SCSI Tape Drive - LUN Support

Wed Aug 25 19:40:44 UTC 2004

Kenneth Goodwin wrote:
> Unfortunately his original post was in HTML formats and my
> conversion to plain text was not clean, so my original
> response
> may be overlooked....
> 
> If you look at his "cat /proc/scsi/scsi output",
> you will see that his SCSI ids dont make sense, the cdrom
> and the controller
> are at scsi id 0 and the tape drive is at 6. Only the
> controller should be 0,
> that means he has an id conflict between the devices and
> needs to adjust the scsi id jumpers or switches
> (unless he is plugging into a scsi backplane which would
> normally set the scsi ID for him, which is
> not likely with a tape/cdrom setup)
> 
> Of course, why he is using a RAID controller to drive a
> cdrom and a tape drive
> instead of a plain scsi controller is another question....
> unless it is multichannel card and he has this stuff on the
> non-raid channel.

Uh, the CD-ROM and the DLT are on separate controllers, so the SCSI IDs
don't conflict.  Look at the output:

 >> Attached devices:
 >> Host: scsi0 Channel: 00 Id: 00 Lun: 00
 >>   Vendor: DELL     Model: PERCRAID RAID5   Rev: V1.0
 >>   Type:   Direct-Access                    ANSI SCSI
 >> revision: 02
 >> Host: scsi1 Channel: 00 Id: 00 Lun: 00
 >>   Vendor: TEAC     Model: CD-224E          Rev: K.9A
 >>   Type:   CD-ROM                           ANSI SCSI
 >> revision: 02

Note the "scsi0" and "scsi1" bits.

SCSI controllers, BTW, usually use SCSI ID 7, not 0.  If you go back to
the old Sun Microsystems days of eight or 10 years ago (when they were
the largest user of SCSI devices), they normally laid things out thusly:

	SCSI ID		Device
	   0		Open
	   1		Open
	   2		Open
	   3		Hard Drive
	   4		Tape (normally a DC5150 or DC5250)
	   5		Open
	   6		CD-ROM
	   7		Controller

Their firmware swapped SCSI IDs 0 and 3, so the hard drive, while
physically jumpered to ID3, showed up as ID0 to the software and any
device physically jumpered to ID0 showed up as ID3 to software.  Just
why they did this is not clear, other than the fact that the drive would
ship with two jumpers, so you could make any other ID you wanted except
7 (which would conflict with the controller).

On a Linux system, and assuming both drivers were loaded (an "lsmod"
would be nice here), a SCSI CD would show up as /dev/scd0, the tape
would appear as /dev/st0.  The contents of /var/log/dmesg would be of
help also, to see if the devices were seen at boot.

>> -----Original Message-----
>> From: redhat-install-list-bounces at redhat.com
>> [mailto:redhat-install-list-bounces at redhat.com]On Behalf
> 
> Of Darryl W.
> 
>> DeLao Jr.
>> Sent: Wednesday, August 25, 2004 10:23 AM
>> To: 'Getting started with Red Hat Linux'
>> Subject: RE: SCSI Tape Drive - LUN Support
>>
>>
>> I have heard that it may have something to do with LUN
>> support in the Kernel
>> and that it is not enabled, and that it requires a
>> re-compile of some sort.
>>
>>
>>
>> -----Original Message-----
>> From: redhat-install-list-bounces at redhat.com
>> [mailto:redhat-install-list-bounces at redhat.com] On Behalf
> 
> Of
> 
>> Kenneth Goodwin
>> Sent: Wednesday, August 25, 2004 8:56 AM
>> To: ddelao at oucpm.org; 'Getting started with Red Hat
> 
> Linux'
> 
>> Subject: RE: SCSI Tape Drive - LUN Support
>>
>> -----Original Message-----
>> From: redhat-install-list-bounces at redhat.com
>> [mailto:redhat-install-list-bounces at redhat.com]On Behalf
> 
> Of
> 
>> Darryl W. DeLao Jr.
>> Sent: Wednesday, August 25, 2004 9:44 AM
>> To: rhn-users at redhat.com; redhat-list at redhat.com;
>> redhat-install-list at redhat.com
>> Subject: SCSI Tape Drive - LUN Support
>>
>>
>> Hello everyone,
>>
>> I recently installed an Adaptec SCSI Card in my PowerEdge
>> 2650.  Attached to the Adaptec card is 1 DLT VS160 Drive.
>> When I fire up the server, the SCSI BIOS loads and
> 
> detects
> 
>> everything perfectly.  When RHEL ES 3.0 loads, it does
> 
> not
> 
>> see the DLT Drive.  When I do a lsmod from the command
> 
> line,
> 
>> I see my RAID and the CD-ROM drive listed.  Upon checking
>> the /etc/modules.conf file I see the following listed:
>>
>> alias eth0 e1000
>> alias eth1 tg3
>> alias eth2 tg3
>> alias scsi_hostadapter aacraid
>> alias usb-controller usb-ohci
>> alias scsi_hostadapter1 aic7xxx
>>
>>
>> Upon doing a modprobe aic7xxx from the command line, I
> 
> see
> 
>> this after doing cat /proc/scsi/scsi
>>
>> Attached devices:
>> Host: scsi0 Channel: 00 Id: 00 Lun: 00
>>   Vendor: DELL     Model: PERCRAID RAID5   Rev: V1.0
>>   Type:   Direct-Access                    ANSI SCSI
>> revision: 02
>> Host: scsi1 Channel: 00 Id: 00 Lun: 00
>>   Vendor: TEAC     Model: CD-224E          Rev: K.9A
>>   Type:   CD-ROM                           ANSI SCSI
>> revision: 02
>>
>> ==== Please dont post in HTML formats =============
>>
>> The probable cause of your problem is that the SCSI
>> controller
>> and the CDROM drive
>> both appear to be set to the same SCSI ID of 0, Jump and
>> adjust the scsi id of the cdrom so
>> it is not  0 or 6. It may also be that the CDROM and the
>> tape drive are both set to 6 (cause of your original
>> problem) and that the cdrom is taking itself off-line
>> when it detects the ID conflict.
>>
>> ========================================================
>>
>>
>> Host: scsi2 Channel: 00 Id: 06 Lun: 00
>>   Vendor: QUANTUM  Model: DLT VS160        Rev: 1E00
>>   Type:   Sequential-Access                ANSI SCSI
>> revision: 02
>>
>> The DLT is now listed and I am now able to fire up the
>> software and use the DLT.  However, now I can not use the
>> CD-ROM drive.  I am unable to mount it or anything.  When
> 
> I
> 
>> reboot, everything resets and I have to modprobe aic7xxx
>> again in order to use the DLT.  Does anyone know what I
> 
> need
> 
>> to do or enable or what not so that I can use both the
>> CD-ROM and the DLTVS160 after a reboot without having to
>> issue a command to use the DLTVS160?
>>
>> Thanks,
>> Darryl
>>
>>
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-- 
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- Rick Stevens, Senior Systems Engineer     rstevens at vitalstream.com -
- VitalStream, Inc.                       http://www.vitalstream.com -
-                                                                    -
-             To iterate is human, to recurse, divine.               -
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