VMware vSphere 6.5 – Datastore Expansion: VMFS version UI Bug

A “what the…? ” moment, expanding a datastore and the GUI indicated that after expansion,  the VMFS version will be VMFS 6…..

As we all know, upgrading the VMFS version of a datastore to VMFS 6  without erasing the contents is not possible, so at face value this looks like a disaster waiting to happen and this is a fairly large Datastore that I was not keen on having to do a restore on,  should it lose its contents during the expansion.

Here’s what is looked like from a single host;

I verified that it is indeed a display bug by simply creating a sacrificial datastore and adding an extent. Expanding it showed VMFS 5, even though the display showed it would be VMFS 6.


You can also expand the datastore using esxcli; from https://kb.vmware.com/s/article/2002461

In my case (which is unique to this datastore, DON’T COPY !)

In action,

Of course, this has a few more steps and assumes you are proficient in disk management,  Be careful, each case is different……

The result;

The moral of the story?

Watch what you are doing and be alert to things that could put your precious data at risk.

So, expand your datastores with confidence that the data will not be hosed.

This is using the following build number revision;
(Updated) VMware-ESXi-6.5.0-8294253-Custom-Cisco-

..and yes, I notified my VMware rep who is following up to make sure it’s fixed in a later build, if it hasn’t been already 🙂






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