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Growing or expanding a VMFS volume or datastore (1017662)


When you try to grow or expand a VMFS volume, you experience these symptoms:

  • One or more storage devices are increased in capacity from the storage array
  • When you click Increase, there are no available devices to select
  • When you click Increase, a device is listed but does not have Expandable = Yes
  • When you select the volume and click Next, you see the error:

    failed to update disk partition information


This article provides the steps to increase the capacity (grow or extend) of a VMFS datastore successfully.

Note: Increasing the size of the backup storage device on the storage array is a prerequisite before modifying the size of the VMFS Datastore filesystem and is outside the scope of this article. VMware vSphere does not modify the size of a LUN or other storage device on the array. Modifying the size of an array device is done using the management tools of the storage array vendor. For more information, contact the storage array vendor.

Note: This method only works for non-Local non-Boot devices.

For more information on Local VMFS datastores, see:


To increase the capacity of a VMFS datastore:

  1. In vCenter Server, select the Datastores view.
  2. Select the datastore you want to grow and identify the host that has more virtual machines running on it.
  3. Open another vSphere client that connects directly to the ESX host.
  4. Go to Configuration > Storage adapters and perform a rescan. For more information, see Performing a rescan of the storage on an ESX/ESXi host (1003988).
  5. Go to Configuration > Storage, click the datastore that you want to grow, and click Properties.
  6. Ensure that the new size of the device is listed in the Extent Device list. If the increased size does not reflect, review the changes on the storage array and rescan again.
  7. Click Increase.
  8. Select a device from the list of storage devices for which the Expandable column is Yes and click Next.
  9. Set the capacity for the extent. The default capacity for the extent is the entire free space on the storage device.

    Note: VMware recommends you to use the default setting.

  10. Click Next.
  11. After the process completes, go to vCenter Server, right-click the cluster that sees the expanded datastore, and click Rescan for Datastores. For more information, see Performing a rescan of the storage on an ESX/ESXi host (1003988).
  12. If there are other hosts that see the expanded datastore, perform a rescan on these hosts also.

Note: If the LUN experiences a high I/O throughput when growing the VMFS, the ESX host is not able to complete the operation. In such a case, repeat the process during non-business hours and when backup operations are not running. If the problem persists, power off some of the virtual machines residing on the LUN and then retry.

Note: In case, After step 6 and/or 7, if you do not see the datastore, try performing the same steps by connecting to the stand alone ESXi host directly rather than from vCenter server.

For more information, see Adding an extent to a VMFS volume fails after increasing local storage space (1002821).

Additional Information

  • If a shared datastore powers on virtual machines and becomes 100% full, increase the datastores capacity only from the host on which the powered-on virtual machines are registered.
  • As an alternative workaround, free up additional storage space by performing a Storage vMotion to migrate some of the virtual machines to a datastore with more available space.


increase-datastore increase-size

See Also

Update History

07/13/2011 - Added note about increasing the size of storage arrays. 04/08/2013 - Added vCenter Server 5.1.x and ESXi 5.1.x to Products 04/24/2-13 - Added alternative workaround in the Additional Information section

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