To enable SIOC on a datastore:

1. Log in to the vCenter Server using vSphere Web Client.
2. In the Datastores and Datastore Clusters inventory view, select a datastore and click on the Configure tab.
3. In the General section, click on Edit under Datastore Capabilities.
4. Click on Enable Storage I/O Control.
5. Click on the OK button.

To set the storage I/O shares and limits, carry out the following steps:

1. Right-click on the VM in the inventory and select Edit Settings.
2. In the Virtual Hardware tab, expand the drive where you want to set the shares or limits.

By default, all the VM shares are set to normal (1000) with unlimited IOPS.