booting installed linux through iscsi

[MultimediaMan]

If you are wanting to move a running installation of Linux on a local hard disk to an iSCSI LUN, you are going to have to do some fairly extensive work to accomplish the task;

I assume your iSCSI LUN is identified on the running installation as /dev/sdb (although it could be anything).

General Compatibility Checklist:

a. EFI Secure Boot to iSCSI is not currently possible.
b. Most newer Linux Distributions require that SELinux be disabled for iSCSI/NFS boot.
c. iSCSI boot with iPXE doesn't use GRUB or GRUB2, typically.
d. Your Linux Distribution of choice will need the development kernel, dracut and dracut-network installed before attempting to perform the migration.
e. Your kernel will need to be configured to support iSCSI/NFS boot and your initrd/initramfs will need to be rebuilt with the modified settings (particularly cached /etc/fstab, iSCSI and network settings).
f. You will need to edit your /etc/fstab to reflect the new disk mount points. This operation may need to be done before "e." above.
g. You will need to DD /dev/sda to /dev/sdb at some point.
h. iPXE will essentially become your bootloader, and you will need some sort of a boot script to accomplish the boot. I highly recommend writing the script with robust checks and error handling.

Closing thoughts:

It is easier to install to iSCSI than move a running Distribition to iSCSI (needed to say that).

Thin and Thick Clients should not share a single iSCSI mount unless it is Read Only. For this reason (and many others), I recommend using NFS Roots boot for Thin/Thick Clients in most cases. iSCSI is pretty messy protocol, and while it does work well, there are easier ways to get the functionality without some other overhead.

Best,
M^3