I’m seeing some strange behavior when enumerating SCSI devices under Windows
2000 (both Gold and SP2). I have a SCSI Processor device connected to a
Adaptec PCMCIA SCSI card using the out-of-the-box drivers. When I boot the
computer, Windows 2000 does not enumerate the processor device. But if I go
into Device Manager and click the “Rescan for new plug-and-play devices”
button, it finds it OK and installs it using our .INF file. I can then
access the device. When I reboot, I have to go through the rescan again
before I can use the device. However, if I have another device (a tape
drive) on the same SCSI bus, both devices enumerate on boot. I tried
changing the SCSI ID of the processor device (putting it both before and
after the tape device) to see if it was a timing problem. But as long as
the tape device was on the bus, the processor device was always enumerated.
Remove the tape device, and it no longer enumerated.
I am stumped. Any ideas on why this might be happening? Any workarounds?
Best regards,
-Dan
Dan Germann
xxxxx@nospam.visi.com
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Since SCSI Processor devices are so exceptionally rare, I doubt Win2k has ever
been tested with one. What you’re witnessing could easily be a bug/limitation
in Win2k, SCSIPORT or the controller miniport driver, or all three.
One possibility though; PCMCIA SCSI controllers do not supply termination power
to the SCSI bus (ie pin26/TERMPWR) does have the applied voltage in order to
“energize” the bus. External tape drives typically do provide TERMPWR, so if
your PROC device wasn’t supplying TERMPWR chances are it would make it
impossible for the device to be enumerated at all. The reason PCMCIA cards
typically do not supply TERMPWR is that it is “costly” on the limited power
available in a laptop environment. The only thing I can think of is that once
Win2k is booted and the miniport driver realizes that the system is on AC power,
maybe it throws out TERMPWR. This, I would think is rather unlikely, but is the
only scenario I can think of that could think of (outside the bug/limitation
scenario) where you have this problem. Having the tape drive present would
allow the device to be enumerated always since TERMPWR would always be present.
Regards,
Paul Bunn, UltraBac.com, 425-644-6000
Microsoft MVP - WindowsNT/2000
http://www.ultrabac.com
-----Original Message-----
From: Daniel E. Germann [mailto:xxxxx@nospam.visi.com]
Sent: Thursday, October 18, 2001 5:57 AM
To: NT Developers Interest List
Subject: [ntdev] SCSI Processor devices and Windows 2000
I’m seeing some strange behavior when enumerating SCSI devices under Windows
2000 (both Gold and SP2). I have a SCSI Processor device connected to a
Adaptec PCMCIA SCSI card using the out-of-the-box drivers. When I boot the
computer, Windows 2000 does not enumerate the processor device. But if I go
into Device Manager and click the “Rescan for new plug-and-play devices”
button, it finds it OK and installs it using our .INF file. I can then
access the device. When I reboot, I have to go through the rescan again
before I can use the device. However, if I have another device (a tape
drive) on the same SCSI bus, both devices enumerate on boot. I tried
changing the SCSI ID of the processor device (putting it both before and
after the tape device) to see if it was a timing problem. But as long as
the tape device was on the bus, the processor device was always enumerated.
Remove the tape device, and it no longer enumerated.
I am stumped. Any ideas on why this might be happening? Any workarounds?
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