VMware vSphere vCenter Server 4.0 - Manual (Page 37)

Managing Resource Pools
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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.
Each standalone host and each DRS cluster has an (invisible) root resource pool that groups the resources of
that host or cluster. The root resource pool is not displayed because the resources of the host (or cluster) and
the root resource pool are always the same.
Users can create child resource pools of the root resource pool or of any user-created child resource pool. Each
child resource pool owns some of the parent’s resources and can, in turn, have a hierarchy of child resource
pools to represent successively smaller units of computational capability.
A resource pool can contain child resource pools, virtual machines, or both. You can create a hierarchy of
shared resources. The resource pools at a higher level are called parent resource pools. Resource pools and
virtual machines that are at the same level are called siblings. The cluster itself represents the root resource
pool. If you do not create child resource pools, only the root resource pools exist.
In
Figure 4-1 , RP-QA is the parent resource pool for RP-QA-UI. RP-Marketing and RP-QA are siblings. The
three virtual machines immediately below RP-Marketing are also siblings.
Figure 4-1. Parents, Children, and Siblings in Resource Pool Hierarchy
root resource pool
siblings
siblings
parent resource pool
child resource pool
For each resource pool, you specify reservation, limit, shares, and whether the reservation should be
expandable. The resource pool resources are then available to child resource pools and virtual machines.
This chapter includes the following topics:
n “Why Use Resource Pools?,” on page 38
n “Create Resource Pools,” on page 39
n “Add Virtual Machines to a Resource Pool,” on page 40
n “Removing Virtual Machines from a Resource Pool,” on page 41
n “Resource Pool Admission Control,” on page 41
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