Simple Load-balancing

[Reuben D. Budiardja]

Hi all,
I need some suggestions on how to do this, or some poimter in the right 
direction. I tried to STW, but most of the stuffs that I found is too 
involved or complicated, I think.

Here's the situation. I have a beowulf linux cluster that we primarilly use 
for parallel computing using MPI. Assume there are 4 nodes in cluster, called 
node1, node2, etc. Only node1 is can see the world, so from outside, people 
can only do 'ssh node1'. Then after that, they can go to any other nodes 
since the nodes are in a LAN. /home is NFS mounted across all nodes.

However, people also uses this cluster to run application, and executables 
that does not need parallel computing. The problem is, people would do 'ssh 
node1', then run X apps or executable there. This makes nodes1 the busiest 
nodes all the time, while other nodes idle (if there are no parallel job). 

What I'd like to do is to distribute this load automatically. Since all the 
nodes are homogenous, for most apps and executables it can be run in any 
nodes. This may not be so hard if that's all there is to it. The problem is, 
some program only exist and can be started from node1, ie. we have some 
compilers with only 1 license, thus only exist in node1, parallel job with 
mpi can only be started from the master node (node1).

So, how do I do:
1. If user just do 'ssh node1' from outside, the user will automatically be 
'transferred' to the most available node, so that the user run applications 
from that less busy node.

2. If this user really knows that the program s/he needs only exist in node1, 
or want to start parallel job, the user can do something like 
'ssh node1 -notransfer', or any other option so that for sure the user gets to 
node1.

Any suggestion? 

Thanks in advance
RDB
-- 
Reuben D. Budiardja
Dept. Physics and Astronomy
University of Tennesse, Knoxville, TN

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