[nflug] CD/DVD drives not working in linux

David J. Andruczyk djandruczyk at yahoo.com
Tue Mar 14 08:21:47 EST 2006



--- "Robert F. Stockdale IV" <javabob at adelphia.net> wrote:

> If it was a termination problem how could lsscsi report what drives
> are on the scsi channel? 
> Don't termination problems prevent the whole daisy chain from
> operating?
> Bob

Not necessarily.  If hte bus is cimpletely unterminated, usually things
won't be detected.  but if the bus is dual or multi-terminated (i.e.
several devices have termination enabled (non LVD devices as LVD drives
don't have onboard terminators)  they can usualyl be detected and the
bus usually works UP to the point of the first termination. so if your
bus is arranged physically like so

HBA (2940 card)   ID-0 (disk)  ID-1 (disk)  CD (term'd) (CD (term'd)
   -------------------|------------|------------|------------|

Then on power up the HBA, the two hard disks and hte one cdrom would
show up all the time but the one on the ned may or may not show up due
to the dual termination of the last two devices.  Basically anything
past the first terminator will be "hidden" or intermittently hidden.

When the bus is "quiet"  i.e. not in use,  minimal/no I/O going across
it a bus scan will usually find all the devices even if the termination
is hosed up.  Once I/O is happening though (burning  a CD) the signal
levels on the bus past the first terminator go down to close to zero
resulting in I/O errors to the device beyond the first terminator.

I'd remove one CDrom drive and try with just one, and recheck the
termination settings of ALL devices on the bus (check the jumper pages
for each drive you have and the ACARD bridge.)

I knew an individual who setup an external scsi chassis and enabled
termination on all 6 drives.  On powerup the scsi controller would
detect usually 4-5 of them (and it was an adaptec controller). He could
do I/O to the first drive in the chain but trying to do anything with
any other drives resulted in severe I/O errors and continuous scsi bus
resets.  Once I pulled out the excessive terminators all was good and
the disks all were detected and all worked as expected.


> 
> David J. Andruczyk wrote:
> > 
> > --- "Robert F. Stockdale IV" <javabob at adelphia.net> wrote:
> > 
> > 
> >>Thanks Dave:
> >>	Unfortunately it didn't work. Actually I had it that way before. I
> >>emerged lsscsi and it shows:
> >>java bob # lsscsi
> >>[0:0:1:0]    cd/dvd  PIONEER  DVD-ROM DVD-303  1.09  /dev/sr0
> >>[0:0:4:0]    cd/dvd  YAMAHA   CRW-F1S          1.0c  /dev/sr1
> >>[1:0:0:0]    cd/dvd  DVDRW    DRW-3S163        BSG2  /dev/sr2
> >>[2:0:0:0]    disk    SEAGATE  ST336607LW       0006  /dev/sda
> >>[2:0:1:0]    disk    SEAGATE  ST336607LW       0006  /dev/sdb
> >>[2:0:2:0]    disk    SEAGATE  ST336607LW       0006  /dev/sdc
> >>
> >>The lsmod command you gave me shows:
> >>java bob # lsmod |grep sr_mod
> >>sr_mod                 15268  3
> >>cdrom                  38560  1 sr_mod
> >>
> >>
> >>Finally, I ran dmesg and it revealed /dev/sr1 having an ioctl
> error.
> >>In fact the tail on it 
> >>looks like:
> >>
> >>sr1: CDROM (ioctl) error, command: <6>cdb[0]=0x0 00 00 00 00 00 00
> >>sr: Current: sense key=0x3
> >>     ASC=0x57 ASCQ=0x0
> >>sr1: CDROM (ioctl) error, command: <6>cdb[0]=0x0 00 00 00 00 00 00
> >>sr: Current: sense key=0x3
> >>     ASC=0x57 ASCQ=0x0
> >>sr0: CDROM not ready.  Make sure there is a disc in the drive.
> >>cdrom: open failed.
> >>cdrom: open failed.
> >>scsi1 (0:0): rejecting I/O to offline device
> >>
> >>
> >>So it looks like bus A on my Adaptec 2940UW is giving me problems.
> >>Do you have any other ideas?
> > 
> > 
> > Sounds like either A. a failed device or SCSI bridge, or B,
> termination
> > issues. (B is more likely).
> > 
> > Which ACARD bridge are you using the 7722, or the 7726?   The 7722
> are
> > ONLY for ATAPI (CD/DVD) devices, the 7726 is ONLY for IDE disks.
> > 
> >   How is the SCSI bus configured termination wise?  The bus should
> be
> > terminated ONLY and I mean ONLY at it's ends.  If you have
> termination
> > enabled at multiple points (aside from the ends) the SCSI bus will
> have
> > erratic problems or not work at all. (some devices may go offline,
> or
> > throw errors, whereas others can and may work fine.)
> > 
> > Typically the adaptec card will auto-terminate at it's end,  there
> > should be a terminator at the end of the bus.
> > 
> > 
> > 
> > Dave J. Andruczyk
> > 
> > __________________________________________________
> > Do You Yahoo!?
> > Tired of spam?  Yahoo! Mail has the best spam protection around 
> > http://mail.yahoo.com 
> > _______________________________________________
> > nflug mailing list
> > nflug at nflug.org
> > http://www.nflug.org/mailman/listinfo/nflug
> > 
> _______________________________________________
> nflug mailing list
> nflug at nflug.org
> http://www.nflug.org/mailman/listinfo/nflug
> 


Dave J. Andruczyk

__________________________________________________
Do You Yahoo!?
Tired of spam?  Yahoo! Mail has the best spam protection around 
http://mail.yahoo.com 
_______________________________________________
nflug mailing list
nflug at nflug.org
http://www.nflug.org/mailman/listinfo/nflug



More information about the nflug mailing list