I do this for a server in my LAN. I use DHCP+TFTP to boot grub over the network via PXE, and then grub boots the Kernel with the root pointing to a NFS share:

menuentry 'GNU/Linux NFS' --class gnu-linux --class gnu --class os {
        load_video
        set gfxpayload=keep
        insmod gzio
        insmod part_msdos
        insmod part_gpt
        insmod fat
        echo    'Loading kernel ...'
        linux   <TFTP Root>/vmlinuz root=/dev/nfs ip=dhcp nfsroot=<NFS Server IP>:/export/rootfs/<Root Dir> rw loglevel=6 threadirqs
}

Doing this makes managing that installation much easier. It’s just a directory that lives on the Main Server.
I don’t even need to boot the other Server to update the software in it, chroot is enough. And I don’t even have to worry about doing separate backups, because I already back up the Main Server’s Storage regularly.