From: James Hammett (james@che.utexas.edu)
Date: Thu Aug 07 2003 - 14:19:45 EDT
Selden Ball wrote that the system has issues with running devices on
both the internal and external ports of the Qlogic SCSI controller.
I'm thinking the new HD is less tolerant with this sort of problem.
Removing the external devices solved it. I then had the user (remote
site) purchase an external case and move all of the internal drives
to it. This worked as well.
Thanks for the help,
James
>Date: Tue, 05 Aug 2003 15:50:55 -0400 (EDT)
>From: Selden E Ball Jr <seb@lepp.cornell.edu>
>Subject: Re: Problems with 36 GB SCSI Drive on 433au
>Sender: Selden E Ball Jr <SEB@LNS62.LNS.CORNELL.EDU>
>To: James Hammett <james@che.utexas.edu>
>
>James,
>
>You wrote
>
>>I recently upgraded the OS on a 433au box to Digital 5.1a. The
>>upgrade appeared to go fine.
>
>433au: that means you're using a PCI SCSI host adaptor,
>most likely the Qlogic model that originally came with the system.
>Is that right?
>(I'll assume so.)
>
>>Shortly after that I installed a new 36 GB SCSI HD into the system.
>>Initially the system appeared to be putting the drive to sleep and
>>then it was unable to reawaken it. I used the kernel tuner and
>>disabled power saving features. This changed the nature of the
>>problem, but it did not solve it. (Dr Blinn with HP helped in
>>figuring this part out).
>
>>Currently I am able to see the hd, partition, and mount the hd and
>>maybe write a small number of files. However when I try and do
>>anything even remotely intensive, it hangs. (Everything).
>
>Is this new disk connected to the external port on the host adaptor?
>Does the system also have an internal system disk?
>If so, that's your problem.
>
>The Qlogic card can be used with internal disks or with external disks
>but not with both.
>
>The Qlogic card includes automatic bus termination circuitry
>which is *extremely* unreliable. Most likely you now have three
>terminations on your SCSI bus: one at the end of the internal SCSI
>cable near your system disk, one on the SCSI card, and one at the
>end of the external SCSI cable. That cannot work. A SCSI bus will
>only
>work reliably if it has two terminations, one at each end of the bus.
>
>Even when the termination does work, you've got the problem of the
>cable length. You're only allowed 2 meters of SCSI cabling on that
>type of SCSI bus. More than 1 meter is eaten up by the cabling
>inside the case
>and the SCSI interfaces on the disks and host adaptor.
>
>If this is your situation, I'd suggest moving all of the internal
>disks into external enclosures. Adding internal disks causes the
>entire
>system to overheat because there simply isn't enough airflow around
>them. The internal disks will die after a year or so.
>
>>Looking at the logs I don't see anything specific.
>
>You wouldn't: the entire SCSI bus is locking up, preventing
>the system from writing anything to the log files on the system disk.
>
>Can you guess how I know all this? ;-)
>Let's just say we found out the hard way.
>
>We have maybe a half-dozen 433s, plus maybe 8 or 10 500s (both styles)
>and about twice that number of 600au systems.
>
>If you only have to support a single 433, and if you're willing to
>make some non-standard changes, and if you have a PC that you can
>use, then you can use a stand-alone PC based utility to manually
>configure the termination settings on the Qlogic card. Qlogic used
>to provide a utility on floppy that would configure the SCSI card.
>I don't know if it's still available. That same model of card was
>also sold for use with PCs. Of course, this is *not* supported by
>DEC/Compaq/HP.
>
>I hope this clarifies things a little.
>
>Good luck!
>
>Selden
>======
>Selden E. Ball, Jr.
>
>Cornell University Voice: +1-607-255-0688
>Laboratory for Elementary-Particle Physics FAX: +1-607-255-8062
>LT105 R. R. Wilson Laboratory http://www.lepp.cornell.edu/~seb/
>Dryden Road Internet: SEB@LEPP.CORNELL.EDU
>Ithaca, NY, USA 14853-8001 HEPnet/SPAN: LNS62::SEB = 44284::SEB
--
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James Hammett
Users Services / Server and Lab Administration
(SLAM)
Information Technology Services ( (ITS) CPE 4.442
Chemical Engineering Unix Support 471-9701
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An injustice anywhere is a threat to justice everywhere - MLK jr.
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