Saturday, February 3, 2018

Extended LUN size but unable to increase the datastore size from vCenter

You might have seen this issue where in vCenter managed environment, you want to expand the datastore size and Storage team has confirmed that they have increased the respective LUN size and the same is reflecting in datastore properties under Device capacity however when you click on increase under Volume Properties, there is no extent available.

I had seen such issue in past but when adding additional extents, not when increasing datastore size.

vCenter Server calls a specific function to get all the available extents for that datastore. After getting extents, vCenter Server displays the extents as available if they meet these criteria filters:
  • LUNS are not used as datastores on that host or on any other host (with exceptions to force mounted volumes).
  • LUNS are not used as Raw Device Maps(RDMs) on that host or any other host.
vCenter Server applies these filters to stop any possible data corruption on already used LUNs by other host.
VMware recommends you to not to turn off the filters. Before making any changes to the LUN filters, contact the VMware Support team. 

When you connect directly to the ESX host, these filters do not exist and hence you can see the extents.
To work around this issue, you need to connect to the ESXi directly using 'root' credentials and then increase the volume size from there, once done then re-scan all ESxi hosts for storage. 
Once you do that the expended datastore would be visible to all other ESXi hosts as well. 

Related VMware KB article :- 1011754

That's it... :)


  1. Can you please write the command?

    1. didn't get you, could you please tell me what command you are looking for

  2. I have been having this issue for a while. Your article solved my problem. Thank you so much.