Unisphere for PowerMax: Unable to Extend VMFS Datastore on Expanded SRDF Device Pair

When using a PowerMax or VMAX All Flash array, there is the ability to dynamically expand SRDF device pairs. VMware permits extending an existing VMFS partition (datastore) onto the new space created by expanding that RDF device. Expanding a datastore with SRDF has the following steps:

1. Expand the SRDF device pair through Unisphere or Solutions Enabler.
2. Rescan the ESXi hosts where the device is presented and the datastore exists.
3. Run the UI vCenter wizard to expand the datastore.
4. VMware recognizes the new space, and the datastore is expanded.

VMware does not recognize that the datastore can be extended when using vSphere 6.7 vCenter. VMware displays no devices in the wizard, and the datastore cannot be extended, though it does recognize the newer size.

The cause is that VMware filters out the device in the wizard rather than including it. This is a VMware issue which exists on all vSphere platforms. Information in this issue can be found in VMware article Extending or increasing a datastore through vCenter Server fails

To bypass the issue, instead of using the vCenter to extend the datastore through a browser, log in directly to the ESXi host itself. Running the extension wizard through the ESXi client UI does not filter out the device, and the extension is successful. The other ESXi hosts in the cluster immediately recognize the change. This process is explained in the TechBook Using Dell VMAX and PowerMax in VMware vSphere Environments.

Run the procedure on the ESXi browser and not on vCenter:

1. Log in to the Primary ESXi Server.
2. Launch the vSphere web client by opening a web browser and logging into your Primary ESXi Server.
3. Select the Storage tab in the navigator panel.
4. Go to Adapters and select Rescan.
5. Check the Recent Tasks area at the bottom of the screen to ensure that the Rescan completes.
6. Select the Datastores tab.
7. Click Increase Capacity.
8. When the Increase datastore capacity window is open, select Expand an existing VMFS datastore extent, then click Next.
9. In the Select Device page, you should see that the original volume now has free space the same size as the original volume. Select the Volume and click Next.
10. The Partition options are unavailable. Select the blue partition in the Before section, and the After section should all turn blue. Click Next to continue.
11. After reviewing the settings in the Ready to complete page, click Finish.