Re: Tape drive problem.

["Jose M. Sanchez" <opjose ex-pressnet com>]

Some scsi implementations are better than other dealing with "marginal"
voltage levels.

Your hard drive may be reading the SCSI signals properly because their
thresh hold level is a little lower than your tape drive.

Normally faulty termination or SCSI termination power settings are to blame.

Most newer drives handle SCSI termination power automatically. Some units
still have problems with this and require that ONLY two devices be supplying
terminator power on the chain.

This is NOT the same as the terminator itself!

I've seen instances where a perfectly working set of drives will start
loosing a single drive. That affected drive seems to have all sorts of
command and I/O problems. Moving it elsewhere on the chain or moving it to
another machine, eliminates the problems...

Further investigation (with a scope) shows that the overall voltages are
either too high or too low, even though nothing has changed. Removing one
particular device on the chain brings things back within norms.

Normally the circuit board on the culprit needs to be changed out.

The kicker is that the affected device continues to function NORMALLY.

-JMS

-----Original Message-----
From: Randy Carpenter <rcarpen celt network1 net>
To: Jose M. Sanchez <opjose ex-pressnet com>
Cc: redhat-list redhat com <redhat-list redhat com>
Date: Wednesday, September 30, 1998 7:58 AM
Subject: Re: Tape drive problem.


>
>ARGGG! :)  Everything works fine with the hard drives, even when I get
>these errors...  Why would it only blow up with a slow tape drive?
>*grumble grumble*  I'll try a different cable... thanks.
>
>
>> Change your controller and cable.
>>
>> Something is amiss with the I/O buffering IC's, probably due to a short.
>>
>> -JMS
>>
>> -----Original Message-----
>> From: Randy Carpenter <rcarpen celt network1 net>
>> To: redhat-list redhat com <redhat-list redhat com>
>> Date: Wednesday, September 30, 1998 7:20 AM
>> Subject: Tape drive problem.
>>
>>
>> >Okay...  this is really getting on my nerves...
>> >
>> >All of a sudden, the tape drive on one of our servers started to act
>> >funny...  Now, whenever I try to run an mt command or dump, I get:
>> >
>> >/dev/nst0: I/O error
>> >
>> >I get the following kernel messages in the logs:
>> >
>> >Sep 30 01:21:01 cable kernel: st0: Error with sense data: extra data not
>> > valid Current error st09:00: sns = 70  4
>> >Sep 30 01:21:01 cable kernel: ASC=44 ASCQ= 0
>> >Sep 30 01:21:01 cable kernel: Raw sense data:0x70 0x00 0x04 0x00 0x00
0x00
>> > 0x00 0x0a 0x00 0x00 0x00 0x00 0x44 0x00 0x00 0x00
>> >
>> >This is repeated numerous times.  The drive is an HP t4000, scsi.  Just
>> >now, I hooked up a brand new Segate 4/8GB DAT drive, and I get the same
>> >results.   Where do I look to fix such a problem?   I don't see how it
>> >could be the scsi card or motherboard or anything else, since the system
>> >runs fine otherwise.  Any ideas?
>> >
>> >thanks.
>> >
>> >--------------------------------------------------------------------
>> >Randy Carpenter - UNIX Systems Admin             First Network Group
>> >rcarpen celt network1 net                        Wapakoneta, OH
>> >--------------------------------------------------------------------
>> >
>> >
>> >--
>> >  PLEASE read the Red Hat FAQ, Tips, Errata and the MAILING LIST
ARCHIVES!
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>> >         To unsubscribe: mail redhat-list-request redhat com with
>> >                       "unsubscribe" as the Subject.
>> >
>>
>>
>>
>> --
>>   PLEASE read the Red Hat FAQ, Tips, Errata and the MAILING LIST
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>
>
>--
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