OS X: Cannot install on a volume used by Time Machine for backups
You may be unable to install Mac OS X v10.6 or later on a volume (disk) that Time Machine uses, or used in the past, for backups.
Follow these steps so that you can install on the disk.
Important: You should have a current Time Machine backup on a different disk.
Note: If you do not need the backups that are located on your installation volume, you can simply erase the volume with Disk Utility instead of following these steps. Erasing the disk will result in all loss of all data on it, so be sure you have backup copies of any data before erasing.
- Start up from the disk you want to install on.
- Move the "Backups.backupdb" folder from the root level of your hard drive to the Trash. Enter your admin password if prompted. Important: Do not empty the Trash unless you have a backup on a different disk and want to delete the Time Machine backups from this disk.
- Move the "Backups.backupdb" folder from the Trash to the desktop.