Group VMware ESXi hosts into resource clusters to segregate the computing needs of different business units. VMware vSphere clusters allow you to:
VMware vSphere Distributed Resources Scheduler Diagram
Balance computing capacity by cluster to deliver optimized performance for hosts and virtual machines. VMware vSphere Distributed Resource Scheduler (DRS) is a feature included in the vSphere Enterprise Plus. Using DRS, you can:
Optimize power consumption dynamically within a vSphere cluster with VMware vSphere Distributed Power Management (DPM), which is also included in vSphere Enterprise Plus and vSphere with Operation Management Enterprise Plus editions. When demand for resources is low, DPM places hosts in standby mode and when demand is high, DPM powers on enough hosts to manage that demand and keep your services available. Dynamic power management with DPM allows you to:
When you power on a virtual machine in a cluster, DRS places it on an appropriate host or generates a recommendation, depending on the automation level you choose. Automation levels, also known as migration thresholds, range from conservative to aggressive. VMware vCenter will only apply recommendations that satisfy cluster constraints such as host affinity rules or maintenance. It applies DRS recommendations that can provide even a slight improvement to the cluster’s overall load balance. DRS offers five automation levels to fit your needs on a per cluster basis.
DRS spreads the virtual machine workloads across vSphere hosts inside a cluster and monitors available resources for you. Based on your automation level, DRS will migrate (VMware vSphere vMotion) virtual machines to other hosts within the cluster to maximize performance.
Like DRS, vSphere’s Distributed Power Management feature optimizes power consumption at the cluster and host level. When you enable DPM, it compares cluster- and host-level capacity to virtual machine demand, including recent historical demand, and places hosts in standby mode. If capacity demands increase, DPM powers on hosts in standby to absorb the additional workload. You can also set DPM to issue recommendations but take no actions.
DRS accelerates the VMware vSphere Update Manager remediation process by determining the optimum number of hosts that can enter maintenance mode simultaneously, based on current cluster conditions and demands.
DRS redistributes virtual machines across vSphere cluster hosts to comply with user-defined affinity and anti-affinity rules following host failures or during maintenance operations.