[Beowulf] using two separate networks for different data streams

Douglas Eadline deadline at clustermonkey.net
Thu Jan 26 16:35:22 EST 2006


Obviously two network interfaces are needed per node for this
to work. Most motherboards now come with two Ethernet interfaces so this
has become a more standard way of doing things.

The way it is done is as follows. You setup two networks.
For example, your /etc/hosts file looks something like:

#compute network 192.168.0
192.168.0.1    node1-compute
192.168.0.2    node2-compute
...
192.168.0.128    master-compute

#admin network 192.168.1
192.168.1.1    node1-admin
192.168.1.2    node2-admin
...
192.168.1.128    master-admin

Where node1-compute and node1-admin are the same physical node, etc.

When you mount NFS in the /etc/fstab you do it over the *-admin network.
When you run an MPI job your node list is made of *-compute
node names.

It is often easier to use a cluster distribution to do this. Doing it by hand
can be tedious and error prone)

If you take a look at:

http://www.clustermonkey.net//content/view/43/29/

you can see how we did it using warewulf (quite easy).

--
Doug

>
> Hi
>
>   I've looked around, in the list and google and didn't find anything
> elucidating enough on this so mabe someone could englight me or point me
> where to look.
>
>   I've seen architectures with two network switchs, one is used for I/O
> (writing, reading, so on) and another for message passing (MPI). how is
> this achieved? I get the idea, from one place, where the applications
> running must be aware of this but I was thinking that for this to work it
> must be transparent to the application. How can this be achieved?
>
>   Any thought will be appreciated.
>
>   best regards,
>
>   Ricardo Reis
>
>   "Non Serviam"
>
>   n.p.: http://radio.ist.utl.pt
>   n.r.: http://atumtenorio.blogspot.com
>                      <- Send with Pine Linux/Unix/Win/Mac OS->
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-- 
Doug
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