Restore OS X from back up.

Now I am back in calmer waters I have been thinking about how to restore OS X from back up.
The G4 iMac was bought in Apr 2002 with OS 10.1.5 supplied installed [at least that is what I seem to remember] and with OS on CDs.
The internal hard drive was replaced in Apr 2004 and the repairer installed OS 10.2.7 but no CDs were suppled.
In Dec 2004 Apple Software Update provided OS 10.2.8 which has been used till now.
Still no CDs for re-installing OS.

When I make back up copies of the internal hard drive, using Disk Utility to write to LaCie external hard drive, there are various warnings that certain items cannot be copied.
No info is given about exactly what has not been copied.
Difficult to see if OS 10.2.8 has been copied or not, since I do not know which Filenames to look for.
So I have a suspicion that if my G4's internal hard drive gave up, or some other calamity happened, I might not have an OS copy on my LaCie external drive available for use in recovery.

If this is so, how do I make a copy of my OS 10.2.8 for use in a recovery?
Do I need something like CarbonCopy?
Or is the OS protected against copying?

Any ideas?

I do not think I can buy from Apple any replacement OS for a G4 iMac - though I would like to be proved wrong.

I do have access to the CDs containing OS 10.3.9 which came with our G4 iBook, but I don't know if these could be used on a G4 iMac.
In any case, for various reasons involving access to old files, it would be preferable to stick with OS 10.2.8 if possible.

You can use CarbonCopy to make an exact replica of your disk. It will copy everything. If your Lacie disk is firewire then you can even make a bootable copie and boot off your external drive. In your situation, making a clone in this way would seem to be a very good idea.

You can actually still find retail copies of Tiger and Leopard, but not direct from Apple. I wouldn't recommend Leopard if you have less than 1GB of RAM.

Your MacBook CDs would almost certainly not work on the iMac.

You will need CCC 2.3 here http://www.bombich.com/software/files/cccloner-2.3.dmg to make a bootable clone of your current system

Thanks for those replies, which look like just the job.
I will have to study the CCC material carefully before jumping in.

Then assuming that I succeed in creating a 'bootable copy' of OS, then I will have to decide if I want to try it out before I really need to [ which may carry some risk if the bootable copy is imperfect ] or to wait until I really have to use it [ which has its own risks ].
Hmmm ...

But the main thing is that thanks to this Forum I now have a way forward.

As I said before, if your Lacie disk is firewire then you can test the bootable copy by trying to boot from it. That would pose no risk to your existing installation.