Summary: How to grow a VMWF datastore.
Date: Around 2012
Refactor: 1 March 2025: Checked links and formatting.

With the introduction of vSphere 4 VMware introduced an extra way for increasing the size of VMFS datastores. In previous versions you could add extra extents to increase the size, since vSphere 4 there is also the option available to just grow the datastore. There is one catch though, the space should be adjacent to the current datastore. Of course that is usually not the case but in our environment the storage is on a SAN from NetApp which uses WAFL, which never uses adjacent space in the first place, but tells that to the SAN clients anyway. So increasing the size of a VMFS datastore with NetApp SAN storage has become really easy:

The first step we have to do is to increase the available space on the LUN where the datastore resides. Open filerview and expand the Volumes section to manage the volumes which show a list. Simply click on the volume you want to increase:

This will show you the volume properties and an option to resize the storage:

This will start a small wizard in which you can enter the new size. When done expand the LUNs section and click the manage LUNs link. This will show you a list of available LUNs and again, simply click on the LUN you want to increase:

This will show you the current LUN properties which can be changes immediately:

A warning will be shown, indicating you should have installed the host utilities on the clients:

When done another informational message will be shown, which can be ignored:

Now the volume and LUN are increased, so now it's time to change the VMFS datastore.

In vCenter, select a host with access to the current datastore and to to the configuration tab and select the storage section. After clicking on the 'devices' view you can see the LUN you increased. Note that the new size is not yet visible. You can click refresh (or rescan All) after which the new size of the LUN is visible:

Then click on the 'datastores' view and click Properties:

This will show you the properties of the datastore and gives you an option to increase the size:

After clicking the increase option you'll be shown a wizard. In the first window you should select the current device the datastore resides on. Selecting another device will add an extent which is not what we want. My LUN has lunid 201 so select that one and click next:

In the next window you are shown what will be done regarding to the current layout. As you can see the free space is gonna be used to expand the VMFS volume:

Select here how much of the newly added space will be used:

Review all options and if you're sure this is what you want click finish:

Now you can see the increased capacity and that it's still one extent:

The increased capacity also shows in the 'Datastores' view:

Now the datastore has grown you can move VMs to it using Storage vMotion.