VMware Cluster. DRS Configuration

In the previous post, we looked at the importance of utilizing the VMware vSphere ESXi cluster to unlock the true potential of what VMware ESXi can do in the enterprise. One of the key advantages with the VMware cluster configuration is the efficient management of resources. The vSphere cluster technology that makes this possible is VMware DRS or distributed resource scheduler.

VMware DRS is designed to manage a cluster’s available resources effectively and efficiently. DRS can proactively manage resources in the cluster so that the load between hosts is more evenly shared. Also, DRS rules can make sure that certain VMs or groups of VMs are always on different hosts or the same hosts. Also, new to vSphere 6.5, DRS can take network bandwidth into consideration when scheduling resources to prevent oversubscription. When a host is added to a DRS cluster, the host’s resources become part of the cluster’s resources and is managed accordingly. This allows for the use of cluster-level resource pools and resource allocation policies. Resource pools allow you to allocate resources according to your needs, policies, or VM requirements. Resource pools can allow some VMs to have access to more hardware resources and others less resources.

Requirements for DRS include the following:

  • Shared storage
  • Processor compatibility – since DRS utilizes vMotion, the vMotion process transfers the running CPU state between the various ESXi hosts, requiring that destination hosts have at least the equivalent CPU instruction capability
  • Hosts in the cluster must participate in a vMotion network

DRS Configuration

In the vSphere vCenter 6.5 Flash Web UI, the DRS and HA options are configured using the Configure tab of the cluster. Click vSphere DRS and then Edit.

VMware Cluster. DRS Configuration

We are presented with a simple checkbox where DRS can be enabled.

Turn on vSphere DRS

If we drill into the DRS settings a bit more, we can customize the behavior of DRS within our VMware cluster. The automation level can be selected to decide how much control DRS has over migrating resources.

VMware DRS automation

New to DRS in vSphere 6.5, there is a Predictive DRS that allows DRS to interact with vRealize Operations Manager to actually predict the moving around of VM resources based on vROPs.

Predictive DRS

After we select our DRS options, we can select OK and the VMware cluster will be configured for DRS.


VMware DRS technology allows efficient and effective resource management of multiple hosts in the vSphere cluster. As shown, the feature is easily enabled and is very intuitive to configure. The new features of vSphere 6.5 also allow the technology to be predictive and proactive. The other very important technology feature that is enabled with the vSphere cluster is VMware HA or high availability. In the next post we will take a look at this other key VMware vSphere cluster feature.