VMware vSphere vCenter Server 4.0 - Manual (Page 38)

Why Use Resource Pools?
Resource pools allow you to delegate control over resources of a host (or a cluster), but the benefits are evident
when you use resource pools to compartmentalize all resources in a cluster. Create multiple resource pools as
direct children of the host or cluster and configure them. You can then delegate control over the resource pools
to other individuals or organizations.
Using resource pools can result in the following benefits.
n Flexible hierarchical organization—Add, remove, or reorganize resource pools or change resource
allocations as needed.
n Isolation between pools, sharing within pools—Top-level administrators can make a pool of resources
available to a department-level administrator. Allocation changes that are internal to one departmental
resource pool do not unfairly affect other unrelated resource pools.
n Access control and delegation—When a top-level administrator makes a resource pool available to a
department-level administrator, that administrator can then perform all virtual machine creation and
management within the boundaries of the resources to which the resource pool is entitled by the current
shares, reservation, and limit settings. Delegation is usually done in conjunction with permissions settings.
n Separation of resources from hardware—If you are using clusters enabled for DRS, the resources of all
hosts are always assigned to the cluster. That means administrators can perform resource management
independently of the actual hosts that contribute to the resources. If you replace three 2GB hosts with two
3GB hosts, you do not need to make changes to your resource allocations.
This separation allows administrators to think more about aggregate computing capacity and less about
individual hosts.
n Management of sets of virtual machines running a multitier service— Group virtual machines for a
multitier service in a resource pool. You do not need to set resources on each virtual machine. Instead,
you can control the aggregate allocation of resources to the set of virtual machines by changing settings
on their enclosing resource pool.
For example, assume a host has a number of virtual machines. The marketing department uses three of the
virtual machines and the QA department uses two virtual machines. Because the QA department needs larger
amounts of CPU and memory, the administrator creates one resource pool for each group. The administrator
sets CPU Shares to High for the QA department pool and to Normal for the Marketing department pool so
that the QA department users can run automated tests. The second resource pool with fewer CPU and memory
resources is sufficient for the lighter load of the marketing staff. Whenever the QA department is not fully
using its allocation, the marketing department can use the available resources.
This scenario is shown in
Figure 4-2 . The numbers show the effective allocations to the resource pools.
Figure 4-2. Allocating Resources to Resource Pools
VM-QA 1 VM-QA 2
6GHz, 3GB
4GHz, 2GB 2GHz, 1GB RP-QA
VM-Marketing 1 VM-Marketing 2 VM-Marketing 3
RP-
Marketing
ESX/ESXi
host
vSphere Resource Management Guide
38 VMware, Inc.