Based on the information you provided, I can suggest a few areas to investigate and some possible solutions:
1. Double-check the UCS iSCSI Boot Configuration:
Ensure that the UCS iSCSI boot configuration is correctly set up. This includes verifying the iSCSI vNICs, boot targets, and LUN settings in the service profile. Also, ensure that you have the correct boot order, with iSCSI boot as the primary option.
2. Verify the iSCSI VLAN Configuration:
Make sure that the iSCSI VLAN is properly configured on both the UCS Fabric Interconnects and the upstream switches. Ensure that the VLAN is allowed on all relevant interfaces and that proper tagging is in place.
3. Confirm the iSCSI Initiator and Target Settings:
Check the iSCSI initiator settings on the UCS blades and ensure they match the target settings on the Nimble SAN. This includes confirming the iSCSI Qualified Name (IQN) and authentication settings if required.
4. Update Firmware and Drivers:
Ensure you are using the latest firmware and drivers for the UCS blades, Fabric Interconnects, and Nimble SAN. Compatibility issues between different firmware and driver versions can cause unexpected behavior.
5. Check the Boot LUN Configuration on the Nimble SAN:
Verify that the Boot LUN is correctly configured on the Nimble SAN, and ensure that it is mapped to the correct iSCSI initiator IQN. Make sure the LUN is set to be bootable.
6. Review ESXi Installation Logs:
After the installation of ESXi, review the installation logs (e.g., /var/log/esx_install.log) for any errors or issues related to iSCSI boot or connectivity.
7. Verify BIOS Settings on UCS Blades:
Ensure that the UCS blade BIOS settings are configured to support iSCSI boot. This may include enabling the iSCSI boot option in the BIOS and configuring the correct boot order.
If you've already checked these areas and are still experiencing issues, I recommend opening a support case with Cisco TAC for further assistance. They can help you with in-depth troubleshooting and provide insights specific to your environment.
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