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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 have been 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) a VMFS datastore successfully.

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

Note: This method only works for non-Local non-Boot devices. For Local VMFS datastores, see Growing a local datastore from the command-line in vSphere ESX 4.x (1009125) or Growing a local datastore from the command line in vSphere ESXi 4.x and 5.x (2002461).


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 is not reflected, 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. 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 may not be 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.

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

Additional Information

  • If a shared datastore has powered on virtual machines and becomes 100% full, you can increase the datastores capacity only from the host on which the powered-on virtual machines are registered.
  • As an alternative work around, you can 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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