Replacing root disk with a smaller one.

In this example we will be replacing a single disk system with two partitions one for root and one for swap. After physically installing the disk boot OS and notice the name (CTRL+S top - CTRL+Q uit) or find it from dmesg after login. On a higher level it can also be found with fdisk -l Start with partitioning the disk. One primary, leave enough for double your physical RAM if you have less than 16GB or else make it equal the size. One extended, for swap. Now mkfs.ext4 /dev/hdX1 And mkswap /dev/hdX2 Mount the /dev/hdX1 to lets say /mnt Start copying files cp -rav /srv/ /mnt/ cp -rav /media/ /mnt/ cp -rav /lib64/ /mnt/ cp -rav /lib/ /mnt/ cp -rav /home/ /mnt/ cp -rav /opt/ /mnt/ cp -rav /usr/ /mnt/ cp -rav /bin/ /mnt/ cp -rav /sbin/ /mnt/ cp -rav /boot/ /mnt/ cp -rav /root/ /mnt/ cp -rav /etc/ /mnt/ cp -av /cdrom/ /mnt/ Go to /mnt and link the kernel files ln -s boot/vmlinuz-4.15.0-70-generic vmlinuz.old ln -s boot/vmlinuz-4.15.0-72-generic vmlinuz ln -s boot/initrd.img-4.15.0-70-generic initrd.img.old ln -s boot/initrd.img-4.15.0-72-generic initrd.img Do a blkid and note the UUID for you new disk and replace the one in /mnt/etc/fstab Replace the swap drive now your add it anyway. Now its time to leave the comfort of your multi user system and drop into single user mode with telinit 1 rSync the rest with -avhPHAXx chroot to your new disk system and mount -B the rest of the file systems. Only thing left is to update-grup and install-grup. Reboot and change boot order in disk. Not working? change the boot order back and try again, no harm done :)