Unable to grow or expand a VMFS volume or datastore

VMware vSphere ESXi VMware vSphere ESXi 7.0 VMware vSphere ESXi 8.0

When trying to grow or expand a VMFS volume by clicking Increase Capacity, no drives are being displayed or not the desired drives are showing up.

VMware ESXi 7.x, 8.x and 9.x

Potential Causes preventing a successful grow/expansion of the VMFS volume or datastore:

To increase the capacity (grow or extend) of a VMFS datastore successfully, ensure that the device has been increased from the backend SAN.
Once completed, initiate a cluster level rescan to ensure that the Extent Device list contains updated list and then use the Increase option.
If the device for which size is increased from backend SAN is exposed to multiple hosts in multiple clusters, then cluster level rescan has to be triggered on all the clusters where device is visible.
Also ensure that the LUN ID is same across all the cluster hosts.
Please ensure there are no partition on the existing LUNS which are being added to the datastore.
If the datastore is local datastore, and unable to see the drive during the datastore expansion, refer New disk not visible when increasing local datastore capacity in ESXi

After the cause has been identified and resolved, the Capacity of a VMFS datastore can be expanded via the following ways:

Via vCenter Web Client:

Initiate a Cluster level rescan (incase the device is shared across multiple hosts/clusters) or on the host (incase of a stand-alone host) so as to force the ESXi host(s) to sync in with the change for the underlying devices expansion.
If the device for which size is increased from backend SAN is exposed to multiple hosts in multiple clusters, then rescan has to be triggered on all the hosts across the clusters where device is visible.

Navigate to Datastore and select Datastore > Click on Hosts > Select all the listed Hosts
Then Click on Actions > Rescan Storage

Navigate to Host and Cluster view > right Click on Cluster > Click on Storage > Click on Rescan Storage

Navigate to the Datastore View and select the Datastore
Navigate to Configure > Device Backing and select the Extent Name
You should be able to see the Device Details reflecting the update capacity basis the expansion done from the SAN.

Notes:

In this example, the datastore iscsi1 was configured for 250 GB and the underlying device was expanded to 400 GB.
If the underlying device is not reflecting the updated info, attempt a cluster/host level rescan once again so that the fields highlighted in the image above indicate the desired change.
If a Cluster level rescan is not done from the vCenter Server level, there are good chances that the vCenter Server might not readily detect the change
and there would be a disparity in the current space/usage for the datastore in question.
VMware recommends that a Cluster level rescan at the vCenter Server level is always followed after any form of expansion being done at the host level.