vSAN automatically rebalances data on the disks by default. You can configure settings for automatic rebalancing.

Your vSAN cluster can become unbalanced based on the space usage for many reasons such as when you create objects of different sizes, when you add new hosts or capacity devices, or when objects write different amounts of data to the disks. If the cluster becomes unbalanced, vSAN automatically rebalances the disks. Based on the space usage, this operation moves components from over-utilized disks to under-utilized disks.

You can enable or deactivate automatic rebalance, and configure the variance threshold for triggering an automatic rebalance. If any two disks in the cluster have a variance in capacity usage 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.

Procedure

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

What to do next

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