To create a disk image of a partition, the command is: sudo hdiutil create ~/Desktop/ For the purposes of this guide, we'll be using it to create new disk images (although there is a lot more the command can do). The first, hdiutil, is used to manipulate disk images. The diskutil command is only for disk management, when it comes to creating and restoring images there are two other commands to know of. Rather then repeat the entire configuration process on each Mac, it could be completed on just one Mac and a disk image of it created, then restored to every other Mac. This is especially useful for those needing to configure tens, if not hundreds, of similar Macs with the same software configuration.

If we then restored this disk image to another external hard drive, it would contain the exact same volume with identical information.ĭisk images also retain boot functionality, so images created from bootable OS X volumes can be created and restored. Let's say we had an external hard drive that contains a single volume and created a disk image from it. If you remember the days of software that was provided on either a floppy or optical disc, disk images have been designed to work in much the same way but through digital, rather than physical, distribution.Ĭreating an image of a disk partition duplicates its entire structure into a single file, bit for bit. You'll likely have come across these when downloading apps, such as Skype, from the web. On the Mac, disk images tend to be DMG files. Disk Images ExplainedĪ disk image is a file containing the entire structure of a partition or even just a folder. It's an integral part of Disk Utility and, as with partitioning, creating & restoring images can be executed via the command-line.

Disk imaging is a highly useful tool if you're wanting to create a whole copy of a volume and restore it back at a later date, either to the same disk or another one entirely.

Resize a mac disk image