Boot Linux Mint Debian Edition squashfs from HDD

This is a simple way to boot the compressed squashfs contained within the LMDE.iso directly from a hard drive.
This equates to the same thing as booting from a DVD just without the DVD.

Why would you want to do this?
Makes for a handy backup.
Nearly an unbreakable OS - you just need GRUB to boot it.
Perhaps you're out of blank media.
It's faster than burning a blank.

First we need to extract some files from the .iso image. Get root

# mkdir loopmount  
# mount -o loop /path/to/linuxmint-debian-201009-gnome-dvd-i386.iso loopmount  
# ls loopmount  
total 5  
dr-xr-xr-x 2 root root 2048 Apr 29 03:32 isolinux  
dr-xr-xr-x 2 root root 2048 Sep 5 10:10 casper  
-r--r--r-- 1 root root 526 Sep 5 10:12 md5sum.txt  

Now that the .iso is loop mounted we can copy files onto the hard drive:

# mkdir /casper
# cp loopmount/casper/* /casper

You can make sure it's all there:

# ls /casper
total 894932
-r--r--r-- 1 root root     30208 Sep 24 09:51 filesystem.manifest-desktop
-r--r--r-- 1 root root     30240 Sep 24 09:51 filesystem.manifest
-r-xr-xr-x 1 root root 906858496 Sep 24 09:52 filesystem.squashfs
-r--r--r-- 1 root root   7190389 Sep 24 09:52 initrd.lz
-r-xr-xr-x 1 root root   2287264 Sep 24 09:52 vmlinuz

Now to make it bootable.

For grub-pc
Create a file something like this:

# cd /etc/grub.d/  
# cat >> 41_LMDE_squash << EOF  
menuentry "Linux Mint Debian squashfs" {  
set root=(hd0,1)  
linux /casper/vmlinuz boot=live live-media-path=/casper quiet splash vga=791  
initrd /casper/initrd.lz  
}  
EOF

# chmod +x 41_LMDE_squash;update-grub2

For grub-legacy
Add an entry to /boot/grub/menu.lst

title  LMDE
root   (hd0,0)
kernel   /casper/vmlinuz boot=live live-media-path=/casper quiet splash vga=791
initrd  /casper/initrd.lz

*Note*
You can still access the partition that the image was booted from mounted @ /live/image
If you intend to use the squashfs as a repair tool you might want a seperate partition for the squashfs itself.
This way you can still chroot into any other partition.