[Beowulf] Re: Geriatric computer does not stay up

Gus Correa gus at ldeo.columbia.edu
Thu Dec 17 11:39:48 PST 2009

Hi David

There is more than one version of this motherboard,
hence I may be dead wrong about yours.

In any case, I have the mobo user manual here.
You can download it from Tyan also (with an appendix):


The manual says that jumper J86 disables/enables
the onboard "LAN" (3Com 3C905c).
Onboard Ethernet is *disabled* when the jumper is *closed*.
(It is probably open now, no jumper,
assuming onboard Ethernet is currently enabled.)

J86 is next to the motherboard edge, near PCI slot #4,
probably near the back of the node case.

Also, it is unclear whether PXE boot will work with a PCI NIC,
but it may.

Gus Correa
Gustavo Correa
Lamont-Doherty Earth Observatory - Columbia University
Palisades, NY, 10964-8000 - USA

David Mathog wrote:
> Gus Correa <gus at ldeo.columbia.edu> wrote
>> Some of the built-in 3Com Ethernet 100 interfaces on
>> Tyan S2466[-4M] motherboards we have here became flaky/failed
>> after many years of use.
>> Those are main boards in in several standalone workstations/PCs.
>> I don't administer those systems, but I believe the symptoms
>> were somewhat random, as those you describe.
>> Disabling the onboard Ethernet (by jumper), and replacing them by
>> PCI Ethernet 100 cards, gave those systems additional lifetime.
>> Would this be the case of your cluster node?
> Tyan S2466 MPX does not seem to have such a jumper.  Possibly it can be
> disabled in the BIOS. Oddly, the system is fine PXE booting over that
> interface, but every attempt at:
>   service network start
> hangs instantly.  Tried booting with a serial console like this from
> pxelinux.cfg:
> LABEL serial
>   KERNEL vmlinuz-
>   APPEND initrd=initrd- root=/dev/hda3 failsafe
>  console=ttyS0,38400
> which uses the initrd and vmlinuz downloaded from the server, and the
> disk from the iffy machine for the programs.  That booted fine, but the
> kernel emitted nothing on the serial line when the machine hung.
> Running smartctl now, after that will boot a rescue linux and see if
> that too has network issues.  
> Ran memory tests for over 20 hours without a single hiccup.
> I'll keep looking.  Thanks all.
> David Mathog
> mathog at caltech.edu
> Manager, Sequence Analysis Facility, Biology Division, Caltech
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