When using a Cisco UCS C-Series rack servers in it’s standalone form (not connected to Fabric Interconnects, so not managed through the UCS Manager), you can boot it using a few options: local storage, fiberchannel connected storage, PXE boot and iSCSI.
When you don’t have fiberchannel at your disposal for central boot, iSCSI will do just fine.
The configuration inside the C-Series CIMC is a bit hidden though, here’s how you do it. Login to your CIMC and follow this procedure:
1. Go to Inventory
2. Select the ‘Cisco VIC Adapters’ tab
3. Select the ‘vNICs’ sub-tab
4. Click ‘Add’ to create a new vNIC
5. Give your vNIC a name, I went with ‘iscsi’
6. Be sure to enable “Enable PXE Boot”
Once you have create the vNIC that will handle the iSCSI network traffic, you can configure the iSCSI boot process. First, select the vNIC you just created and click ‘iSCSI Boot’. Here you can configure the vNIC settings, such as the IP address (or DHCP), boot target (primary and secondary) and LUN ID.
When everything iSCSI is configured (check screenshots below for examples), the last thing you should check if whether PXE boot is enabled in the Boot Order.
Credits go to Martijn Smit for this description!