In vSphere 7+ and VCF-managed clusters, the vSphere Cluster Services (vCLS) VMs must remain powered on for DRS, cluster health, and policy enforcement to function. If the vCLS VMs cannot power on, no workloads---including new VMs---can be deployed to the cluster because vSphere considers the cluster unhealthy.

A common cause is insufficient resources (CPU/memory), datastore issues, or policy conflicts preventing vCLS VMs from starting. VMware provides Retreat Mode as a troubleshooting mechanism to temporarily disable vCLS, allowing the administrator to deploy VMs and correct underlying issues. Enabling retreat mode:

Removes vCLS from the cluster

Restores ability to deploy VMs

Allows remediation of storage/placement issues

Can later be disabled to restore DRS health

Option A (deleting resource pools) does not restore vCLS VM power state. Option B (disabling HA) does not affect vCLS behavior. Option D (setting DRS automation level) does not correct vCLS placement problems.