Mailinglist Archive: opensuse (929 mails)

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Re: [opensuse] SCSI Problem
On Fri, 14 Mar 2014 10:28:07 +0100
Meike Stone wrote:

Hello,

I've a problem with the scsi subsystem
We have tape library connected over SAN with ten tape devices.
The devices are seen with lssci and the mappings between the generic
scsi devices and the scsi addresses (H:B:T:L) with sg_map -x.
This looks like:
..
/dev/sg235 7 0 0 0 12
/dev/sg236 7 0 0 1 8
/dev/sg237 7 0 0 2 8
/dev/sg238 7 0 1 0 1 /dev/nst0
/dev/sg239 7 0 2 0 1 /dev/nst1
/dev/sg240 7 0 2 1 8
/dev/sg241 7 0 3 0 1 /dev/nst2
/dev/sg242 7 0 4 0 1 /dev/nst3
...

But sometimes I get the messages from sg_map:
"Strange, could not find device /dev/nstxx mapped to sg device??"
on top of the output and at the end the strange "scsi address" (see
sg254) /dev/sg252 9 0 1 0 1
/dev/sg253 10 0 0 0 1 /dev/nst11
/dev/sg254 -2 -2 -2 -2 -2
/dev/sg255 10 0 2 0 1

The device file /dev/sg254 exist in the /dev directory.
If I disconnect the device, the device file will be removed and if I
reconnect again, the device file is create automatically.

Does anyone has a clue, why this strange behavior occurs?

thanks Meike

Hello Meike,

Do you know the manufacturer, model & serial numbers for the subsystem?
For the tape drives? These devices usually have firmware, too, so you
want those version numbers as well. Is the subsystem single-ended SCSI
or is it differentially driven? And which SCSI flavor? (1, 2, fast,
fast-wide, and so on...?) The same information is helpful to have for
the host controller, as well, including firmware version. If it turns
out that all the hardware, including controllers, cables, connectors and
terminators, are in good repair you'll need this information to start
debugging at the driver / firmware / software level.

The above being said, the first thing I would check is the affected
device. Is it the last on the bus, i.e. furthest away, electrically,
from the host controller? If so, it needs to be properly terminated.
Inspect the length, condition and quality of all the cables, connectors
and sockets and the terminator, too, to confirm that everything is
within the physical design specifications. Likewise, check the
condition of the subsystem power supply and wiring. It could be the
affected device is receiving marginal or 'flaky' power due to the
supply degrading over time.

hth & regards,

Carl

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