6.0.1

Resource Consumers
Virtual machines are resource consumers.
The default resource settings assigned during creation work well for most machines. You can later edit the
virtual machine settings to allocate a share-based percentage of the total CPU, memory, and storage I/O of
the resource provider or a guaranteed reservation of CPU and memory. When you power on that virtual
machine, the server checks whether enough unreserved resources are available and allows power on only if
there are enough resources. This process is called admission control.
A resource pool is a logical abstraction for flexible management of resources. Resource pools can be grouped
into hierarchies and used to hierarchically partition available CPU and memory resources. Accordingly,
resource pools can be considered both resource providers and consumers. They provide resources to child
resource pools and virtual machines, but are also resource consumers because they consume their parents’
resources. See Chapter 9, “Managing Resource Pools,” on page 55.
ESXi hosts allocate each virtual machine a portion of the underlying hardware resources based on a number
of factors:
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Resource limits defined by the user.
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Total available resources for the ESXi host (or the cluster).
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Number of virtual machines powered on and resource usage by those virtual machines.
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Overhead required to manage the virtualization.
Goals of Resource Management
When managing your resources, you should be aware of what your goals are.
In addition to resolving resource overcommitment, resource management can help you accomplish the
following:
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Performance Isolation—prevent virtual machines from monopolizing resources and guarantee
predictable service rates.
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Efficient Utilization—exploit undercommitted resources and overcommit with graceful degradation.
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Easy Administration—control the relative importance of virtual machines, provide flexible dynamic
partitioning, and meet absolute service-level agreements.
vSphere Resource Management
12 VMware, Inc.