Troubleshooting LUN connectivity issues on ESXi hosts
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Troubleshooting LUN connectivity issues on ESXi hosts


Article ID: 323129


Updated On:


VMware vSphere ESXi


This article provides troubleshooting steps when LUNs are missing:

  • Targets on the storage array are visible but one or more LUNs are not visible
  • LUN not visible
  • LUN cannot connect
  • LUN is missing
  • LUN not presented


VMware vSphere ESXi 6.5
VMware vSphere ESXi 5.1
VMware vSphere ESXi 8.0.x
VMware vSphere ESXi 6.7
VMware vSphere ESXi 5.5
VMware vSphere ESXi 7.0.0
VMware vSphere ESXi 6.0


Validate that each troubleshooting step below is true for your environment. Each step provides instructions or a link to a document, in order to eliminate possible causes and take corrective action as necessary. The steps are ordered in the most appropriate sequence to isolate the issue and identify the proper resolution. Do not skip a step.
  1. Verify that the LUN is presented to the ESXi host. You may need to contact your array vendor for assistance.
    1. Verify that the LUN is in the same storage group as all the ESXi hosts (if applicable to the array).
    2. Verify that the LUN is configured correctly for use with the ESXi host.

      Note: Consult the appropriate SAN configuration guide for your array (listed in the Additional Information section).
    3. Verify that the LUN is not set to read-only on the array.
    4. If you are presenting LUN IDs that are higher than 255, please ensure Disk.MaxLUN setting on the ESXi host is set higher than the range you are using. Please see: . Further...
      1. If you are presenting (in total) more than 255 LUNs from an array, please make sure that your HBA driver supports it, for example Cisco UCS manager has a "Max LUNs Per Target" field that is defaulted to 256, but is recommended to be 1024 for ESXi hosts.
  2. Verify that the ESXi  host can see the LUNs. For more information, see Obtaining LUN pathing information for ESXi hosts (1003973) .

    Note: If LUNs are not visible on the ESXi host, see:
  3. Verify that a rescan restores visibility to the LUN(s). For more information, see Performing a rescan of the storage on an ESXi/ESX host (1003988) and Interpreting SCSI sense codes in VMware ESX / ESXi (multiple versions) (289902).
  4. Check the storage for latency. For more information, see Using esxtop to identify storage performance issues (1008205).
  5. Verify that there are not excessive SCSI reservation conflicts. For more information, see: Resolving SCSI reservation conflicts (1002293)

Note: If your problem still exists after trying the steps in this article:

Additional Information

VMware Skyline Health Diagnostics for vSphere - FAQ
"Host Connectivity Degraded in ESXi" warning in vCenter Server
For translated versions of this article, see: "An error occurred while consolidating disks:" deleting one or more snapshots or consolidate disks
Unable to create a VMFS3 partition on a metaLUN or LUSE LUN
Resolving SCSI reservation conflicts
Troubleshooting fibre channel storage connectivity
Troubleshooting iSCSI LUN connectivity issues on ESX/ESXi hosts
Collecting diagnostic information in a VMware Virtual Infrastructure Environment
Obtaining LUN pathing information for ESX or ESXi hosts
Performing a rescan of the storage on an ESX/ESXi host
Insight Manager may cause SCSI reservation conflicts
Using esxtop to identify storage performance issues for ESX / ESXi (multiple versions)
ESXi 5.0 host does not boot with a new VMFS5 LUN as LUN0 on fibre channel storage array
ESXi hosts fail to mount VMFS5 volumes that are formatted with ATS-only capabilities
How to file a Support Request in Customer Connect
ESXi/ESX ホストの LUN 接続の問題のトラブルシューティング
对 ESXi/ESX 主机上的 LUN 连接问题进行故障排除
Interpreting SCSI sense codes in VMware ESXi and ESX
SCSI Reservation Issue with Fibre Channel HBAs