6.5.1

Creating a DRS Cluster 10
A cluster is a collection of ESXi hosts and associated virtual machines with shared resources and a shared
management interface. Before you can obtain the benets of cluster-level resource management you must
create a cluster and enable DRS.
Depending on whether or not Enhanced vMotion Compatibility (EVC) is enabled, DRS behaves dierently
when you use vSphere Fault Tolerance (vSphere FT) virtual machines in your cluster.
Table 10‑1. DRS Behavior with vSphere FT Virtual Machines and EVC
EVC DRS (Load Balancing) DRS (Initial Placement)
Enabled Enabled (Primary and Secondary VMs) Enabled (Primary and Secondary VMs)
Disabled Disabled (Primary and Secondary VMs) Disabled (Primary VMs)
Fully Automated (Secondary VMs)
This chapter includes the following topics:
n
“Admission Control and Initial Placement,” on page 63
n
“Virtual Machine Migration,” on page 65
n
“DRS Cluster Requirements,” on page 67
n
“Conguring DRS with Virtual Flash,” on page 68
n
“Create a Cluster,” on page 68
n
“Edit Cluster Seings,” on page 69
n
“Set a Custom Automation Level for a Virtual Machine,” on page 71
n
“Disable DRS,” on page 72
n
“Restore a Resource Pool Tree,” on page 72
Admission Control and Initial Placement
When you aempt to power on a single virtual machine or a group of virtual machines in a DRS-enabled
cluster, vCenter Server performs admission control. It checks that there are enough resources in the cluster
to support the virtual machine(s).
If the cluster does not have sucient resources to power on a single virtual machine, or any of the virtual
machines in a group power-on aempt, a message appears. Otherwise, for each virtual machine, DRS
generates a recommendation of a host on which to run the virtual machine and takes one of the following
actions
n
Automatically executes the placement recommendation.
VMware, Inc.
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