'camcontrol rescan all' does not find the attached tape drive

Scott Long scottl at samsco.org
Wed May 3 19:02:33 UTC 2006

Adam wrote:
> Hi Scott.
> I am grateful for and honored by your response.  I am pretty much stuck
> with the asr device for now, but I would love a list of quality hardware
> raid devices and related management utilities that can be used with
> freebsd/linux.

Is there any chance that you could just plug a simple Adaptec 2940 or 
even a low-end TekRam card into an unused slot on your motherboard?

> I can get raidutil (sysutils/asr-utils) to recognize a tape drive that was
> not present during boot by direct inquiry (raidutil -I d0b1t6d0).
> Unfortunately, camcontrol rescan all will not see the device unless it was
> present at boot.  If I boot with one tape drive attached, power it down,
> camcontrol rescan all (and confirm that it is gone), attach a different
> tape drive (use the appropriate raidutil -I d0b1t#d0 command to tell the
> asr0 where the tape drive can be found), a camcontrol rescan of the bus
> with the tape drive never returns nor can it be killed.  If anyone wants
> more data or testing on that, I'll be happy to do what I can.
> I can accept that the issue is the vendor/hardware (asr) and not the
> software (freebsd).  Thanks for pointing me in the right direction.

The view of the SCSI buses that CAM sees is filtered by the ASR
hardware.  The driver doesn't have direct access to the SCSI buses, it
just has access to virtual devices that the firmware has created to
represent the physical devices.  You are at the mercy of the games that
the firmware is playing, unfortunately.

In the past, doing a rescan from the utility 'fixed' these problems, but
it's probably been 5 years since I last dealt with ASR at this level.
 From an architectural standpoint, I have a hard time feeling good about
mixing RAID functionality and SCSI functionality on a RAID controller.
But I also recognize that there are often limitations on PCI slots, so
mixing cannot be avoided.


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