VMware vSphere vCenter Server 4.0 - Manual (Page 53)

Using DRS Clusters to Manage
Resources
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After you create a DRS cluster, you can customize it and use it to manage resources.
To customize your DRS cluster and the resources it contains you can configure DRS rules and you can add and
remove hosts and virtual machines. When a cluster’s settings and resources have been defined, you should
ensure that it is and remains a valid cluster. You can also use a valid DRS cluster to manage power resources
and interoperate with VMware HA.
This chapter includes the following topics:
n “Using DRS Rules,” on page 53
n “Adding Hosts to a Cluster,” on page 55
n “Adding Virtual Machines to a Cluster,” on page 56
n “Remove Hosts from a Cluster,” on page 56
n “Removing Virtual Machines from a Cluster,” on page 57
n “DRS Cluster Validity,” on page 58
n “Managing Power Resources,” on page 62
Using DRS Rules
You can control the placement of virtual machines on hosts within a cluster, by using DRS affinity and anti-
affinity rules. An affinity rule specifies that two or more virtual machines be placed on the same host. An anti-
affinity rule is limited to two virtual machines, and it requires that these two virtual machines not be placed
on the same host.
If two rules conflict, the older one will take precedence, and the newer rule is disabled. DRS only tries to satisfy
enabled rules, even if they are in violation. Disabled rules are ignored. DRS gives higher precedence to
preventing violations of anti-affinity rules than violations of affinity rules.
To check if any enabled DRS rules are being violated, select the cluster in the inventory panel of the vSphere
Client, select the DRS tab, and click Faults. Any rule currently being violated has a corresponding fault on this
page. Read the fault to determine why DRS is not able to satisfy the particular rule.
N
OTE
DRS rules are different from an individual host’s CPU affinity rules.
Create DRS Rules
You can create DRS rules to specify virtual machine affinity or anti-affinity.
Procedure
1 Select the cluster in the vSphere Client inventory.
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