root         2048 Feb 28  2001 data
-r-xr-xr-x    1 root     root          196 Feb 28  2001 pdataset.txt

/mnt/cdrom1/data:
total 22849
dr-xr-xr-x    1 root     root         2048 Feb 28  2001 .
dr-xr-xr-x    1 root     root         2048 Feb 28  2001 ..
-r-xr-xr-x    1 root     root      1181228 Feb 28  2001 gridak.dat
-r-xr-xr-x    1 root     root      1921298 Feb 28  2001 gridak.ind
-r-xr-xr-x    1 root     root      3603453 Feb 28  2001 grid.dat
-r-xr-xr-x    1 root     root       797273 Feb 28  2001 grid.ind
-r-xr-xr-x    1 root     root        34839 Feb 28  2001 vec.cov
-r-xr-xr-x    1 root     root     15153107 Feb 28  2001 vec.v
-r-xr-xr-x    1 root     root       643405 Feb 28  2001 vec.vi


As this is one clear example of differing iso9660 and udf views
of the same disc, I propose to change mount(8) and fstab(5) to warn the
two can be different (either intentionally, accidentally, or because
of iso9660 limitations).

I also propose to change "mount -t auto" to try udf first, and fall back to
iso9660.  This, of course, requires more discussion first.  But based
on serching other lists, reading the udf "iso9660 bridge" spec,
and email conversations, it seems to be the right long term answer.
Since udf is used on CD's, I propose that udf be tried first for
all meda, not just DVD's.

The kernel, of course, remains unchanged, and because you're using Linux,
you would still be able force mount anything you want.

			-Bryce



Andries.Brouwer@cwi.nl wrote:
> 
> > Here are the first 2048 1024 byte blocks.
> 
> Hmm. I am a bit slow, but just looked at this image.
> It looks fine in iso9660 style, provided you give the
> nojoliet option. I get:
> 
> # mount DeLorme_TopoUSA_DVD.head /mnt -t iso9660 -o loop,nojoliet
> # ls -l /mnt
> total 12
> dr-xr-xr-x    1 root     root         2048 Feb 28  2001 .
> drwxr-xr-x   31 root     root         4096 Jan  3 02:11 ..
> -r-xr-xr-x    1 root     root         2763 Feb 28  2001 cd.txt
> dr-xr-xr-x    1 root     root         2048 Feb 28  2001 data
> -r-xr-xr-x    1 root     root          196 Feb 28  2001 pdataset.txt
> 
> and
> 
> # mount DeLorme_TopoUSA_DVD.head /mnt -t udf -o loop
> # ls -l /mnt
> total 14
> dr-xr-xr-x    3 4294967295 4294967295      184 Feb 28  2001 .
> drwxr-xr-x   31 root     root         4096 Jan  3 02:11 ..
> -r--r--r--    1 4294967295 4294967295     2763 Feb 28  2001 CD.TXT
> dr-xr-xr-x    2 4294967295 4294967295      380 Feb 28  2001 DATA
> -r--r--r--    1 4294967295 4294967295      196 Feb 28  2001 PDATASET.TXT
> 
> so the iso9660 version looks a bit better than the udf version.
> (But I cannot look at the actual contents because the initial
> fragment is not large enough. You can check for yourself
> whether the nojoliet mount is OK.)
> 
> Thus, there do not seem reasons to change mount(2) or mount(8)
> in the way you suggested. There is no "empty iso9660 filesystem" here.
> 
> Andries

Re: Why would a valid DVD show zero files on Linux?

[Andries.Brouwer]

	From bryce@obviously.com Sat Jan  5 17:14:28 2002

	Here is the table of contents mounted three ways.  First udf, then
	iso9660, then iso9660 nojoliet.  Only the udf version works with the
	application.  Note that the huge udf filesizes are not a mistake -
	this DVD is also offered as 7 CD set.

[iso9660 nojoliet:]

	/mnt/cdrom1/data:
	total 22849
	dr-xr-xr-x    1 root     root         2048 Feb 28  2001 .
	dr-xr-xr-x    1 root     root         2048 Feb 28  2001 ..
	-r-xr-xr-x    1 root     root      1181228 Feb 28  2001 gridak.dat
	-r-xr-xr-x    1 root     root      1921298 Feb 28  2001 gridak.ind
	-r-xr-xr-x    1 root     root      3603453 Feb 28  2001 grid.dat
	-r-xr-xr-x    1 root     root       797273 Feb 28  2001 grid.ind
	-r-xr-xr-x    1 root     root        34839 Feb 28  2001 vec.cov
	-r-xr-xr-x    1 root     root     15153107 Feb 28  2001 vec.v
	-r-xr-xr-x    1 root     root       643405 Feb 28  2001 vec.vi

Hmm. I find

total 3266826
dr-xr-xr-x    1 root     root         2048 Feb 28  2001 .
dr-xr-xr-x    1 root     root         2048 Feb 28  2001 ..
-r-xr-xr-x    1 root     root     1832319997 Feb 28  2001 grid.dat
-r-xr-xr-x    1 root     root     51128921 Feb 28  2001 grid.ind
-r-xr-xr-x    1 root     root     34735660 Feb 28  2001 gridak.dat
-r-xr-xr-x    1 root     root      1921298 Feb 28  2001 gridak.ind
-r-xr-xr-x    1 root     root        34839 Feb 28  2001 vec.cov
-r-xr-xr-x    1 root     root     1424439251 Feb 28  2001 vec.v
-r-xr-xr-x    1 root     root       643405 Feb 28  2001 vec.vi

Could it be that you are using some old kernel, say, older than
2.4.13, that enables the "cruft" option when it sees a big file?
(You should see the corresponding messages in the logs.)

Andries

Re: Why would a valid DVD show zero files on Linux?

[Bryce Nesbitt]

Alan Cox wrote:
> Bryce wrote: 
> > Understood.   However, why can't that combination "just work"?  Changing
> > [mount] every time I switch between sticking in a CD-ROM and DVD-ROM is not cool.
> > Certainly that "other operating system" does not make me do that.
> 
> man fstab
> man ln

Here's the final resolution on this issue:

	fstab(5) now mentions "udf".

	mount(8) now has the key piece of information - "udf
	and iso9660 co-exist on many discs".

	mount -t auto now automounts udf.
	This required scanning the extended area as you can't
	tell from the first VSD.

Most people will never need to think about the issue again, dvd-rom's will
just mount.  Poof.

Thanks for the tips and pointers that helped identify the cause.

			-Bryce