SCSI controller problems

Jeff Vian jvian10 at charter.net
Mon Jul 12 05:52:15 UTC 2004


On Sun, 2004-07-11 at 23:49, Stewart Nelson wrote:
> Hi Jeff,
> 
> Thanks for the quick reply.
> 
> >> sym53c8xx: at PCI bus 3, device 12, function 0
> >> sym53c8xx: setting PCI_COMMAND_PARITY...(fix-up)
> >> sym53c8xx: 53c875 detected with Symbios NVRAM
> >> sym53c875-0: rev 0x26 on pci bus 3 device 12 function 0 irq 5
> >> sym53c875-0: Symbios format NVRAM, ID 7, Fast-20, Parity Checking
> >> sym53c875-0: on-chip RAM at 0xfeafd000
> >> sym53c875-0: restart (scsi reset).
> >> sym53c875-0: Downloading SCSI SCRIPTS.
> >> scsi1 : sym53c8xx-1.7.3c-20010512
> >> blk: queue dc299c18, I/O limit 4095Mb (mask 0xffffffff)
> >>   Vendor: SONY      Model: SDT-7000          Rev: T306
> >>   Type:   Sequential-Access                  ANSI SCSI revision: 02
> >> blk: queue dc299a18, I/O limit 4095Mb (mask 0xffffffff)
> >> Attached scsi CD-ROM sr0 at scsi0, channel 0, id 0, lun 0
> >> sr0: scsi3-mmc drive: 32x/32x writer dvd-ram cd/rw xa/form2 cdda tray
> >> st: Version 20030406, bufsize 32768, max init. bufs 4, s/g segs 16
> >> Attached scsi tape st0 at scsi1, channel 0, id 0, lun 0
> >> sym53c875-0-<0,*>: FAST-10 SCSI 10.0 MB/s (100.0 ns, offset 15)
> >> sym53c875-0: detaching ...
> >> sym53c875-0: resetting chip
> >> scsi : 1 host left.
> 
> > Have you checked the scsi ID on both devices??  If they are the same it
> > WILL NOT work.
> 
> I realize that, but am still in the early stages of testing,
> and only physically connect one device at a time (shutting down and
> powering off, before moving the cable to the other device).
> 
> In the example above, the DAT was connected to the SCSI bus,
> and the DVD-RAM connected via IDE.  Fedora allocated scsi0 to
> the 'SCSI host adapter emulation for IDE ATAPI devices' and
> scsi1 to the 53c875 hardware controller.  The DVD-RAM is on
> (virtual) ID 0 of scsi0 and the DAT is on ID 0 of scsi1, so there
> should not be a conflict.
> 
> I tried not connecting anything to the secondary IDE port;
> scsi0 is still assigned to emulation (with no devices),
> and the tape on scsi1 still does not work.  Also tried the
> tape on ID 1, to no avail.
> 
> I discovered that the problem is related to the 'detaching ...'
> that occurs.  If I manually modprobe the adapter, the
> device gets attached again and it is accessible :)
> Unfortunately, this is not a complete workaround, because
> e.g. running Hardware Browser causes it to get detached
> again.
> 
> Any ideas on why the detach occurs?
> 
> Thanks,
> 
> Stewart
> 

I missed the fact this shows as 2 scsi adapters. :-(

Possibly termination causing the disconnect?  

In general, scsi buses must be terminated at both ends.  With only one
device attached on the cable (other than the adapter) it should be
terminated either at the end of the cable or at the device (which should
be at the end of the cable if no termination is there).

I found that with only one drive (a Maxtor ultra 160  that cannot be
self-terminated) that I can get by without terminating the drive but it
is the only device on the cable. (there is some penalty in performance,
and the adapter is only scsi FW.)  However, if there is a second device
attached nothing works until I add a terminator.  I had to order a cable
with termination on the cable since the drive cannot provide the
termination for this.






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