Anybody with SCSI Know How still reading this newsgroup ?

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Peter Dassow

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Jan 27, 2017, 3:49:54 PM1/27/17
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Is anybody with SCSI Know How still reading this newsgroup ?
I've an external HP LTO-2 streamer which works well with a LSI 20160
controller, and also with an Adaptec 19160.
But I've also a Christie LTO-3 streamer which is NOT detected at boot
time from the controller, *regardless* if the SCSI bus is terminated or
not terminated. Btw. the adaptec controller reports even if a device is
properly bus terminated, so you can't do anything wrong.

When I booted up with the connected LTO-2 streamer, but then exchanging
the streamer with the LTO-3 one, I was able to use/control the LTO-3
streamer, and also to work with LTO-3 tapes.

But exchanging the streamer device everytime AFTER I booted the PC, just
to be able to use the external device would not make sense.

What can be the reason that the LTO-3 streamer is NOT detected by the
SCSI controller, but can be used when booted with the LTO-2 streamer and
then be exchanged with the LTO-3 streamer ?

Any further tipps welcome.

Michael Bäuerle

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Jan 28, 2017, 5:22:19 AM1/28/17
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Peter Dassow wrote:
>
> [...]
> I've an external HP LTO-2 streamer which works well with a LSI 20160
> controller, and also with an Adaptec 19160.
> But I've also a Christie LTO-3 streamer which is NOT detected at boot
> time from the controller, *regardless* if the SCSI bus is terminated or
> not terminated. Btw. the adaptec controller reports even if a device is
> properly bus terminated, so you can't do anything wrong.
>
> When I booted up with the connected LTO-2 streamer, but then exchanging
> the streamer with the LTO-3 one, I was able to use/control the LTO-3
> streamer, and also to work with LTO-3 tapes.

I assume that this only works if both drives are configured to the same
SCSI ID.

> But exchanging the streamer device everytime AFTER I booted the PC,
> just to be able to use the external device would not make sense.

Yes. And because the formerly negotated transfer agreement must be
supported, this has worked only by coincidence. In the other direction
(replacing a new drive with an older one), chances are higher that this
will not be the case.

But nevertheless it was a good method to verify that the interface of
the LTO3 drive is not damaged in a way that prevents command execution.

> What can be the reason that the LTO-3 streamer is NOT detected by the
> SCSI controller, but can be used when booted with the LTO-2 streamer
> and then be exchanged with the LTO-3 streamer ?

I have not seen this problem for decades. In the early days there were
SCSI devices with a command set that lacks INQUIRY. This is the command
every modern host uses to query information about a SCSI device.
A short time later this command was defined as a mandatory command for
every SCSI device. Is it possible that your LTO3 drive uses a custom
firmware which intentionally lacks the INQUIRY command?
(Maybe the vendor explicitly wants that the drives only work with their
equipment)

Another less likely problem may be the time a target device requires to
become ready after power-on or a bus reset. For power-on the SPI5
document recommends 10s, for reset 250ms. Many hosts will timeout before
these values to speed up the device scan.

Peter Dassow

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Feb 1, 2017, 6:42:10 PM2/1/17
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On 28.01.2017 at 11:21 Michael Bäuerle wrote:
>
>> What can be the reason that the LTO-3 streamer is NOT detected by the
>> SCSI controller, but can be used when booted with the LTO-2 streamer
>> and then be exchanged with the LTO-3 streamer ?
>
> I have not seen this problem for decades. In the early days there were
> SCSI devices with a command set that lacks INQUIRY. This is the command
> every modern host uses to query information about a SCSI device.
> A short time later this command was defined as a mandatory command for
> every SCSI device. Is it possible that your LTO3 drive uses a custom
> firmware which intentionally lacks the INQUIRY command?
> (Maybe the vendor explicitly wants that the drives only work with their
> equipment)

Indeed, that's what I expected - Christie is not a vendor for enduser
equipment. But I didn't read anything about "Christie SCSI controller",
so I thought there might be an interfacing problem.
Because I tested it with meanwhile TWO controller cards, I am out of
ideas now.

>
> Another less likely problem may be the time a target device requires to
> become ready after power-on or a bus reset. For power-on the SPI5
> document recommends 10s, for reset 250ms. Many hosts will timeout before
> these values to speed up the device scan.
>

I powered the (external) tape drive 20-30 seconds on, before I boot my
PC, so this should be not the case.

Michael Bäuerle

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Feb 2, 2017, 5:08:04 AM2/2/17
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Peter Dassow wrote:
> On 28.01.2017 at 11:21 Michael Bäuerle wrote:
> > Peter Dassow wrote:
> > >
> > > What can be the reason that the LTO-3 streamer is NOT detected by the
> > > SCSI controller, but can be used when booted with the LTO-2 streamer
> > > and then be exchanged with the LTO-3 streamer ?
> >
> > I have not seen this problem for decades. In the early days there were
> > SCSI devices with a command set that lacks INQUIRY. This is the command
> > every modern host uses to query information about a SCSI device.
> > A short time later this command was defined as a mandatory command for
> > every SCSI device. Is it possible that your LTO3 drive uses a custom
> > firmware which intentionally lacks the INQUIRY command?
> > (Maybe the vendor explicitly wants that the drives only work with their
> > equipment)
>
> Indeed, that's what I expected - Christie is not a vendor for enduser
> equipment. But I didn't read anything about "Christie SCSI controller",
> so I thought there might be an interfacing problem.

No need for special hardware if only the detection process is different.
Operating system drivers that allow manual device configuration would
be sufficient.

> Because I tested it with meanwhile TWO controller cards, I am out of
> ideas now.

Have you checked whether the original manufacturer of the drive hardware
allows users to upgrade the firmware? Maybe a standard firmware can be
used with your drive. There is a chance to brick the drive, but if
otherwise it is not really usable too - maybe worth a try.

Peter Dassow

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Feb 6, 2017, 2:07:10 PM2/6/17
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On 02.02.2017 at 11:07 Michael Bäuerle wrote:
>
> Have you checked whether the original manufacturer of the drive hardware
> allows users to upgrade the firmware? Maybe a standard firmware can be
> used with your drive. There is a chance to brick the drive, but if
> otherwise it is not really usable too - maybe worth a try.
>

Inside the external case a Quantum TC-L32AX is found.
Not sure if there is an EPROM which I can replace, or an EEPROM I can
reach via an update software.

Regards Peter

Jeff Jonas

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Feb 12, 2017, 11:16:03 PM2/12/17
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> Inside the external case a Quantum TC-L32AX is found.

a) did you try other SCSI IDs on it?

b) Is the Host Adapter (controller) set to send "start unit"
upon initialization / power-up?
Some hard drives are configured to wait for that command to spin up.
Perhaps the tape drive needs it too.

-- jeff jonas

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