Problem getting iMac to install Yosemite from bootable USB drive

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Level 1

6 points

Problem getting iMac to install Yosemite from bootable USB drive

I've just replaced the dead HD on my old iMac and can't get my Bootable USB drive to work.

I restart the mac and hold down the option key and the USB shows then when I click on the drive it just freezes.

I have an external drive with OSX installed and can run the iMac off of that and the new drive is detecting properly and I've reformatted the drive to the needed format.

I can also run the installer on the usb from within OSX and select the new hard drive as the install destination but when it restarts it just opens the OSX from the external drive instead of continuing the install on the new internal HD.

Could the fact I'm booting from a USB thumbnail drive be the problem? Would a powered external be better?

Thanks in advance for any helper pointers.

Posted on Dec 17, 2018 12:27 PM

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Answer 1

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Slumberjack Author

Level 1

6 points

Dec 21, 2018 2:42 AM in response to Slumberjack

Thanks for the replies...

After trying different USB memory sticks I finally managed to get it to install by using an old powered external storage device I had knocking around.

I think either the USB was drawing too much power to initiate the install or the package at over 5GB was too large for the USB sticks to run.

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Answer 2

Dec 17, 2018 1:18 PM in response to Slumberjack

Not entirely certain of the sequence or the issue here...

I'll assume you've created your installer using the Apple createinstallmedia tool.

If the USB flash device is giving you trouble, try a different flash drive.

There are any number of sketchy and counterfeit and mislabeled drives around, and drives that are having hardware problems.

And also make sure you have an empty external USB bus when you're testing this, as hard drives and other external devices—those without external power or a powered USB hub—can draw too much power from the USB and cause problems with the bus. Connect only the USB flash drive, and—if you're using one or both of these with your iMac—a wired keyboard and a wired mouse.

You may also need to use the Startup Manager to select your new boot device.

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Answer 3

Eric Root

Level 10

684,045 points

Dec 17, 2018 1:39 PM in response to Slumberjack

Can you boot off the external drive, download the installer from the App Store, and run the installer from the external? During the install sequence, there is a screen where you can choose the drive you want to install on. Select the internal there and complete the installation.

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Problem getting iMac to install Yosemite from bootable USB drive

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