For ESXi hosts in a cluster, the remediation process can run either in a sequence or in parallel. Certain features might cause remediation failure. If you have VMware DPM, HA admission control, or Fault Tolerance enabled, you should temporarily disable these features to make sure that the remediation is successful.
Remediating hosts in parallel can improve performance significantly by reducing the time required for cluster remediation. Update Manager remediates hosts in parallel without disrupting the cluster resource constraints set by DRS. Avoid remediating hosts in parallel if the hosts are part of a vSAN cluster. Due to the specifics of the vSAN cluster, a host cannot enter maintenance mode while other hosts in the cluster are currently in maintenance mode.
- In the Home view of the vSphere Web Client, select the Update Manager icon.
- From the Objects tab, select an Update Manager instance.
The Objects tab also displays all the vCenter Server system to which an Update Manager instance is connected.
- Click the Manage tab.
- Click Settings, and select Host/Cluster Settings.
- Click Edit.
The Edit Host/Cluster Settings dialog box opens.
- Under Cluster Settings, select the check boxes for options that you want to disable or enable.
Distributed Power Management (DPM)
VMware DPM monitors the resource use of the running virtual machines in the cluster. If sufficient excess capacity exists, VMware DPM recommends moving virtual machines to other hosts in the cluster and placing the original host into standby mode to conserve power. If the capacity is insufficient, VMware DPM might recommend returning standby hosts to a powered-on state.
If you do not choose to disable DPM, Update Manager skips the cluster on which VMware DPM is enabled. If you choose to temporarily disable VMware DPM, Update Manager disables DPM on the cluster, remediates the hosts in the cluster, and re-enables VMware DPM after remediation is complete.
High Availability (HA) admission control
Admission control is a policy used by VMware HA to ensure failover capacity within a cluster. If HA admission control is enabled during remediation, the virtual machines within a cluster might not migrate with vMotion.
If you do not choose to disable HA admission control, Update Manager skips the cluster on which HA admission control is enabled. If you choose to temporarily disable HA admission control, Update Manager disables HA admission control, remediates the cluster, and re-enables HA admission control after remediation is complete.
Fault Tolerance (FT)
FT provides continuous availability for virtual machines by automatically creating and maintaining a secondary virtual machine that is identical to the primary virtual machine. If you do not choose to turn off FT for the virtual machines on a host, Update Manager does not remediate that host.
Enable parallel remediation for hosts in cluster
Update Manager can remediate hosts in clusters in a parallel manner. Update Manager continuously evaluates the maximum number of hosts it can remediate in parallel without disrupting DRS settings. If you do not select the option, Update Manager remediates the hosts in a cluster sequentially.
By design only one host from a vSAN cluster can be in a maintenance mode at any time. Update Manager remediates hosts that are part of a vSAN cluster sequentially even if you select the option to remediate them in parallel.
Migrate powered off and suspended virtual machines to other hosts in the cluster, if a host must enter maintenance mode
Update Manager migrates the suspended and powered off virtual machines from hosts that must enter maintenance mode to other hosts in the cluster. You can select to power off or suspend virtual machines before remediation in the Maintenance Mode Settings pane.
- Click OK.
These settings become the default failure response settings. You can specify different settings when you configure individual remediation tasks.