[Beowulf] Infiniband Subnet Manager

Nifty niftyompi Mitch niftyompi at niftyegg.com
Thu Sep 4 15:16:36 PDT 2008

On Thu, Sep 04, 2008 at 02:37:23PM -0400, Prentice Bisbal wrote:
> Prentice Bisbal wrote:
> > Since an infiniband fabric needs a subnet mananger, should the master
> > node have an IB HCA and be connected to the IB network in order to run
> > the subnet manager?
> > 
> > My logic behind this is that the master node will be full
> > enterprise-level hardware (redundant every thing), and should never go
> > down or be rebooted during normal use. I expect the nodes to go down
> > more frequently (not fully redundant hardware, higher operating loads,
> > etc.).
> > 
> > Exactly what functions does the subnet manager perform, and what happens
> > if it disappears from the IB fabric?
> > 
> > I've been doing research into IB all day yesterday, and I'm continuing
> > today, so please no RTFM answers.
> > 
> I've gotten a lot of response to my IB questions that I posed to the
> list. Thanks for all your help. All of my questions have been answered.
> It turns out, as some as you pointed out, that my switch will have a
> built-in subnet manager, so I won't need to run one on a node.

I should add that a built in subnet manager is extra $$.  Also they tend
to run on a modest dedicated processor card.  The modest dedicated card
solutions have limited RAM and will not support a gonzo big fabric.
A rule of thumb, depending on the subnet manager on the card the run out of memory
recources trip point is about 144 ports.

The richer the statistics gathered and retained the larger the footprint is.

Large fabrics will need a host based subnet manager.

	T o m  M i t c h e l l 
	Got a great hat... now what.

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