Linux – Creating a 80GB image with dd on a FAT32 drive

For quick and dirty sort-of imaging of a Windows box, I boot a SystemRescueCD, and execute the following script (located on an external USB backup drive mounted on /mnt/backup):

 #!/bin/bash

 PCNAME=foobar # or passed in on command line if you prefer

 fdisk -l /dev/sda >./${PCNAME}-fdisk-l.txt
 dd if=/dev/sda of=./${PCNAME}-mbr.bin bs=512 count=1
 dd if=/dev/sda1 of=./${PCNAME}-p1-diag.bin bs=23040
 ntfsclone -s -o - /dev/sda2 | gzip -c | split -b 638m - ./${PCNAME}-p2-win.img.gz.

 # end

Oh, the external drive is usually formatted NTFS, mounted with "-t ntfs-3g".

Having done (almost) exactly this for several years on my laptop (I never replaced my Windows install with a fresh one, though), here are some comments I have:

1. This should work just fine.
2. Linux has no problem living on a single partition, I did it all the time with my small experimental install which in my case was Ubuntu as I run a Redhat Enterprise clone (Scientific Linux) as my primary OS. For your main install you may want to break it up into a few different partitions (e.g. /boot, /, /home, /usr/local) according to your preferences.
3. The partitions I used were 25GB for Windows, 10GB for my "experimental" Linux, and the remaining disk for my main Linux (I have a 120GM hard drive as well). Depending on the size of your existing Windows installation and what you want for your experimental partition you can adjust these as needed. You might want a little more in the experimental Linux partition if you want to install a bunch of stuff to play with.
4. The main issues you'll run into is every time you want to install a new OS on one of the partitions, it will want to update the MBR so that the computer boots from the newly installed OS. I worked around this by first installing Windows, then installing my primary Linux OS. Next I saved the MBR to disk and thumbdrive (i.e. dd if=/dev/sda of=orig.mbr -bs 512 -count 1) Then, whenever you install the secondary Linux you just rewrite the MBR back to the disk and update the menu.txt in the /boot/grub directory to include the reference to your new partition.
5. I'm not sure about what the exact procedure is for installing a previous image of the windows partition. If you can just write to the disk without going through the install process, there shouldn't be any issue. If you have to reinstall and Windows overwrites the MBR you'll need a boot disk to get back into Linux (and LiveCD would work) and rewrite the MBR that you saved to restore you dual boot capability.
6. You can share swap partitions between the two Linux installs.

The laptop in question for me was Intel Core Duo 2GHz with 2GB RAM and 120GB HD. Here is the exact partition table I used but the details aren't that important, it's just to give you an idea:

• Dell utility partition (90MB)
• Windows Partition (25GB)
• /boot (100MB)
• Logical partition (rest of the disk) containing
  • / (10 GB)
  • /usr/local (8 GB)
  • swap partition (4 GB)
  • /home (~55 GB)
  • experimental partition (10 GB)

It may not have been the best (most optimal) partitioning scheme and opinions vary widely on what partitions to create, but it worked just fine for me.