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.


  1. Navigate to the vSAN cluster.
  2. Click the Configure tab.
  3. Under vSAN, select Services.
  4. Click to edit Advanced Options.
  5. Click to enable or disable Automatic Rebalance.
    You can change the variance threshold to any percentage from 20 to 75.

What to do next

You can use the vSAN health service to check the disk balance. Expand the Cluster category, and select vSAN Disk Balance.