When any capacity device in your cluster reaches 80 percent full, vSAN automatically rebalances the cluster.

The vSAN cluster rebalancing continues until the space available on all capacity devices is below the threshold. Cluster rebalancing evenly distributes resources across the cluster to maintain consistent performance and availability.

The following operations can cause disk capacity to reach 80% and initiate cluster rebalancing:
  • Hardware failures occur on the cluster.
  • vSAN hosts are placed in maintenance mode with the Evacuate all data option.
  • vSAN hosts are placed in maintenance mode with Ensure data accessibility when objects assigned FTT=0 reside on the host.
Note: To provide enough space for maintenance and reprotection, and to minimize automatic rebalancing events in the vSAN cluster, consider keeping 30-percent capacity available at all times.