How to create a mountable ISO image file

You could have a look to the application called mondorescue

This is a recovery tools that will allow you to create bootable CD or DVD images that can be reused to reinstall your system even if you insert a new hard disk into it. The software consists intot two main executable mondoarchive and mondorestore.

Options are foreseen in the tools to

• split the image into multiple files if the total size exceed the size of a CD or DVD,
• exclude some directories
• specify different destination media like network share, USB, ...

Of course, read carefully the documentation and test because some special disk layout may not be able to be archived using this tools.

During the restore of such an image, you can be prompted to enter dialog where you can alter the disk partitions layout, in case you do the restoration on a system where the disk is smaller (of course it cannot be smaller that the total used size of the orginal system !)