Drive cloning with Disk Utility versus Commercial Apps


I use a product for drive testing named Scannerz with FSE. Today I went to their site to download a troubleshooting doc, and I noticed they added a new how-to section to their site. I took a look and they have an article on there about cloning a hard drive using Disk Utility under Mountain Lion. Here's a link to the article if anyone's interested: Cloning with Moutain Lion.html

I assume that this process can be done with Lion as well, and I'm half guessing that it can be done with Snow Leopard, but using the install DVD instead of the recovery partition.

Back in the "good 'ol days" you used to be able to use a command line utility named "asr" to back up, restore, and clone volumes. I don't have any of the scripts handy I'd do this with, but in one mode you could do a block by block copy, which was faster, but required that the target volume be at least as large as the source volume. Another mode allowed you to clone one volume to another, even if the target was smaller, provided there was enough free space on the volume. This method was slower, but you could do a clone with drives/volumes of differing sizes. I remember thinking to myself that this would make bootlegging the OS really easy. Guess what? Newer versions of asr don't allow that anymore. I think Tiger was the last OS that supported that but I'm not sure.

In any case, the description in the link above, like the block copy mode of asr requires the target volume to be as large or larger than the source volume. This got me to wondering about some of the commercial apps for drive cloning. The two that come to mind are Carbon Copy Cloner, which used to be free, but now it's $39.95, and SuperDuper for $27.95. Do these things support cloning from larger to smaller volumes, assuming there's adequate free space on the target volumes? Any opinions on these? Are they worth the money? I mean seriously, if I can clone a drive for free why should I buy these?



Is your data NOT worth $40? :D
Lots of folks really like CCC, and it gives you lots of options - most of which are not simple from the command line (or not optional with Disk Utility either)
And - CCC gives you the choice of either block-copy, or file-copy.

There's always the unix DD command. Here's an article with some tips on how to use dd.
Yes, the article is about recovering files from a dead hard drive, but if your source volume is working, then the task is simple (and pretty fast, too!)
And, dd is part of your system - also free!
Last edited:


In Geostationary Orbit
Well the big about CCC is the Schedule I can set auto start (set it to work a weekly backup but one could set it any way they want) to clone weekly. If my mac is sleeping during a backup time it asks if I want to go upon the next wakeup.

Now Super Duper is liked because for new user it is very simple. IMHO CCC is better because it can backup over the network also.


One more, for the road!
Now Super Duper is liked because for new user it is very simple. IMHO CCC is better because it can backup over the network also
Superduper backs up over the network, I do regular backups to my synology NAS using SD.
Also, this is for for the original poster...
SuperDuper is totally free, if all you want to do is clone your operating system, period.
The fee payment gets you all the extras such as scheduling and selecting what to back up etc.

Doctor X

I have used SuperDuper! for a number of years. I cannot say which is better since I had it and not CCC. I will say this--it creates a true clone. Back in the day . . . when we had to walk up hill . . . both ways . . . to get to our computers . . . in driving rain, snow, and 120 degrees in the shade . . . Time Machine would not make a true clone. The advantages to a clone is obvious--I can test things on it--like updates. Should I do something "stupid" I can boot from my clone and use SuperDuper! to recreate my original Int HD. I do not have to look for passwords and receipts from programs I have purchased over the years.

Back in those days, on a few online reviews, SuperDuper! had the higher ratings for "exactitude" of cloning.

Most people HERE used the then free CCC and have also spoken well of it.

Frankly, DeltaMac puts it, is your data worth $40?

Back in the day . . . if you frell up your volume or your HD is dying and you did not bother to back everything up, you had to hope you could boot your computer to a *giggle* CD or now DVD with DiskUtilities or the Last Affordable Resort DiskWarrior. And DW has saved my posterior.

Now, in the age of iPods and rock 'n roll, I can check my last clone--make sure it is okay--and simply overwrite a corrupted--as in I frelled it up--volume. If the HD fails, I can still use the computer. Chicks dig me.

Both programs also do an "update" I believe. What that is is after the long cloning of say 500 GB the next time you clone you can just update the clone to where you are. This takes only a few minutes. SuperDuper!--when it does this--does not eat up my processors/RAM--it happens in the back ground whilst I am still watching my French Licen Porn videos. . . .

So . . . either way . . . either one is a "must have." UNLESS someone HERE tells you that Time Machine does the same thing--make a bootable and exact clone. I believe it does now--but since I have SuperDuper! I do not bother.



Interestingly, DeltaMac, I came across that very link to the dd trick prior to writing this post. Interestingly also, is the fact that there's a guy on there with a name that's, well, should I say identical to yours? Is that you?

Just curious. Most people don't even have a clue what dd is.


I've been around these various forums for more than 12 years, and haven't ever seen my user name used by anyone else. In fact, after doing some searching, I've not seen my REAL name anywhere else on the internet, either.

And, not sure where you saw DeltaMac in that article that I linked. I never posted to that one, and DeltaMac doesn't show up there at all.


Actually, I've found this post quite informative. I used to use "dd" a loooooong time ago because back in the days of simple Unix, that's about all that was available for cloning, or possibly cpio (does anyone remember that??) if used properly. Upon realizing that "asr" has been effectively limited, and I assume it's because of bootlegging, I realized that my options were limited. I could use an old Tiger system to clone a drive in a manner that's less restrictive than that described in the link I listed, or I could look at other tools.

Whereas the disk cloning in the link I provided is valuable, provided the drive/space parameters are met and it's free, other posters have pointed out the benefits of the other programs. This is exactly the information I was looking for...input from other users.

....but which one's best?!?!? (LOL)


I notice that you seem to believe that asr is no longer useful, or is deprecated - which is not accurate.
I think many of the third-party cloning utilities ultimately use asr
The OS X Disk Utility/Restore, and Scan functions both use asr, and asr continues to be useful in Mountain Lion.
try a man asr from the terminal for some more info.


From the man page:

When run in its first form above, the --erase option must always be used,
as asr no longer supports file copying. Such functionality is done better by ditto(1).
In Tiger, and possibly Panther as well, asr used to support file copy. For example, suppose you have your drive named "MacHD" and it's 100GB with 60 GB free space, thus the OS and all files are using 40GB, and you want to clone it to MacHD-Clone, which we'll say is an 80GB drive. With the file copy option in earlier Mac OS X versions this was possible. If you formatted the clone drive and then used asr with the file copy options, it would copy the OS and all files from "MacHD" to "MacHD-Clone", even though the size of MacHD-Clone is smaller. All that mattered was that the target had enough free space available to hold the OS and everything else on the source drive. You would end up with a bootable cloned drive that functioned exactly as the source, it was just on a smaller drive. As I stated earlier, I would suspect Apple discontinued this because it's obvious how easy it would be to take a single system and use it to clone its contents onto a host of other systems - all without the actual OS disks (bootlegging). I would think this could still be done in some way, but not by using a single line script file or terminal entry.

I became aware of asr years ago from CCC itself which was free at the time. The author was citing and reporting on trying to clone drives using a host of different tactics including asr, ditto, rsync, dd, and a few others I don't remember.

The block copy used in asr now is the only thing allowed to the best of my knowledge, and this means the target must either be the exact same size as the source or larger. I would suspect something like CCC and other, similar products may use a combination of tactics to clone drives and not be limited to just asr. I would suspect asr or it's equivalent functionality is built into Disk Utility or called by exec'ing asr in another thread or process.
Last edited: