11.3 Node Specific Policies
Node policies within Moab allow specification of not only how the node's load should be managed, but who can use the node, and how the node and jobs should respond to various events. These policies allow a site administrator to specify on a node by node basis what the node will and will not support. Node policies may be applied to specific nodes or applied system-wide using the specification NODECFG[DEFAULT] ....
11.3-A Node Usage/Throttling Policies
This policy constrains the number of total independent jobs a given node may run simultaneously. It can only be specified via the NODECFG parameter.
On Cray XT systems, use the NID (node id) instead of the node name. For more information, see Configuring the moab.cfg file.
Constrains the number of total independent jobs a given node may run simultaneously associated with any single user. It can only be specified via the NODECFG parameter.
Constrains the number of total independent jobs a given node may run simultaneously associated with any single group. It can only be specified via the NODECFG parameter.
MAXLOAD constrains the CPU load the node will support as opposed to the number of jobs. This maximum load policy can also be applied system wide using the parameter NODEMAXLOAD.
This policy constrains the number of total dedicated processor-equivalents a given node may support simultaneously. It can only be specified via the NODECFG parameter.
This policy constrains the number of total dedicated processors a given node may support simultaneously. It can only be specified via the NODECFG parameter.
This policy constrains the number of total processors a given node may have dedicated to any single user. It can only be specified via the NODECFG parameter.
This policy constrains the number of total processors a given node may have dedicated to any single group. It can only be specified via the NODECFG parameter.
Node throttling policies are used strictly as constraints. If a node is defined as having a single processor or the NODEACCESSPOLICY is set to SINGLETASK, and a MAXPROC policy of 4 is specified, Moab will not run more than one task per node. A node's configured processors must be specified so that multiple jobs may run and then the MAXJOB policy will be effective. The number of configured processors per node is specified on a resource manager specific basis. PBS, for example, allows this to be adjusted by setting the number of virtual processors with the np parameter for each node in the PBS nodes file.
Example 11-3:
NODECFG[node024] MAXJOB=4 MAXJOBPERUSER=2 NODECFG[node025] MAXJOB=2 NODECFG[node026] MAXJOBPERUSER=1 NODECFG[DEFAULT] MAXLOAD=2.5 ...
11.3-B Node Access Policies
While most sites require only a single cluster wide node access policy (commonly set using NODEACCESSPOLICY), it is possible to specify this policy on a node by node basis using the ACCESS attributes of the NODECFG parameter. This attribute may be set to any of the valid node access policy values listed in the Node Access Policies section.
Example 11-4:
To set a global policy of SINGLETASK on all nodes except nodes 13 and 14, use the following:
# by default, enforce dedicated node access on all nodes NODEACCESSPOLICY SINGLETASK # allow nodes 13 and 14 to be shared NODECFG[node13] ACCESS=SHARED NODECFG[node14] ACCESS=SHARED
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