Resource Clusters

Group VMware® ESXi™ hosts into resource clusters to segregate the computing needs of different business units. VMware vSphere® clusters allow you to:

  • Provide highly available resources to your workloads.
  • Balance workloads for optimal performance.
  • Scale and manage computing resources without service disruption.

Balanced Capacity

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 and Enterprise Plus editions. Using DRS, you can:

  • Improve service levels by guaranteeing appropriate resources to virtual machines.
  • Deploy new capacity to a cluster without service disruption.
  • Automatically migrate virtual machines during maintenance without service disruption.
  • Monitor and manage more infrastructure per system administrator.

Reduced Energy Consumption

Optimize power consumption dynamically within a vSphere cluster with VMware vSphere® Distributed Power Management™ (DPM), also included in vSphere Enterprise and 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:

  • Cut power and cooling costs by as much as 20 percent during low utilization periods.
  • Automate energy management in your data center more efficiently.

Technical Details

Initial Workload Placement

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—VMware® vCenter™ will only apply recommendations that satisfy cluster constraints such as host affinity rules or maintenance—to aggressive—vCenter applies DRS recommendations that 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.

Automated Load Balancing

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.

Optimized Power Consumption

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. Should 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.

Cluster Maintenance

DRS speeds up 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.

Constraint Correction

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.