rescan causes offlined tape to reload

[Alexander Motin]

G. Paul Ziemba wrote:
> mj at feral.com (Matthew Jacob) writes:
> 
>> My recollection is that when you 'eject' a DLT, unless you operate the 
>> handle, or it's part of a changer unit that does it for you, any 
>> subsequent Test Unit Ready will reload it.
> 
>> Other than that, there are couple of candidate changes in the XPT layer 
>> in the time frame you talk of which may be inducing this behavior. Any 
>> way you can get a trace of the SCSI commands sent?
> 
> Hmm. The same drive did not reload the tape upon rescan before I
> upgraded to FreeBSD-stable from Jan 11, so I do not think Test Unit
> Ready is causing it.
> 
> I rebuilt the kernel to set CAMDEBUG. The kernel and userland are
> still the code from FreeBSD current as of 2011-Jan-11.
> 
> It looks as if "camcontrol rescan" generates a command specifically
> to load the media (distinct from the TEST UNIT READY).
> 
> # uname -a
> FreeBSD hairball.ziemba.us 8.2-PRERELEASE FreeBSD 8.2-PRERELEASE #0: Thu Jan 20 20:28:21 PST 2011     root at hairball:/usr/obj/usr/src/sys/GPZ-110111-camdebug  i386
> 
> # camcontrol debug -c 0:4
> Debugging enabled for 0:4:-1
> # camcontrol eject sa0
> Unit stopped successfully, Media ejected
> 
> Jan 20 21:07:26 hairball kernel: (pass2:sym0:0:4:0): LOAD UNLOAD. CDB: 1b 0 0 0 2 0 
> 
> # camcontrol rescan all
> 
> Jan 20 21:08:40 hairball kernel: (probe4:sym0:0:4:0): TEST UNIT READY. CDB: 0 0 0 0 0 0 
> Jan 20 21:08:44 hairball kernel: (probe4:sym0:0:4:0): LOAD UNLOAD. CDB: 1b 0 0 0 3 0 
> Jan 20 21:09:34 hairball kernel: sym0:4:control msgout: 80 6.
> Jan 20 21:09:34 hairball kernel: (probe4:sym0:0:4:0): TEST UNIT READY. CDB: 0 0 0 0 0 0 
> Jan 20 21:09:34 hairball kernel: (probe4:sym0:0:4:0): INQUIRY. CDB: 12 0 0 0 24 0 
> Jan 20 21:09:34 hairball kernel: (probe4:sym0:0:4:0): INQUIRY. CDB: 12 1 0 0 ff 0 
> Jan 20 21:09:34 hairball kernel: (probe4:sym0:0:4:0): INQUIRY. CDB: 12 1 80 0 ff 0 
> Jan 20 21:09:34 hairball kernel: (probe0:sym0:0:4:1): INQUIRY. CDB: 12 20 0 0 24 0 
> Jan 20 21:09:34 hairball kernel: (probe0:sym0:0:4:2): INQUIRY. CDB: 12 40 0 0 24 0 
> Jan 20 21:09:34 hairball kernel: (probe0:sym0:0:4:3): INQUIRY. CDB: 12 60 0 0 24 0 
> Jan 20 21:09:34 hairball kernel: (probe0:sym0:0:4:4): INQUIRY. CDB: 12 80 0 0 24 0 
> Jan 20 21:09:34 hairball kernel: (probe0:sym0:0:4:5): INQUIRY. CDB: 12 a0 0 0 24 0 
> Jan 20 21:09:34 hairball kernel: (probe0:sym0:0:4:6): INQUIRY. CDB: 12 c0 0 0 24 0 
> Jan 20 21:09:34 hairball kernel: (probe0:sym0:0:4:7): INQUIRY. CDB: 12 e0 0 0 24 0 

For the full picture it would be nice to see responses device sent. I
suppose that in response to TUR device returns some status that implies
tray closing/load.

-- 
Alexander Motin