6.0

Disabling admission control allows a virtual machine to be powered on even if it causes insufficient
failover capacity. When this happens, no warnings are presented, and the cluster does not turn red.
If a cluster has insufficient failover capacity, vSphere HA can still perform failovers and it uses the
VM Restart Priority setting to determine which virtual machines to power on first.
NOTE Select this option to power on more virtual machines than the vSphere HA failover level can
support. If you select this option, failover is no longer guaranteed.
6 Select an admission control policy to apply to the cluster.
Option Description
Host failures the cluster tolerates
Select the maximum number of host failures that you can recover from or
to guarantee failover for.
Percentage of cluster resources
reserved as failover spare capacity
Specify a percentage of the cluster’s CPU and Memory resources to reserve
as spare capacity to support failovers.
Specify failover hosts
Click to select hosts to use for failover actions. Failovers can still occur to
other hosts in the cluster if a default failover host does not have enough
resources.
7 (Optional) Select Advanced Options to configure automation mode options.
Change these settings only when instructed to do so by VMware technical support or when you are
following specific instructions in VMware documentation.
8 Click OK.
Specify Failover Hosts
When you select the Specify Failover Hosts admission control policy, you must also designate which hosts
are to be used for this function.
Prerequisites
Launch the vSphere Client and log in to a vCenter Server system.
Procedure
1 Open the Specify Failover Hosts dialog box from the vSphere HA screen of the Cluster Settings dialog
box of the vSphere Client.
2 In the Available Hosts pane, select an available host to designate as a failover host.
3 Click the >> button to move the host name to the Failover Hosts pane.
4 Repeat steps 1 and 2 for each host you want to designate as a failover host.
5 To remove a host from the failover hosts list, select the name of that host in the Failover Hosts pane.
6 Click the << button to move the host name to the Available Hosts pane.
You can use the hosts designated as failover hosts to support the vSphere HA admission control process.
Set Virtual Machine Options
If you have enabled vSphere HA for a cluster, you can set the restart priority and host isolation response for
virtual machines in the cluster.
The Virtual Machine Options page appears only if you enabled vSphere HA.
Prerequisites
Launch the vSphere Client and log in to a vCenter Server system.
Chapter 26 Creating and Using vSphere HA Clusters
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