tape changer, but not tape drive

[Adam McDougall]

Dan Langille wrote:
> Adam McDougall wrote:
>> On Tue, Oct 27, 2009 at 09:39:07PM -0400, Dan Langille wrote:
>>
>>   I first encountered this problem in April, now I'm back to it:
>>        
>> http://lists.freebsd.org/pipermail/freebsd-scsi/2008-April/003452.html
>>     In short, the system has tape library.  The library has worked in 
>> the   past (http://www.freebsddiary.org/digital-tl891.php) but now it 
>> does   not.  I can see either the tape library or the tape drive.  
>> Which I see   depends upon the cable configuration.
>>        http://www.freebsddiary.org/images/tape-libraries-cables.jpg
>>     As shown above, that's how I would expect things to work 
>> normally.   However, in that configuration, I do not see the tape 
>> drive.  The cable   going down, goes to the computer.  If I reconnect 
>> that cable to the plug   to the left of the terminator, the system 
>> can see the DLT drive, but not   the tape library.
>>     Under 6.3-STABLE FreeBSD, I can see either one device or the other.
>>     ch0 at ahc0 bus 0 target 0 lun 0
>>   ch0:  Removable Changer SCSI-2 device
>>   ch0: 20.000MB/s transfers (10.000MHz, offset 8, 16bit)
>>   ch0: 10 slots, 1 drive, 1 picker, 0 portals
>>     or
>>     sa0 at ahc0 bus 0 target 1 lun 0
>>   sa0:  Removable Sequential Access SCSI-2 device
>>   sa0: 20.000MB/s transfers (10.000MHz, offset 8, 16bit)
>>   acd0: FAILURE - INQUIRY ILLEGAL REQUEST asc=0x24 ascq=0x00 sks=0x40 
>> 0x00   0x01
>>     Any ideas?
>>     Full dmesg output here:  http://www.langille.org/tmp/dmesg.boot
>>     TIA.
>>   Is it possible the middle cable is broken in some way?  Perhaps you
>> could swap it with another cable to try to find out, such as with
>> the cable going from the library to the 2944 card.  Might be 
>> intermittant
>> and start working if bent or moved. 
>
> I did try that.  I used the cable from my stand-alone DLT drive, which 
> has been used before (and after) and is known to be good.
>
>> Also can you see the connectors
>> inside the library (on the back side of the external plate) to check
>> if they are well seated or damaged?
>
> I'll pull the unit apart and have a look.  I have been in there 
> before.   Since it last worked, the unit has gone through two moves.
>
> > You could also try swapping the
>> first and second connection or the third and fourth, or both, if it is
>> hooked up like I think it is, those should have an equal chance of 
>> working
>> and might reveal a bad port or partially bad port.  
>
> I did try moving the looped cable to plugs 1&2 and connecting my 
> computer to plug 3.
The two plugs for each device (library, tape1, tape2) are probably tied 
directly together in a Y
shape to the internal device so you can use them as an In/Out, so 
putting the looped cable on
plugs 1 and 2 probably does nothing and isolates that device from the 
rest.  As long as the looped
cable is not between 1&2 or 3&4, you can probably use any other order 
although the manufacturer
may have recommendations.  I see nothing wrong with the way you appear 
to have cabled it but
variations may reveal something. 
>
>> Also try leaving off
>> the terminator or one/both ends of the middle cable just to see if the
>> system can tell the difference especially while booting, just to confirm
>> if it makes any negative difference at all.  
>
> OK, I will try that.
>
> Thank you.
>