Most Linux distributions now support the ability to install directly to an iSCSI (or FCoE, or other SAN protocol) target disk. You can use the Linux distribution's own installer in conjunction with a bootloader such as iPXE to install the operating system onto the iSCSI disk. When you do this, the installer will automatically configure the installed operating system to be able to boot from an iSCSI target disk.
If you originally installed the operating system to a local disk (rather than to an iSCSI target disk), then the installer will not set up the configuration required to support booting via iSCSI. You can take an image of the local disk containing the installed operating system and copy it to an iSCSI target disk, but the operating system will not be able to boot successfully because it will be missing some required configuration.
The sanbootable package solves this problem by providing the
configuration required to allow a Linux operating system to boot from
either a local disk or an iSCSI target.
Download and install the latest version of
sanbootable.rpm:
sudo yum install https://github.com/ipxe/sanbootable/releases/latest/download/sanbootable.rpm
Download and install the latest version of
sanbootable.deb:
curl -OL https://github.com/ipxe/sanbootable/releases/latest/download/sanbootable.deb
sudo apt install -y ./sanbootable.deb
After installing the sanbootable package, you can freely transfer
your disk image from a local disk to an iSCSI target disk or vice
versa.
The sanbootable code will detect at boot time whether the operating
system is being booted from a local disk or from an iSCSI target, and
will automatically adjust the system configuration as needed.