vSAN automatically rebalances data on the disk groups by default. You can configure settings for automatic rebalancing.
Your vSAN cluster can become unbalanced due to uneven I/O patterns to devices, or when you add hosts or capacity devices. If the cluster becomes unbalanced, vSAN automatically rebalances the disks. This operation moves components from over-utilized disks to under-utilized disks.
You can enable or disable automatic rebalance, and configure the variance threshold for triggering an automatic rebalance. If any two disks in the cluster have a capacity variance that meets the rebalancing threshold, vSAN begins rebalancing the cluster.
Disk rebalancing can impact the I/O performance of your vSAN cluster. To avoid this performance impact, you can turn off automatic rebalance when peak performance is required.
