I have a Mac Mini configured just the way I like it with 10.10.2 installed. I need to deploy that to a bunch of other computers around campus. The usual process for me in the past has been to use an external USB drive, with OS X installed, to boot the target Mac and capture an image. That really doesn't seem to be working in Yosemite. I can boot to my 10.10.2 USB drive and run Disk Utility, but odd things happen when I try to create an image. When I try to image the partition, OS X doesn't dismount the target partition/disk. In past versions of OS X, the target partition was immediately dismounted after I entered my password. Lastly, I cannot "scan the image to restore", that part fails even though I can successfully create the image file. The error message is: Unable to scan "image.dmg" (internal error). Has anyone else seen this? I've tried making several images already.


  • not really an answer, but I'd try Carbon Copy Cloner [£27.50 or equivalent] It has a 30-day unlimited trial so you can test if it works for you before committing. – Tetsujin Mar 27 '15 at 18:24
  • @Jason Does the source Mac contain a CoreStorage partition? Please check this with diskutil cs list. – klanomath Mar 29 '15 at 19:09

If you are able to mount the drive, you can use Copy Copy Cloner or even better (IMO) SuperDuper! from Shirt Pocket. SuperDuper! will not copy caches and unnecessary files that are re-created upon boot, saving space. These both give you clones of the drive, but not images. If you can restore the clone, then this might work.

If you're savvy with a Terminal, you can use the basic diskutil and dd commands to get a disk image - this is what Disk Utility is likely doing under the hood. Just be careful with the input/output parameters of the command, to ensure you don't overwrite something you're not supposed to.

For example, you can find a disk and the partition you want with:

diskutil list

Then, to unmount the disk:

diskutil unmountDisk /dev/disk<n>

where the "<n>" is the disk number of the drive you want to image. Finally, create an image using some form of:

sudo dd if=/dev/disk<n>s<p> of=/path/to/image.img bs=1m

where the "<n>" is the disk number and "<p>" is the partition number you found above. Do not type any of the brackets (<>) as part of the command. There are other options you can add, and you can adjust the block size (bs) accordingly.

I just found more information at another post here: What is the best way to clone a disk between two Macs?

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  • I'll check out SuperDuper and CarboCopyCloner. I was able to image from a USB HDD that is running OS X 10.9.5 "Mavericks" without a problem. I wonder if this is a bug with Yosemite. – Jason Mar 29 '15 at 18:41

The short, simple answer is DeployStudio. It's free and it's built for the exact purpose of creating and deploying OS X images. It can run in a standalone configuration or it can be configured on a server to capture and deploy images over a network. It has a host of post-flight operations available including performing Active and Open Directory binding. We've used it on our campus for the last three years and it's a massive time-saver, network images can be rolled out in minutes, depending on your network speed. There's a bit of a learning curve but this is the tool you need - check it out.

If you need to avoid using network deployment due to speed restrictions etc., DeployStudio can be set up to work from a bootable external disk. A brief setup guide can be found here.

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  • I've had a tremendous amount of difficulty in trying to get DeployStudio to work. The software, which is free and I shouldn't complain about it too much, is flaky and very difficult to use. Our network is slow. When I was able to get DeployStudio to work, the deployment time was around three hours for a 25GB image, across different subnets. And that is if it works, which has a 50/50 probability. I can do the same with a hard drive in twenty minutes, which is why I need to get the hard drive approach working. Thanks – Jason Mar 29 '15 at 18:38
  • Wow, sounds like your setup has some serious issues. Our network is only 100MBit and the server sits on a different subnet to the mobile and desktop subnets, but deployment time only takes around 15 minutes. Can't remember the image size but it's around the 30GB mark, including a Win 7 image for later deployment via Winclone. Did you see my remark about it having a standalone mode? This uses an external drive, which is what you want, instructions here - tech.its.iastate.edu/macosx/downloads/DeployStudioInstrux.pdf – ScunnerDarkly Mar 29 '15 at 18:58
  • Thanks for the instructions. I'll certainly take a look at them, as I do want to get DeployStudio working at some point. It works fine on the same subnet. Then, it takes around 10 minutes to do the same image. It is just imaging across subnets that is the real time sink. – Jason Mar 30 '15 at 19:36

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