[torqueusers] random node selection using maui?

David B Jackson jacksond at clusterresources.com
Thu Feb 8 20:01:49 MST 2007

Pete, Lennart,

  Moab provides a 'random' factor to the 'priority' node allocation
policy.  Using the random node allocation factor weight, this random
factor can completely dominate or be merged with other factors to get
the desired weighting.  Currently, this node allocation policy is
global, but in later versions, these weighting factors can be per queue
or per job.

  This feature may be useful in this case.


> Hi Lennart,
> the randomization goal is to have the computation on as many different
> physical racks as possible.  This is for data locality (i.e., latency)
> and IO bandwidth scaling for a distributed file system.
> The other way we are looking at is, just like you proposed, having a
> node property called rackid-XXXX where XXXX = the subnet and then when
> doing qsubs, requesting N/#racks of each rack type as a scheduling
> preference.
> I was thinking that if there were a way to be completely random (pseudo
> random :)), we could get the same effect.
> pete
> Lennart Karlsson wrote:
>> wyckoff at yahoo-inc.com said:
>>> I have a largish cluster (~3K nodes) and I want the ability to
>>> allocate  a random N nodes on the cluster.  The maui documentation
>>> says that  FASTEST allocation with no attributes is random, but it
>>> isn't.  Is there  another way to do this?
>> Peter,
>> As far as I know, you have to do the randomization yourself. The first
>> three ways that comes to my mind is:
>> 1/ Change the Maui code to add a randomization parameter. The hard way.
>> 2/ Stop Maui, stop Torque, randomize the node ordering in the Torque
>> configuration file "nodes", start Torque, and start Maui, in that
>> sequence. A lot of restarts of the applications so it is not at all
>> practical if you need to do it more than a few times. But you have not
>> told us why you want the randomization: If you actually just want to
>> schedule the nodes in a different order, you can reorder the "nodes"
>> file once in whatever way you want and be happy ever after. :-)
>> 3/ Choose a number of random node names from your cluster and give
>> those node names as qsub parameters, e.g.
>> 	qsub -l nodes=n125+n2836+n1583 scriptfile
>> Best wishes,
>> -- Lennart Karlsson <Lennart.Karlsson at nsc.liu.se>
>>    National Supercomputer Centre in Linkoping, Sweden
>>    http://www.nsc.liu.se
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