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Notes:
► The PLM server may reside either in a partition on the same server as the
partitions being managed or on a different machine. When the PLM server
runs in a partition, it is capable of managing its own partition.
► Multiple Partition Load Manager servers may be run on one AIX 5L
system.
► Different PLM groups on a given server may be managed by different PLM
servers.
► A partition can have, at most, one PLM manager.
► It is not required that all partitions in a system be managed.
► One Partition Load Manager server can manage partitions within only one
managed CEC.
► It is not possible to have shared-processor and dedicated-processor
partitions in the same PLM partition group.
► Resources are constrained to a group: A partition in one PLM group will
never be given resources from another partition in another group.
► There should be at least two active partitions in a partition group.
Since each partition is monitored locally and the agents only communicate with
the PLM server when an event occurs, PLM consumes a negligible amount of
system and network resources.
6.1.3 Resource management policies
The resource management policy for each partition group is specified in a policy
file that defines both the managed environment and the parameters of the
resource management policy. The details of PLM policies are discussed in 6.2.5,
“Define partition groups and policies” on page 389.
The different partition states and load thresholds are shown in Figure 6-2 on
page 375. For each resource, there is an upper and lower load threshold. Every
time a threshold is crossed, PLM receives a Resource Management and Control
(RMC) event. When the load on the resource is above the upper threshold, the
partition PLM considers the partition in need of additional resources; the partition
is said to be a requestor. When the load on the resource is below the lower
threshold, the partition becomes a potential donor. Normally, resources are only
removed from donors when another partition enters the requestor state for the
same resource. When the load on the resource is between the two thresholds,
PLM considers that the resources available are adequate.
374 <strong>Advanced</strong> <strong>POWER</strong> <strong>Virtualization</strong> on IBM System p5