The iSCSI protocol can be used to install Ubuntu on systems with or without hard disks attached, and iBFT can be used to automate iSCSI setup on installation and boot.
Installation on a diskless system
The first steps of a diskless iSCSI installation are identical to the Installation using debian-installer section up to “Hard drive layout”.
The installer will display a warning with the following message:
No disk drive was detected. If you know the name of the driver needed by your disk drive, you can select it from the list.
Select the item in the list titled login to iSCSI targets.
You will be prompted to enter an IP address to scan for iSCSI targets with a description of the format for the address. Enter the IP address for the location of your iSCSI target and navigate to <continue> then hit ENTER
If authentication is required in order to access the iSCSI device, provide the username in the next field. Otherwise, leave it blank.
If your system is able to connect to the iSCSI provider, you should see a list of available iSCSI targets where the operating system can be installed. The list should be similar to the following :
Select the iSCSI targets you wish to use.
iSCSI targets on 192.168.1.29:3260:
[ ] iqn.2016-03.TrustyS-iscsitarget:storage.sys0
<Go Back> <Continue>
Select the iSCSI target that you want to use with the space bar. Use the arrow keys to navigate to the target that you want to select.
Navigate to <Continue> and hit ENTER.
If the connection to the iSCSI target is successful, you will be prompted with the [!!] Partition disks installation menu. The rest of the procedure is identical to any normal installation on attached disks. Once the installation is completed, you will be asked to reboot.
Installation on a system with disk attached
Again, the iSCSI installation on a normal server with one or many disks attached is identical to the Installation using debian-installer section until we reach the disk partitioning menu. Instead of using any of the Guided selection, we need to perform the following steps :
Navigate to the Manual menu entry
Select the Configure iSCSI Volumes menu entry
Choose the Log into iSCSI targets
You will be prompted to Enter an IP address to scan for iSCSI targets. with a description of the format for the address. Enter the IP address and navigate to <continue> then hit ENTER
If authentication is required in order to access the iSCSI device, provide the username in the next field or leave it blank.
If your system is able to connect to the iSCSI provider, you should see a list of available iSCSI targets where the operating system can be installed. The list should be similar to the following :
Select the iSCSI targets you wish to use.
iSCSI targets on 192.168.1.29:3260:
[ ] iqn.2016-03.TrustyS-iscsitarget:storage.sys0
<Go Back> <Continue>
Select the iSCSI target that you want to use with the space bar. Use the arrow keys to navigate to the target that you want to select
Navigate to <Continue> and hit ENTER.
If successful, you will come back to the menu asking you to Log into iSCSI targets. Navigate to Finish and hit ENTER
The newly connected iSCSI disk will appear in the overview section as a device prefixed with SCSI. This is the disk that you should select as your installation disk. Once identified, you can choose any of the partitioning methods.
Warning
Depending on your system configuration, there may be other SCSI disks attached to the system. Be very careful to identify the proper device before proceeding with the installation. Otherwise, irreversible data loss may result from performing an installation on the wrong disk.
Installation with iBFT
In order to setup iSCSI based on the iBFT (iSCSI Boot Firmware Table) on the installation and boot, append these options at the installer prompt (or to the preseed file):
disk-detect/ibft/enable=true partman-iscsi/iscsi_auto=true
This should probe for iBFT information and configure network interface(s) and iSCSI target(s) accordingly during the installation, and configure system boot (initramfs) to do that too in order to find the root device.
Warning
The support for iBFT is available in the debian-installer on netboot images as of 2019-06-20 and (expected) on ISO images for the 18.04.3 point release and later.
Rebooting to an iSCSI target
The procedure is specific to your hardware platform. As an example, here is how to reboot to your iSCSI target using iPXE
iPXE> dhcp
Configuring (net0 52:54:00:a4:f2:a9)....... ok
iPXE> sanboot iscsi:192.168.1.29::::iqn.2016-03.TrustyS-iscsitarget:storage.sys0
If the procedure is successful, you should see the Grub menu appear on the screen.