Newly created LUNs not showing up on ESXi hosts

Products

• VMware vSphere ESX 8.x

Issue/Introduction

Symptoms:

• Mapped LUNs are not visible from the vCenter Server or ESXi host storage view.

• Storage rescans via the vSphere Client or CLI (`esxcli storage core adapter rescan --all`) do not discover the expected devices.

Environment

VMware ESXi 7.x

VMware ESXi 8.x

Cause

This issue typically occurs due to one of the following environment-specific factors:

• Non-Uniform LUN ID Presentation: The LUN ID assigned to a device on the storage array is not consistent across all hosts in the ESXi cluster. vCenter Server filters out devices that do not have a uniform presentation to ensure data consistency.

• Incorrect Storage Masking/Zoning: The LUNs have not been correctly masked to the specific World Wide Names (WWNs) or iSCSI Qualified Names (IQNs) of the ESXi host adapters.

Resolution

1. Perform a storage rescan on the ESXi hosts.

2. Verify basic storage connectivity:

1. Confirm FC/iSCSI link status is UP.
2. Validate physical and SAN/network connectivity.

3. Check whether the device is visible under:

   ESXi Host → Configure → Storage Devices

   Filter/search using the assigned LUN identifier:  `naa.####` or `eui.####`

4. Alternatively, verify the device details from the ESXi SSH session using:

   esxcli storage vmfs extent list | grep -i <LUN number>

5. Verify with the storage vendor/team that:

1. Backend LUN mapping is configured correctly.   
2. LUN presentation is consistent across all ESXi hosts.
3. Storage masking/zoning configuration is properly applied.

6. Once the storage-side validation is completed and confirmed, perform a fresh rescan of the storage adapters on the ESXi hosts to rediscover the devices.

7. If the devices are still not visible after the rescan and connectivity checks, further investigation is required at the storage infrastructure layer.