Because I find DU convoluted. Also it doesn't provide a solution for scheduled updates.
I concur with some of the other comments made here. I use CCC and find it an excellent investment that has saved my bacon numerous times.
One caveat about your question: your external drive should be the same size as your internal drive + at least about 15-20% more.
Drive Preparation of the New Drive
1. Open Disk Utility in your Utilities folder.
2. After DU loads select your hard drive (this is the entry with the mfgr.'s ID and size) from the left side list. Click on the Partition tab in the DU main window.
3. Under the Volume Scheme heading set the number of partitions from the drop down menu to one. Click on the Options button, set the partition scheme to GUID then click on the OK button. Set the format type to Mac OS Extended (Journaled.) Click on the Partition button and wait until the process has completed.
Clone using Restore Option of Disk Utility
1. Open Disk Utility in the Utilities folder.
2. Select the destination volume from the left side list.
3. Click on the Restore tab in the DU main window.
4. Select the destination volume from the left side list and drag it to the Destination
5. Select the source volume from the left side list and drag it to the Source entry field.
6. Double-check you got it right, then click on the Restore button.
Destination means the new drive. Source means the old drive.
I use Carbon Copy Cloner all the time to copy data from one external to another. Note that CCC supports block copy which might be necessary if you're copying Time Machine data (CCC will alert you if needed). I use CCC to keep a clone of my 2TB 'working' drive to a 2TB backup of my working drive and have never experienced any problems. CCC is no longer free, but you can use the trial version to see if it will work for you.
Why not use Disk Utility? Other forums say dont use CCC or Super Duper.
Because SuperDuper and Carbon Copy Cloner have proved themselves year after year to be rock solid drive cloning utilities.
SuperDuper is free for a full disk clone. You pay if you want incremental updating of the clone and scheduling.
I use both utilities and highly recommend both. And as mentioned by macjack, SD & CCC are easier to use.
I got a new G Drive, also 1TB, 7200 RPM, it has failed 2 times using CCC. (it also failed the same way with disk utility). After nearly 2 hours of sending the data to the new disk, it stops a message which says "The mountpoint for the destination drive has changed" something like that. There are also other messages (pop ups) which say more or less the same thing, meaning for whatever reason, the new drive was disconnected, or at least the computer thought that was the case. The new G Drive is a mini and does not have a power supply, it gets its power by being connected to the laptop or chained (via firewire 800) to the other drive. One more try, but if anyone has heard of this, please help if you know. thanks much. Rich
...After nearly 2 hours of sending the data to the new disk, it stops a message which says "The mountpoint for the destination drive has changed" something like that....
This is starting to sound like a hardware problem.
First try connecting each drive to a separate port. If possible 1 via USB and 1 via Firewire. This will do 2 things.
1st, they devices will not need to share any of the power provided by their ports.
2nd, it should eliminate any interference on the same port (many USB ports share a common USB controller, and chaining Firewire has both devices sharing components).
If the new G-Drive has an option for separate power, or if as some mobile devices do, you can connect Firewire for the data, and ALSO a USB cable for extra power, that might be a way to make sure the bus powered new G-Drive has sufficient power.
If you have another Mac, try moving the external disks to the other Mac and see if the problem happens there.
If all else failes, see about replacing the new G-Drive, as it will then have proved to not meets your needs.
There have been no issues with the repair report each time. I erase the partially written data from the new disk. As this has happened 3 times, it seems to happen with about the same timing. I only have one firewire port on my mac, so it is necessary to chain them, but others have told me this should be no issue.
I changed the order of the disks, now the new, empty G Drive is plugged directly to the laptop, the source G Drive plugged into the new drive. The new drive did not come with a power supply, I suppose one has to purchase that separately. I will bet the Apple store does not have it. On my fourth try as I am writing here. Its a bummer as these transfers will take all day long, thus eliminating getting any editing done, and I am behind