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<h1>5.4 Node Availability Policies</h1>

<p> Schedulers will allow jobs to be launched on a given
compute node as long as the node is not full or <i>busy</i>. The parameter
<b><a href="a.fparameters.php#nodeavailabilitypolicy">NODEAVAILABILITYPOLICY</a>
 </b>allows a site to determine what criteria constitutes a node being busy
. The legal settings are listed in the table below:</p>
<table cellpadding="2" cellspacing="2" border="1" width="100%">
  <tbody>
    <tr>
      <td valign="Top"><b>Availability Policy</b><br>
      </td>
      <td valign="Top"><b>Description</b><br>
      </td>
    </tr>
    <tr>
      <td valign="Top"><b>DEDICATED</b><br>
      </td>
      <td valign="Top">The node is considered busy if dedicated resources
equal or exceed configured resources<br>
      </td>
    </tr>
    <tr>
      <td valign="Top"><b>UTILIZED</b><br>
      </td>
      <td valign="Top">The node is considered busy if utilized resources
equal or exceed configured resources<br>
      </td>
    </tr>
    <tr>
      <td valign="Top"><b>COMBINED</b><br>
      </td>
      <td valign="Top">The node is considered busy if either dedicated or
utilized resources equal or exceed configured resources<br>
      </td>
    </tr>
  </tbody>
</table>
<p> The default setting for all nodes is <b>COMBINED</b>
 indicating that a node can accept workload so long as the jobs which the
node was allocated to do not request or utilize more resources than the node
has available. In a load balancing environment, this may not be the
desired behavior. Setting the <b>NODEAVAILABILITYPOLICY</b> parameter
to <b>UTILIZED</b> will allow jobs to be packed onto a node even if the aggregate
resources requested exceeds the resources configured. For example,
assume a scenario with a 4 processor compute node and 8 jobs requesting 1
processor each. If the resource availability policy was set to <b>COMBINED</b>
, this node would only allow 4 jobs to start on this node even if the jobs
induced a load of less than 1.0 each. With the resource availability
policy set to <b>UTILIZED</b>, the scheduler would continue to allow jobs
to be started on the node until the node's load average exceeded a per processor
load value of 1.0 (in this case, a total load of 4.0). To prevent a
node from being over populated within a single scheduling iteration, Maui
will artificially raise the node's load for one scheduling iteration when
starting a new job. On subsequent iterations, the actual measured node
load information will be used.</p>

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