tape changer, but not tape drive

[Dan Langille]

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.

> 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.