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Table Of Contents
6 From the Type drop-down menu, select either Keep Virtual Machines Together or Separate Virtual
Machines.
7 Click Add.
8 Select at least two virtual machines to which the rule will apply and click OK.
9 Click OK.
VM-VM Anity Rule Conflicts
You can create and use multiple VM-VM affinity rules, however, this might lead to situations where the
rules conflict with one another.
If two VM-VM affinity rules are in conflict, you cannot enable both. For example, if one rule keeps two
virtual machines together and another rule keeps the same two virtual machines apart, you cannot enable
both rules. Select one of the rules to apply and disable or remove the conflicting rule.
When two VM-VM affinity rules conflict, the older one takes precedence and the newer rule is disabled.
DRS only tries to satisfy enabled rules and disabled rules are ignored. DRS gives higher precedence to
preventing violations of anti-affinity rules than violations of affinity rules.
VM-Host Anity Rules
A VM-Host affinity rule specifies whether or not the members of a selected virtual machine DRS group
can run on the members of a specific host DRS group.
Unlike a VM-VM affinity rule, which specifies affinity (or anti-affinity) between individual virtual machines, a
VM-Host affinity rule specifies an affinity relationship between a group of virtual machines and a group of
hosts. There are 'required' rules (designated by "must") and 'preferential' rules (designated by "should".)
A VM-Host affinity rule includes the following components.
n
One virtual machine DRS group.
n
One host DRS group.
n
A designation of whether the rule is a requirement ("must") or a preference ("should") and whether it
is affinity ("run on") or anti-affinity ("not run on").
Because VM-Host affinity rules are cluster-based, the virtual machines and hosts that are included in a
rule must all reside in the same cluster. If a virtual machine is removed from the cluster, it loses its DRS
group affiliation, even if it is later returned to the cluster.
Create a VM-Host Anity Rule
You can create VM-Host affinity rules to specify whether or not the members of a selected virtual machine
DRS group can run on the members of a specific host DRS group.
Prerequisites
Create the virtual machine and host DRS groups to which the VM-Host affinity rule applies.
vSphere Resource Management
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