TopicVMware →
Simple definition
DRS automatically distributes, or recommends the distribution of, virtual machines across hosts in a vSphere cluster.
Technical definition
Distributed Resource Scheduler evaluates CPU and memory demand in a vSphere cluster and can recommend or trigger vMotion migrations to improve resource balance, depending on the configured automation level.
What is it used for?
Balance workload across VMware hosts while respecting cluster constraints and affinity or anti-affinity rules.
Practical example
When one ESXi host becomes heavily loaded, DRS can recommend or perform a vMotion migration of a VM to a host with more available capacity.
Common issues
- vMotion is unavailable or misconfigured
- Affinity or anti-affinity rules conflict with placement
- Cluster has insufficient spare capacity
Key takeaway: DRS optimizes placement inside a vSphere cluster; it depends on available resources and valid migration constraints.