[Beowulf] Re: question for licensed software users

Andrew Robbie andrew.robbie at gmail.com
Tue Jun 26 10:50:09 EDT 2007


On 26/06/2007, at 2:57 AM, Daniel Pfenniger wrote:

> Hi,
>
> I encountered also a NIC problem with Maple flexlm.  Flexlm checks
> the existence of the original eth0 NIC present at Maple install time.
> This interface was later bad, so a second one was added and
> used instead of eth0.  But then Maple was then prevented to start by
> flexlm.  After some search it was found that after each reboot one has
> to initialize eth0 once (ifconfig eth0 ... up), even if disabled later
> in order to satisfy flexlm.

It is possible under linux (and sometimes windows depending on the  
driver) to tell a card to use a different MAC address. If you are  
throwing out a bad NIC (ie two nodes with the same MAC will never  
appear on the network) this is a possible solution. It has to be done  
at every reboot, but that is easily accomplished by creating a  
startup script (or using rc.local). man ifconfig.

> No need to say that the lost time finding the cause of flexlm  
> disfunction
> was yet another argument to hate licensed software.

Talk to your vendor. The more people who complain the better.

Andrew


>
> 	Dan
>
>
> David Mathog wrote:
>>> I have had eth0 and eth1 "change" identities as I patch the OS or  
>>> add
>>> ethernet cards.
>>
>> Recent versions of Linux, such as Mandriva 2007.1, have an /etc/iftab
>> and/or /etc/udev/rules.d/61-net_config.rules files.  Both of these
>> associate one specific MAC with eth0, eth1, etc..
>> The original intent was noble - they were trying to provide a
>> way to allow eth0 to always be the wired and eth1 the wireless
>> network connection, for instance.  However if these files
>> get the least bit out of sync with the actual hardware
>> all hell can break loose.  For instance, if one clones a single NIC
>> machine that uses these mechanisms the MAC won't match, eth0 won't be
>> used and a new eth1 will be magically created.  Unfortunately
>> the firewall doesn't know about eth1 and everything network
>> related then breaks.  Result, most likely the machine will hang
>> during boot.  Others have reported machines which create a new
>> eth# device at each boot, abandoning all the previous ones.  The  
>> general
>> fix for these sorts of bugs is to delete both of these files, and
>> at the next boot the udev file will be recreated and will match the
>> hardware.  I have not seen a need for /etc/iftab and just leave it  
>> deleted.
>>
>> Now, back to Joe's problem, for the linux machines that are having
>> flexlm problems, if the nature of the problem is that eth0 and eth1
>> are swapping around at random, and those distros have these  
>> mechanisms,
>> be sure these two files exist and are configured properly so that
>> eth0 and eth1 are rigidly mapped to fixed MAC addresses.
>>
>> Regards,
>>
>> David Mathog
>> mathog at caltech.edu
>> Manager, Sequence Analysis Facility, Biology Division, Caltech
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