But sometimes you meet the 'external hard drive not showing us' issue. (Do keep in mind that there are a lot of counterfeits sold by third parties on Ebay and Amazon so it's equally important to buy your USB flash drive new from a reputable source.What you know: When you plug in an external drive disk utility into your Mac, you expect it to pop up and be showing up on mac in Locations in Finder - next to your remote disk and the computer itself. If all else fails, try a different name-brand flash drive of at least 8 gigabytes or greater in size. Some users have problems creating a successful bootable USB flash drive because they attempt to follow Apple's instructions on older versions of Mac OS X that require Disk Utility, not the Terminal window 'createinstallmedia' command, to create a bootable USB flash drive. If you still can't boot from the USB flash drive, verify that you created the Mac OS installer on the USB flash drive while working in the same (or as close to) current Mac OS as you intend to write to the USB flash drive. If you can't see it, reset the PRAM and try again. On the machine you wish to install on, you can hold down the Option (ALT) key to select the boot drive, select your installer.

Eject the drive if you're ready to remove the USB Drive and install.

Deselect the check box ignore ownership.

Click the padlock icon to unlock administrator options.In the info window, expand the Sharing & Permissions: section.Mounting the USB flash drive on the desktop, right click and select 'Get Info'.The 'missing step', after ensuring the USB flash drive is formatted correctly, is to ignore ownership For this reason, you will need to enable it before/after completing the process described by Apple, MacWorld and others using the 'createinstallmedia' command in the Terminal window. Complicating matters, the USB flash drive default may disable boot support. Most of the guides, including Apple's own support doc on how to create a bootable Mac OS installer on USB - as of this date - fail to mention the ownership step.įirst and foremost, the USB flash drive must support ownership functionality. It may be that boot-up from the USB flash drive is 'prohibited' because your USB flash drive requires adjustment to the 'ownership' settings.

Mac not detecting usb hd at boot