When you need to create virtual machines on a datastore, or when the virtual machines running on a datastore require more space, you can dynamically increase the capacity of a VMFS datastore.

Use one of the following methods to increase a VMFS datastore:

  • Add a new extent. An extent is a partition on a storage device. You can add up to 32 extents of the same storage type to an existing VMFS datastore. The spanned VMFS datastore can use any or all of its extents at any time. It does not need to fill up a particular extent before using the next one.
  • Grow an extent in an existing VMFS datastore, so that it fills the available adjacent capacity. Only extents with free space immediately after them are expandable.
Note: If a shared datastore has powered on virtual machines and becomes 100% full, you can increase the datastore's capacity only from the host with which the powered on virtual machines are registered.


Launch the vSphere Client and log in to a vCenter Server system.

Required privilege: Host.Configuration.Storage Partition Configuration


  1. Log in to the vSphere Client and select a host from the Inventory panel.
  2. Click the Configuration tab and click Storage.
  3. From the Datastores view, select the datastore to increase and click Properties.
  4. Click Increase.
  5. Select a device from the list of storage devices and click Next.
    Option Description
    To add a new extent Select the device for which the Expandable column reads NO.
    To expand an existing extent Select the device for which the Expandable column reads YES
  6. Review the Current Disk Layout to see the available configurations and click Next.
  7. Select a configuration option from the bottom panel.
    Depending on the current layout of the disk and on your previous selections, the options you see might vary.
    Option Description
    Use free space to add new extent Adds the free space on this disk as a new extent.
    Use free space to expand existing extent Expands an existing extent to a required capacity.
    Use free space Deploys an extent in the remaining free space of the disk. This option is available only when you are adding an extent.
    Use all available partitions Dedicates the entire disk to a single extent. This option is available only when you are adding an extent and when the disk you are formatting is not blank. The disk is reformatted, and the datastores and any data that it contains are erased.
  8. Set the capacity for the extent.
    The minimum extent size is 1.3GB. By default, the entire free space on the storage device is available.
  9. Click Next.
  10. Review the proposed layout and the new configuration of your datastore, and click Finish.

What to do next

After you grow an extent in a shared VMFS datastore, refresh the datastore on each host that can access this datastore, so that the vSphere Client can display the correct datastore capacity for all hosts.