VMware vSphere is capable of load balancing virtual machines and providing high availability in the event a ESXi host goes down. In order to achieve this a DRS (load balancing) and HA (high availability) cluster needs to be created and ESXi hosts added to it. A prerequisite for DRS is to set-up vMotion on the networking side, which has been covered in a separate post. HA requires at least two datastores for the purposes of high availability.
The following article goes through the steps of creating a DRS and HA cluster and adding hosts to it.
Log on to the vSphere Web Client.
Click on Hosts and Clusters.
Click on the datacenter and click Create a cluster.
Enter the cluster name in Name and click Turn ON next to DRS.
For Automation Level select Fully automated, to allow vCenter server to migrate VM's to evenly distribute the workload. Partially automated where vCenter Server will decide, which host the VM will run on at power up, but will only make recommendations for migrating VM's. Manual only allows vCenter Server to make recommendations to the administrator for powering up a VM and the evenly distributing the workload across the hosts. The Migration Threshold specifies how agressively vCenter Server will pursue these performance gains.
Click Turn ON next to vSphere HA to enable automatic boot-up of virtual machines that were running on an ESXi host that has failed.
Enable host monitoring causes the ESXi hosts in the cluster to send heartbeat packets between them to show that the hosts are still up. This should remained selected, unless there is network maintenance being performed, which may cause the cluster to believe it has lost ESXi hosts.
The Policy can be set to Host failures cluster tolerates, which specifies the maximum number of hosts that can fail in the cluster before it runs out of resources. Percentage of cluster resources reserved as failover space capacity that specifies the maximum amount of CPU and memory resources that can be lost in a cluster.
VM Monitoring Status can be enabled to monitor the VM's themselves, so if they stop responding they can be reset and booted back up again automatically. This can be done at the cluster level for all VM's or indivdually.
The Recent Tasks window should show that the cluster was successfully created.
Drag-and-drop the ESXi host on to the cluster in the tree to add it to the cluster.
You will be prompted to either put all the VM's into the root of the cluster or create a new resource pool and place all the VM's in there.
The Recent Tasks should show that the ESXi host was successfully added to the cluster.
Drag-and-drop the other ESXi hosts into the cluster.
Specify where to place the VM's.
The cluster should now be created with, in this case, two ESXi hosts in it.