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I need to switch the hard drive on a 2006 iMac to a new SSD. I don't have the original installation CDs. I know I can order CDs from Apple, but this costs money.

Someone told me it's possible to rip the image of the old drive and transfer to the new drive. If so, does the size of the new drive have to be exactly the same as the old?

If not, my questions are:

  1. Is it possible to "stretch" the image from 120 MB disk to a 256 MB disk (numbers are examples)? If so, what is the command line for this?

  2. Likewise, is it possible to "shrink" an image from a larger disk (eg. 256 MB) to a smaller disk (eg. 120 MB), provided that the actual space used on the disk does not exceed 120 MB? How do you do this on the command line?

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Yes, it's totally possible to clone a drive onto a larger disk. You can get a pretty cheap external enclosure and a cloning application called SuperDuper. You just specify the source and destination drives. A 120GB (I think you meant GB not MB) disk would take around 3 hours to copy. I use this enclosure to do this all of the time:

Yes, it's possible to clone onto a smaller drive as long as the space used is slightly less than the destination.

If you just want to install your OS onto a new drive, there is a way to get the install onto a USB drive. You need to download Lion Disk Maker (it works with Mountain Lion too): The only problem is that you need to extract the InstallESD.dmg from the installation disk image, and OS X deletes it after the install. The way to get another one is to reinstall the OS directly from Apple or redownload it from the App Store (if that's where you got it from).

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Is Lion Disk Maker able to magically create an installation image from my already-installed files? Like I said, I have no original CD's, and Snow Leopard is not available as a download anymore. Or, another option, is there possibly a utility that can create an installation image for my machine by combining 1) the installation CD's belonging to another machine, with 2) some unique identification number on my hard drive. (I wouldn't classify this as illegal since all you're doing is re-create installation CD's that you once owned but lost) – forthrin Nov 28 '12 at 17:24
No. You need to extract InstallESD.dmg from the download. After installation, the install package is deleted. I had the same problem since I upgraded a week before. I re-downloaded from the App Store and extracted it from there. Once you have the download, navigate to your Applications folder in the Finder and right click on the file “Install Mac OS X Mountain” and select “Show Package Contents.” Look in the “Shared Support” folder located under the “Contents” folder of the “Install Mac OS X Mountain,” and copy the file named “InstallESD.dmg” to your desktop. – Ian Atkin Nov 28 '12 at 18:57
Note that Ian's answer also applies to every OS I can think of. Imaging a disk and restoring it the larger drive is a extremely common use case. Only the other day, I used DriveImage XML to image the 4 GB SD card from my cell phone and restored it to a 32 GB replacement. – Isaac Rabinovitch Nov 28 '12 at 21:59

We are using CarbonCopyCloner to clone one harddisk onto another one. Simply attach the new disk to your mac and clone the comtent of your current harddisk onto the new one.

The new one has to have at least the size of the currently used space. I would recomend at least about 15% additional space.

You can get carbonCopyCloner via the App-Store. There once was also a free version but I am not sure where to get that.

And AFAIK CarbonCopyCloner uses rsync under the hood, so that would be your commandline tool

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