Dell EMC Unity: Newly created VMFS datastore not visible as a datastore, instead seen as a LUN on Vsphere
Summary: Dell EMC Unity: Newly created VMFS datastore not visible as a datastore, instead seen as a LUN on Vsphere
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Symptoms
No host access was given while creating a Datastore
When creating a new VMFS Datastore without Host access and assigning it to vCenter/ESXi host by "modifying the Host access" later. it will then be seen as a LUN and not as a VMFS Datastore.
However assigning a Host access while creating the Datastore in the wizard will create a new Datastore and assign it to the ESXi as a VMFS Datastore This is Working as designed.
When creating a new VMFS Datastore without Host access and assigning it to vCenter/ESXi host by "modifying the Host access" later. it will then be seen as a LUN and not as a VMFS Datastore.
However assigning a Host access while creating the Datastore in the wizard will create a new Datastore and assign it to the ESXi as a VMFS Datastore This is Working as designed.
Cause
Datastore was created without host access.
VMware is integrated with Unity with an API which means when Datastore is created and host access is provided immediately through the Wizard there are certain SOAP API calls that Unity makes to the vCenter such as give me a list of hosts , or rescan the HBA on host 1 when using the vCenter account which was provided to Unity.
Below steps will be executed in the backend when the wizard for Datastore creation with host access is used - This is Working as designed.
- Unity creates a normal LUN
- Unity then connects to vCenter and tells vCenter to rescan the HBAs on all hosts assigned to see the new LUN
- Unity then issues API calls to create VMFS file system on this newly created LUN.
- vCenter would pick a host from the list of host assigned and performs the VMFS partition on that LUN.
- Now all the hosts can see it as a VMFS datastore.
So if we have started a Datastore creation Wizard without presenting to host then we are just creating a normal LUN.
There are several reasons why Unity isn t doing the VMFS Datasore creation
- First is that VMFS is a VMware proprietary format and you don t have a host that vCenter would pick to do the formatting of a LUN to a VMFS6 filesystem/datastore.
-Also each VMFS file system must have a Unique UUID assigned to it. Unity cannot guarantee uniqueness as it does not have a full view into each and every UUID as vSphere does.
VMware is integrated with Unity with an API which means when Datastore is created and host access is provided immediately through the Wizard there are certain SOAP API calls that Unity makes to the vCenter such as give me a list of hosts , or rescan the HBA on host 1 when using the vCenter account which was provided to Unity.
Below steps will be executed in the backend when the wizard for Datastore creation with host access is used - This is Working as designed.
- Unity creates a normal LUN
- Unity then connects to vCenter and tells vCenter to rescan the HBAs on all hosts assigned to see the new LUN
- Unity then issues API calls to create VMFS file system on this newly created LUN.
- vCenter would pick a host from the list of host assigned and performs the VMFS partition on that LUN.
- Now all the hosts can see it as a VMFS datastore.
So if we have started a Datastore creation Wizard without presenting to host then we are just creating a normal LUN.
There are several reasons why Unity isn t doing the VMFS Datasore creation
- First is that VMFS is a VMware proprietary format and you don t have a host that vCenter would pick to do the formatting of a LUN to a VMFS6 filesystem/datastore.
-Also each VMFS file system must have a Unique UUID assigned to it. Unity cannot guarantee uniqueness as it does not have a full view into each and every UUID as vSphere does.
Resolution
Customer needs to provide host access while creating Datastore through the same Wizard.
Note: Make sure VMware is integrated with Unity and have required permission for the added vCenter account.
Note: Make sure VMware is integrated with Unity and have required permission for the added vCenter account.
Affected Products
Dell EMC Unity FamilyProducts
Dell EMC Unity FamilyArticle Properties
Article Number: 000071359
Article Type: Solution
Last Modified: 20 Oct 2025
Version: 4
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