News on: Re: 2.6.3 BUG - can't write DVD-RAM - reported as write-protected

[Thomas Duda <td@linuxgang.com>]

G'day folks...

I am cross-posting this to kernel and scsi because
I think you guys should know about it.

Had some spare time and lots of equipment available,
so I got to investigate this issue a bit further.

Now, I am in shock...

It looks like Linux 2.6.x (tested 2.6.2->2.6.4) doesn't
allow writing to SCSI based DVD-RAM or CD-R anymore at all.
 
I probed several scsi hba models (onboard + isa/pci) from
Initio, Dawicontrol, Tekram and Adaptec.

No luck in writing a single bit onto media..! In every
scsi setup/combination of hardware 2.6.x mounts were
always read-only. Using IDE drives worked flawlessly.
Also checking with a scsi jaz drive seemed to work ok.

Cross checking with linux 2.4.21-192 (Suse) I didn't
encounter any trouble. No matter what scsi setup/combination
I used.

Is someone is going to look into that..? 

thx & regs

td


As a side note - who believes the new aic7xxx scsi driver
has production quality? Not me! Under load this driver seems
to have LOTS of problems (tested with various seagate/ibm/hitachi
disks in single disk configuration). 










Thomas Duda schrieb:
> 
> Hi,
> 
> to me this seems to be a problem with dvdram drives connected to a scsi
> hba.
> I've got exactly the same software setup based on 2.6.2 on 3 systems
> with
> a dvdram drive. One is a Panasonic LFD-201 (SCSI), another one is a
> Panasonic
> LFD-521 (IDE), the third is an LG-4020B (IDE).
> 
> The SCSI LFD-201 is connected to an Adaptec 7890. There is no way I can
> use it to write data. A mount always happens read-only. Even though "Can
> write DVD-RAM" is reported in /proc/sys/dev/cdrom/info.
> 
> Another phenomen: mkfs.ext2 /dev/scd0 runs as usual. No errors or any
> other messages. The drive led lightens up. However - the dvdram doesn't
> have
> an ext2 fs afterwards. If I do a tune2fs -c 0 -t 0 /dev/scd0 it tells me
> "bad superblock".
> 
> The 2 IDE dvdram drives in the other machines perform the task as
> expected.
> 
> If I take the dvdram out of the scsi drive into the ide drives, format
> it with mkfs.ext2, put it back into the scsi drive, then I see an ext2
> fs
> on it.
> 
> Just for clarification: They all workfine with all their speced out
> capabilities
> with plain Suse 9.0 out-of-the-box! (off-course with ide-scsi, kernel
> 2.4.21-192)
> 
> To me this looks like a problem in 2.6.2/3 with scsi connected dvdram
> drives only..?
> So may be the problem lies not in the cdrom stuff but in interfacing
> that to the
> scsi layer..?
> 
> As a remark: I noticed that /proc/sys/dev/cdrom/info doesn't report
> anything
> related to dvd-rw nor dvd+rw write capabilites for the ide based LG
> GSA-4040B
> or the Panasonic LFD-521E (dvd-rw only!). Is this intentional?
> 
> regs
> 
> td
> 
> Jens Axboe schrieb:
> >
> > On Tue, Mar 09 2004, Olaf Fr?czyk wrote:
> > > On Sun, 2004-03-07 at 11:59, Jens Axboe wrote:
> > > > On Fri, Mar 05 2004, Olaf Fr?czyk wrote:
> > > > > On Fri, 2004-03-05 at 09:23, Jens Axboe wrote:
> > > > > > On Thu, Mar 04 2004, Olaf Fr?czyk wrote:
> > > > > > > Hi,
> > > > > > > I switched to 2.6.3 from 2.4.x serie.
> > > > > > > When I mount DVD-RAM it is mounted read-only:
> > > > > > >
> > > > > > > [root@venus olaf]# mount /dev/dvdram /mnt/dvdram
> > > > > > > mount: block device /dev/dvdram is write-protected, mounting read-only
> > > > > > > [root@venus olaf]#
> > > > > > >
> > > > > > > In 2.4 it is mounted correctly as read-write.
> > > > > > >
> > > > > > > Drive: Panasonic LF-201, reported in Linux as:
> > > > > > > MATSHITA        DVD-RAM LF-D200         A120
> > > > > > >
> > > > > > > SCSI controller: Adaptec 2940U2W
> > > > > >
> > > > > > What does cat /proc/sys/dev/cdrom/info say? Do you get any kernel
> > > > > > messages in dmesg when the rw mount fails?
> > > > >
> > > > > I get nothing in /var/log/dmesg and in /var/log/messages
> > > > > In /proc/sys/dev/cdrom/info I get:
> > > > > [olaf@venus olaf]$ cat /proc/sys/dev/cdrom/info
> > > > > CD-ROM information, Id: cdrom.c 3.20 2003/12/17
> > > > >
> > > > > drive name:             sr1     sr0     hdc
> > > > > drive speed:            0       16      44
> > > > > drive # of slots:       1       1       1
> > > > > Can close tray:         1       1       1
> > > > > Can open tray:          1       1       1
> > > > > Can lock tray:          1       1       1
> > > > > Can change speed:       1       1       1
> > > > > Can select disk:        0       0       0
> > > > > Can read multisession:  1       1       1
> > > > > Can read MCN:           1       1       1
> > > > > Reports media changed:  1       1       1
> > > > > Can play audio:         1       1       1
> > > > > Can write CD-R:         0       1       1
> > > > > Can write CD-RW:        0       1       1
> > > > > Can read DVD:           1       0       0
> > > > > Can write DVD-R:        0       0       0
> > > > > Can write DVD-RAM:      1       0       0
> > > > > Can read MRW:           0       0       1
> > > > > Can write MRW:          0       0       1
> > > > >
> > > > > The one I'm mounting is /dev/scd1.
> > > > > As there is capablity to write-protect DVD-RAM disk (like a 1.44"
> > > > > Floppy), I think that the linux kernel interprets some message from
> > > > > device in wrong way.
> > > >
> > > > Please repeat with this patch applied and send back the results, thanks.
> > > >
> > > > ===== drivers/cdrom/cdrom.c 1.48 vs edited =====
> > > > --- 1.48/drivers/cdrom/cdrom.c      Mon Feb  9 21:58:21 2004
> > > > +++ edited/drivers/cdrom/cdrom.c    Sun Mar  7 11:58:40 2004
> > > > @@ -645,9 +645,12 @@
> > > >  {
> > > >     disc_information di;
> > > >
> > > > -   if (cdrom_get_disc_info(cdi, &di))
> > > > +   if (cdrom_get_disc_info(cdi, &di)) {
> > > > +           printk("cdrom: read di failed\n");
> > > >             return 0;
> > > > +   }
> > > >
> > > > +   printk("cdrom: erasable: %d\n", di.erasable);
> > > >     return di.erasable;
> > > >  }
> > > >
> > > I get:
> > > cdrom: read di failed
> >
> > Can you try to instrument drivers/cdrom/cdrom.c:cdrom_get_disc_info()
> > and find out where it fails? Change the cgc.quiet = 1 to a = 0 in there
> > as well (that alone might be enough to pin point the problem).
> >
> > --
> > Jens Axboe
> >
> > -
> > 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/
> 
> -
> 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/