Resolving LUN Visibility Issues from a storage array Caused by Conflicting ESXi NMP Claim Rules

Products

• VMware vSphere ESXi

Issue/Introduction

 This article explains how to resolve an issue where storage paths to LUNs from a specific storage array are marked as "Dead" or categorized as an "Unregistered Device" on an ESXi host. This behavior occurs even when the storage array confirms the zoning and masking are configured correctly.

Symptoms

• The issue is isolated to one storage array; LUNs from other arrays remain visible on the same FC HBA cards.
• This command esxcli storage san fc list output confirms that the FC HBAs are online, active, and functioning.
•  vmkernel.log shows that the Native Multipathing Plugin (NMP) is actively rejecting the affected storage paths (e.g., vmhba3:C0:T7:L61 and L62).

2026-08-04T06:09:22.010Z In(182) vmkernel: cpu31:2098031)ScsiClaimrule: 2523: Error claiming path vmhba3:C0:T7:L61. Failure.
2026-08-04T06:09:22.010Z Wa(180) vmkwarning: cpu31:2098031)WARNING: NMP: nmp_PspSet:525: Switching to claimrule PSP "VMW_PSP_RR" for device Unregistered Device.
2026-08-04T06:09:22.010Z Wa(180) vmkwarning: cpu31:2098031)WARNING: NMP: nmp_SatpClaimPath:2188: SATP "VMW_SATP_ALUA" could not add  path "vmhba3:C0:T7:L62" for device "Unregistered Device". Error Not supported
2026-08-04T06:09:22.010Z Wa(180) vmkwarning: cpu31:2098031)WARNING: NMP: nmp_DeviceAlloc:2184: nmp_AddPathToDevice failed Not supported (195887136).
2026-08-04T06:09:22.010Z Wa(180) vmkwarning: cpu31:2098031)WARNING: NMP: nmp_DeviceAlloc:2205: Could not allocate NMP device.
2026-08-04T06:09:22.010Z Wa(180) vmkwarning: cpu31:2098031)WARNING: ScsiPath: 7748: Plugin 'NMP' had an error (Not supported) while claiming path 'vmhba3:C0:T7:L62'. Skipping the path.
2026-08-04T06:09:22.010Z In(182) vmkernel: cpu31:2098031)ScsiClaimrule: 2041: Plugin NMP specified by claimrule 65535 was not able to claim path vmhba3:C0:T7:L62: Busy

• The issue persists even after removing custom user-defined SATP rules via standard CLI commands (e.g., esxcli storage nmp satp rule remove).

 

 

Environment

• VMware vSphere ESXi 8.x
• VMware vSphere ESXi 9.x

Cause

The issue is caused by the presence of multiple, conflicting user-defined NMP (Native Multipathing Plugin) claim rules stored within the ESXi ConfigStore database. These user-defined rules override the system's default SATP (Storage Array Type Plugin) rule, preventing ESXi from correctly claiming the storage LUNs.

Resolution

Follow these steps to remove conflicting rules:

1. Export the existing NMP claim rules to a JSON file for review: configstorecli config current get -c esx -g storage -k nmp_claim_rules -outfile /tmp/nmp_rules.json
2. Review /tmp/nmp_rules.json to identify the cs_generated_id for conflicting "User Perm" rules or other conflicting entries.
3. Delete each conflicting user-defined SATP rules using the configstorecli utility  configstorecli config current delete -c esx -g storage -k nmp_claim_rules -i "<cs_generated_id>" (Repeat this command for each unique cs_generated_id identified in step 2
4. Reload the claim rules to apply the changes: esxcli storage core claimrule load
5. Rescan storage adapters: esxcli storage adapter rescan --all
6. Confirm the LUNs are now visible and correctly claimed by the system default SATP rules.

Additional Information

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