Unable to expand datastore by adding a new extent from vCenter.

Products

• VMware vSphere ESXi

Issue/Introduction

Symptoms : 

• While expanding a VMFS datastore by adding a new extent via vCenter, the Increase Datastore Capacity wizard do not list any available LUNs.
  
• While expanding other datastore in the same vCenter, new extents shows up under "Increase datastore capacity".
  

Environment

• VMware vSphere ESXi 7.x
• VMware vSphere ESXi 8.x

Cause

One of the requirement for performing a datastore expansion via vCenter Server is that the underlying LUNs must be presented consistently across all ESXi hosts. This issue occurs because the LUN ID for the head extent is not uniform across all hosts.

Cause Validation:

• Enable trivia logging on vCenter VPXD. Refer to Increasing VMware vCenter Server and VMware ESXi logging levels
• With trivia logging enabled, the /var/log/vmware/vpxd/vpxd.log file on vCenter confirms that vCenter filtered out candidates due to visibility or transport type mismatches
  2026-04-10T11:13:11.176+05:30 verbose vpxd[07207] [Originator@6876 sub=Vmomi opID=########] [ClientAdapterBase::InvokeOnSoap] Invoke done (##.##.###.##, vim.host.DatastoreSystem.queryAvailableDisksForVmfs)
2026-04-10T11:13:11.490+05:30 verbose vpxd[07207] [Originator@6876 sub=MoHostConfig opID=########] Removed all candidates because all LUNs in the datastore are not visible by the same hosts or have the same transport types
• Running the command "esxcfg-mpath -b" on all hosts confirms that the LUN ID differs between hosts:
  Host             Example of a path 
##.##.###.AA     vmhba64:C1:T2:L13
##.##.###.BB     vmhba64:C1:T2:L13
##.##.###.CC     vmhba64:C1:T2:L15
##.##.###.DD     vmhba64:C1:T1:L15
• The LUN ID difference can also be verified from vCenter UI:
  • Navigate to each Host > Configure > Storage Devices. Select the head extent and verify the LUN ID.

Resolution

Engage storage vendor to ensure the LUN presentation is unique and consistent across all hosts.

Work Around: Expand the datastore via the host client using "Add an extent to existing VMFS datastore" option. Refer, Extending or increasing a datastore through vCenter Server fails