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

Hearns, John john.hearns at mclaren.com
Mon Oct 26 13:01:16 EDT 2009


On Mon, Oct 26, 2009 at 11:34 AM, Bogdan Costescu <bcostescu at gmail.com>
wrote:
> On Mon, Oct 26, 2009 at 4:50 PM, Rahul Nabar <rpnabar at gmail.com>
wrote:

> The BMC is a CPU running some firmware. It's a low power one though,
> as it doesn't usually have to do too many things and it should not
> consume significant power while the main system is off. Some BMCs even
> run a ssh or http daemon to allow an easier interaction.

To me the additional services seem one of the root causes of problems.
Complexity just means more places for stuff to go wrong at. It may not
be super difficult to impliment ARP and IPMI but when you start adding
ssh and http you are pretty much writing some pretty complex daemons I
suppose.


On the original Opteron sun servers
which had BMCs and the two Ethernet interfaces which you could
daisy-chain,
the BMCs were Motorola single board computers running Linux.
So ssh and http access were already there with whichever Linux distro
they
ran (you could look around in /proc for instance)

http access was dead useful - I remember using it, and also on the
silver coloured 
xNNNN series which followed them. As I recall, it was a nice interface
to list the hardware
error logs.


Regarding how IPMI and eth0 co-exist on one interface, I though there
was 
a simple bridge chip on the motherboard.




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