Virtual machines fail to power on or migrate, and the environment reports that no compatible host is available.

Products

• VMware vSphere ESXi

Issue/Introduction

• The vSphere Client returns the error: No host is compatible with the virtual machine. The user specified host is not compatible.
• The iSCSI software adapter (e.g., vmhba68) shows no active paths or targets.
• A vmkping from the iSCSI VMkernel port (e.g., vmk2) to the storage processor's IP fails.
• The /var/log/vmkernel.log or /var/log/hostd.log contains the following entry: ALERT: Login to iSCSI target iqn.####.com.#### on vmhba68 @ vmk2 failed. The iSCSI initiator could not establish a network connection to the target.

Environment

VMware vSphere ESXi

Cause

This issue occurs when a physical layer failure or an environmental network blockage disrupts the specific iSCSI communication path. Common causes include:

• A faulty physical switch port connected to the ESXi host's iSCSI uplink.
• A damaged network cable.
• Physical switch configuration errors (e.g., VLAN mismatch or port security blocking traffic).
• Guest Operating System network configuration errors that prevent the virtual machine from accessing required storage resources.

Resolution

Follow the steps below to identify and resolve the connectivity failure:

1. Inspect the Physical Layer: Check the physical switch ports associated with the ESXi host's iSCSI uplinks. Identify any "Link Down" states, CRC errors, or port flaps on the switch side.
2. Remediate Hardware: Replace the network cable or migrate the connection to a known working physical switch port.
3. Verify Switch Configuration: Ensure the physical switch port is configured for the correct VLAN and that MTU settings (e.g., 9000 for Jumbo Frames) are consistent end-to-end.
4. Rectify Guest OS Settings: Verify that the Guest OS has not introduced network conflicts or routing changes that prevent it from communicating with the mapped storage resources.
5. Rescan Storage:
   • Log in to the vSphere Client.
   • Select the affected ESXi host.
   • Navigate to Configure > Storage Adapters.
   • Select the iSCSI software adapter and click Rescan Storage.
6. Verify Path Health: Navigate to Storage Devices > Paths and ensure all paths for the LUNs are listed as Active or Active (I/O).

Additional Information

Datastores and devices are not visible on certain ESXi hosts.