[Beowulf] any creative ways to crash Linux?: does a shared NIC IMPI always remain responsive?

Gerald Creager gerry.creager at tamu.edu
Mon Oct 26 18:34:47 EDT 2009


Mark Hahn wrote:
>> IPMI gets hung sometimes (like Gerry says in his reply). I guess I can
>> just attribute that to bad firmware coding in the BMC.
> 
> I think it's better to think of it as a piece of hw (the nic)
> trying to be managed by two different OSs: host and BMC.
> it's surprising that it works at all, since there's no real
> standard for sharing the hardware.  I think all this adds up to a good 
> argument for non-shared nics.  (that doesn't necessitate
> a completely separate BMC-only fabric of switches, though.)


Great in theory, and mostly in practice, but the one I was specifically 
referencing which lost its mind, was not sharing a NIC, or at least, not 
directly.

<rant>
As Mark says, there's not a good, standard, way to share a NIC.  Folks 
(read, managers and vendors) who think this is a good idea usually don't 
have to fight the results of their musings.  They leave it to someone 
like me (or, for that matter, most of the folks reading this list) to 
figure out with hints and dribs of information, make sense of it, and 
fix.  THEY think it's cool to have eliminated another network.  THEY 
don't have to trace the thing back, but instead, look at their bottom 
line and tell us how much they did to improve our lives.  I've gotten to 
where I'd rather not use IPMI than to share a network between IPMI and 
"normal" network traffic.  And that's assuming we're talking about a 
private network that's safely isolated from folks who'd do you ill. 
I'll not go into my initial thoughts about someone who'd expose a suite 
of IPMI hosts to a public network.
</rant>

gerry
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