here's how to make it without software via command line, but if you only have drag the visible folder of OSX on the external HD you can't clone it. Secondly, I would not clone this set-up since both hardware haven't the same processor architecture (one is G5, the other G4). It shouldn't be a problem but maybe some appz may have install only some 64 bit code in them.
N.B.: this wasn't written by me, I don't remember where I took it, please feel free to provide a link.
How to Create a Bootable Backup of Mac OS X (Cloning Mac OS X disks)
Update: Clone Mac OS X disks without Mac OS 9
If you're looking for the article about using Apple Software Restore from OS 9 to create bootable backups, look here. The rest of this article has been updated to cover cloning/backing up OS X exclusively in Mac OS X.
Introduction
I have examined Mac OS X extensively, and discovered 1) that cloning is possible from OS X with the utilities that Apple has provided and 2) that there are a few basic rules that you need to follow when cloning a disk with Mac OS X System files in order to get a bootable clone:
1. File permissions must be preserved.
Many files belong to the root user, so you cannot simply copy these files from the Finder. There are other issues with permissions, such as the setuid bit (in English, that is a feature of a file that, when executed, gives the file or application
the same privileges as the owner of the file; if the owner of the file is root, then root privileges are granted during the execution of this file). Copying via the Finder sets the owner of the new files to the user that copied them and assigns a default set of permissions. Many applications and system files will not work properly with the default Finder settings.
2. The invisible Unix system files must be copied.
Mac OS X is driven by a Unix flavored operating system called Darwin. Darwin system files reside at the root level of the derive in four folders: /private, /bin, /usr, and /sbin. These directories hold all the critical files that allow the computer to boot up and have basic functionality.
3. Unix-style links must be preserved.
Symbolic links and hard links are different from the Mac aliases we are familiar with. Likewise, the way we deal with them will not be the same. Because there are some critical symbolic links on a Mac OS X disk, the integrity of these files must be preserved by the utility you use to clone/backup the disk. Some people are very familiar with the error upon booting that states "/etc/master.passwd: Not a directory". This is because the /etc symbolic link to /private/etc was broken.
4. Some directories are populated by the System after booting, and are thus unnecessary to preserve, however, although empty, they may still have to be present.
Some directories are populated by the System. For example, the Volumes directory is populated with directories corresponding to the names of Volumes you have on your system. If you insert a Zip disk, a new directory in /Volumes is created with the name of the Zip disk. These directories are called "mountpoints", and are created "on-the-fly" by Apple's autodiskmount utility. Because these directories do not contain data on your boot volume, they do not need to be copied during a clone operation. The Volumes directory is just a placeholder (and the OS will recreate the Volumes directory on bootup, so it is unnecessary to recreate). The /dev directory is also a placeholder for system devices, such as disk drives, output devices, and communications devices. The list of devices in this directory is created each time the computer is booted up and when new hardware is added, so it is unnecessary (and a little difficult) to copy the items in this directory. Because this is a Unix system directory, however, you will not have a bootable volume unless this directory is recreated on the cloned disk. Creating an empty directory is sufficient. Likewise, it is important to backup mach_kernel (the most important file in the system), but "mach" and "mach.sym" are destroyed and recreated each boot by the /etc/rc boot script. Finally, the Network folder at the root level does not need to be backed up because it is populated by the System on startup.
5. Resource forks must be preserved
While Apple is trying to move away from Resource Forks, there are still many applications and documents that use them. Because of this, any backup or cloning utility must preserve the resource forks. If you try to clone a Mac OS X disk without preserving resource forks, many of your personal documents will be damaged and the drive will not be bootable.
Pre-flight checklist
1. Make sure the "Ignore privileges on this volume" setting is not checked for your source or target volume. To check this setting, click on the target volume, choose "Show Info" from the File menu in the Finder and select the Privileges menu. Make sure the box at the bottom is NOT checked, otherwise permissions and ownership settings will not be preserved, no matter what tool you use to copy files.
2. Unlock source files if you plan to use ditto. This is a hotly debated topic. Ditto fails when it gets to locked files (even though it actually copies the file successfully), so unlocking all files prevents errors during cloning.
In general, this is not a problem unless you specifically want a file to be locked -- files that are locked on OS X were probably locked under OS 9. There aren't any locked files in a standard installation of Mac OS X. File locking, as far as I can tell, is just a method of preventing a file from being deleted or modified. I suppose some applications have files locked for a reason, but I've never come across any, and the fact that files are locked usually is just an annoyance. Please note that some people disagree with this statement, and with good intention. Once the files are unlocked, if you did not know which ones were locked, that information is lost. You may re-lock files when the clone is finished, but if you have several hundred files that you want to stay locked, you may want to look for an alternative method. Also, Netboot servers lock the Netboot images, so you will want to pay close attention to these files when using this method. Most people will have no problems at all with unlocking their files, but this is something you should decide for yourself.
To unlock files on your drive, type:
sudo chflags -R noschg,nouchg /
in the Terminal to unlock all files on your hard drive.
3. Run Disk Utility on the target and source volumes before cloning. This is not required, but is a good idea to avoid disk or directory-related problems during cloning. If you are cloning to an external Firewire device, I recommend that you format (not simply erase) the drive with Disk Utility prior to cloning.
Cloning a disk or backing up your drive with ditto:
Ditto is a command-line utility that ships with Mac OS X. Ditto preserves permissions when run as root and preserves resource forks when run with the "-rsrc" flag. Ditto is pretty easy to use to clone a Mac OS X disk. It is my preferred utility for cloning because it involves very few steps. Ditto can be used to clone your system with the following steps:
1. Use ditto to copy each of the visible directories from your boot volume to your backup volume. You need to repeat this step for each visible file/folder at the root level of your drive*:
* sudo ditto -rsrc /Applications /Volumes/Backup/Applications
* sudo ditto -rsrc /Developer /Volumes/Backup/Developer
* sudo ditto -rsrc /Library /Volumes/Backup/Library
* sudo ditto -rsrc /System /Volumes/Backup/System
* sudo ditto -rsrc /Users /Volumes/Backup/Users
6. Use ditto to copy your Darwin system files*:
* sudo ditto -rsrc /private /Volumes/Backup/private
* sudo ditto -rsrc /usr /Volumes/Backup/usr
* sudo ditto -rsrc /bin /Volumes/Backup/bin
* sudo ditto -rsrc /sbin /Volumes/Backup/sbin
* sudo ditto -rsrc /mach_kernel /Volumes/Backup/mach_kernel
* sudo ditto -rsrc /.hidden /Volumes/Backup/.hidden
7. Recreate symbolic links and empty directories:
* cd /Volumes/Backup
* ln -s private/etc etc
* ln -s private/var var
* ln -s private/cores cores
* ln -s private/tmp tmp
* mkdir dev Volumes Network
7. Bless the System (OS X) (and System Folder [OS 9] -- if copied) on the target:
* sudo bless -folder /Volumes/Backup/System/Library/CoreServices
* sudo bless -folder9 /Volumes/Backup/System\ Folder
The last step is not always required, but recommended for good measure. You must at least select it as the boot disk in the Startup Disk Preference Pane if you would like to boot from it.
That's it! That's the big secret. You should now have a bootable clone of your OS X partition.
* The following files/folders at the root level are unnecessary to backup: "dev", "Volumes", "Network", "etc", "cores", "tmp", "var", "automount", ".vol", "mach", "mach.sym", ".DS_Store", "Cleanup At Startup", "TheVolumeSettingsFolder", "File Transfer Folder", "Trash", ".Trashes", "TheFindByContentFolder".
