Reinstall mac operating system lion

Even with the differences, you can still create a clean installation of Lion on an internal drive, a partition, an external drive, or a USB flash drive. This step-by-step article looks at installing Lion on a drive or partition, either internally on your Mac or on an external drive.

How to Install (or Reinstall) Mac OS X Mountain Lion

For those of you who want to create a bootable USB flash drive with Lion installed, check out the guide: Purchase Lion from the Apple Store online. You receive a content code to the Mac App Store, usually within one day. After you download the installer, copy it to any Mac that meets the minimum hardware requirements and install Lion. The Lion installer is downloaded to your Applications folder, and it is just under 4 GB in size.

The system requirements are:. You can install Lion on any internal drive, including SSDs solid state drives. The Lion Recovery partition takes MB of the free space.

How to Install (or Reinstall) Mac OS X Mountain Lion - dummies

The Lion installer creates two partitions, one for Lion and one for recovery tools. You can use the Recovery Partition to repair drives, fix permissions, and format drives, as well as reinstall Lion if needed. The Recovery Partition includes a bootable system with Disk Utility.

Mac OSX Lion How to do a Clean Install

The target volume should be erased at best; at a minimum, it should not contain any OS X system. With previous versions of OS X installers, you could erase the target drive as part of the installation process. With the Lion installer, there are two methods of performing a clean install. One method requires you to create a bootable Lion install DVD, and the second lets you perform a clean install using the Lion installer you downloaded from the Mac App Store.

How to reinstall Mac OS X from scratch

The difference between the two methods is that to use the Lion installer directly, you must have a drive or partition that you can erase before running the installer. Using a bootable Lion install DVD allows you to erase a drive or partition as part of the installation process. If you're going to perform a clean install of Lion on a drive other than your current startup drive, then you're ready to proceed. Before you begin the Lion installation process, back up your existing OS X system and user data. Performing a clean install on a separate drive or partition shouldn't cause any data loss with your current system, but stranger things have happened, and it is best to be prepared.

At a minimum, make sure you have a current backup. For more protection, make a bootable clone of your current startup drive. You can find the method here: Back Up Your Mac: You must erase the target drive before you can start the Lion installation process. Remember that to use the Lion installer as downloaded from the Mac App Store, you must have a working copy of OS X to start the installer from.

A drop-down sheet will appear, asking you to confirm that you wish to erase the target disk. Click Erase.

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  • How to Perform a Clean Install of OS X Lion on Your Mac!

Disk Utility will erase the drive. A list of disks will appear; select the disk you wish to install OS X Lion on. This should be the same disk you erased earlier. Click the Install button. The Lion installer will copy the necessary files to the target disk. The installer may also download necessary components from the Apple web site. In our installation tests, there were never any downloads, but this feature may ensure that the installation has the latest updates, and there may not have been any current updates.

A progress bar will display, with an estimate of the time to copy the needed files. Once all the necessary files are copied to the target disk, your Mac will restart. After your Mac restarts, the installation process will continue.

Step 2: Erase the hard drive

A progress bar will display, with an estimate of the installation time, which can run from 10 to 30 minutes. Once you see the installation progress bar, the install process is identical to steps outlined in the following article:. Finish the installation by following from page 4 of the article: Share Pin Email. Tom Nelson has written hundreds of articles, tutorials, and reviews for Other World Computing and About. He is the president of Coyote Moon, Inc. It will simply remove the current system and replace it with a fresh copy. None of your data will be deleted or moved.

The only thing that will be replaced will be the core system files. There is no longer any need to make backups, migrate your data, or mess with partitioning. If you'd like to read more about the Lion Recovery function, go here: Download Lion. The install eats the file you need so don't install it right away. Now, if you installed it you can do the brutal cmd-R on boot to get to the recovery partition. That's nice, you can now install Lion via your hopefully working network, as well as wiping the badness from your drive.

Break out one of your many 16 gig USB keys and erase it.

Reinstalling Lion

Check with diskutil, the gui in Lion is sexy, but underneath is a sea of malloc 3 -y kernel panics. It needs to be bootable. It' won't boot. You should be back in what looks like the same place, except it should be from your USB key, which can install lion onto the wiped hard drive. I shall attempt this last part right now, all I want is the oblivion of the zeroes Very useful debugging stuff. Why is it "secret? Super cool tool. I'll use it instead of watching the 14 gigs It is a cool tool though.

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This actually did work quite well for me, the usb key even booted my lappy, and I only forgot to save Xcode, which is going on the key right now.