Unble to boot from a couple 64 GB USB flash drive with mac OSes?

[Ant]

Hello.

In a 13.3" 2012 MacBook Pro (MBP) with its old updated Mac OS X/Mountain
Lion v10.8.5, I used https://support.apple.com/en-us/HT201372's
instructions to make a bootable Mac OS (v10.12.4 Sierra and v10.11.6 El
Capitan from App Store) onto a 64 GB PNY flash drive. I saw no errors
after several minutes.

When I reboot/power up this MBP and hold down its C key to boot from it,
I get its light gray screen for about a minute and then it takes to its
internal SSD's old Mac OS X's FileVault login screen. I tried two
different 64 GB USB PNY flash drives. How come it didn't work? I don't
have another Mac at the moment to try on. I can see the contents on the
flash drive though in Finder. Also, its Startup should nothing bootle
from this drive. Maybe the bootable part failed or something?

Thank you in advance. :)
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[David Empson]

Ant <ANT...@zimage.com> wrote:

> Hello.
>
> In a 13.3" 2012 MacBook Pro (MBP) with its old updated Mac OS X/Mountain
> Lion v10.8.5, I used https://support.apple.com/en-us/HT201372's
> instructions to make a bootable Mac OS (v10.12.4 Sierra and v10.11.6 El
> Capitan from App Store) onto a 64 GB PNY flash drive. I saw no errors
> after several minutes.

"After several minutes"? You need to let it run to completion, which
will probably take ten minutes or more. It is finished once the command
prompt returns, after which you can eject the drive.

> When I reboot/power up this MBP and hold down its C key to boot from it,
> I get its light gray screen for about a minute and then it takes to its
> internal SSD's old Mac OS X's FileVault login screen.
>
> I tried two different 64 GB USB PNY flash drives. How come it didn't work?
> I don't have another Mac at the moment to try on. I can see the contents
> on the flash drive though in Finder.

On Macs with an optical drive, the C key boots from that is used to boot
from the optical drive (C for "CD" is the original reason that key was
chosen).

To boot from a USB flash drive on that model on a one-off basis, you
need to hold down the Option key at startup, which brings up a boot disk
selector screen with an icon for each bootable device found. You can
then choose the USB flash drive with the mouse or arrow keys, and click
or press Return to boot from it.

> Also, its Startup should nothing bootle from this drive. Maybe the
> bootable part failed or something?

That description was a bit mangled: did you mean that the flash drive
doesn't show up in System Preferences > Startup Disk?

If so, you probably did something wrong in the process of using the
createinstallmedia tool. It should show up as a bootable device.
--
David Empson
dem...@actrix.gen.nz

[Ant]

In comp.sys.mac.hardware.storage David Empson <dem...@actrix.gen.nz> wrote:
> Ant <ANT...@zimage.com> wrote:

> > Hello.
> >
> > In a 13.3" 2012 MacBook Pro (MBP) with its old updated Mac OS X/Mountain
> > Lion v10.8.5, I used https://support.apple.com/en-us/HT201372's
> > instructions to make a bootable Mac OS (v10.12.4 Sierra and v10.11.6 El
> > Capitan from App Store) onto a 64 GB PNY flash drive. I saw no errors
> > after several minutes.

> "After several minutes"? You need to let it run to completion, which
> will probably take ten minutes or more. It is finished once the command
> prompt returns, after which you can eject the drive.

No, it was done. It took several minutes to complete all that.

> > When I reboot/power up this MBP and hold down its C key to boot from it,
> > I get its light gray screen for about a minute and then it takes to its
> > internal SSD's old Mac OS X's FileVault login screen.
> >
> > I tried two different 64 GB USB PNY flash drives. How come it didn't work?
> > I don't have another Mac at the moment to try on. I can see the contents
> > on the flash drive though in Finder.

> On Macs with an optical drive, the C key boots from that is used to boot
> from the optical drive (C for "CD" is the original reason that key was
> chosen).

> To boot from a USB flash drive on that model on a one-off basis, you
> need to hold down the Option key at startup, which brings up a boot disk
> selector screen with an icon for each bootable device found. You can
> then choose the USB flash drive with the mouse or arrow keys, and click
> or press Return to boot from it.

Ah, Option key worked. https://support.apple.com/en-us/HT201255 is
confusing with its "Start up from a bootable CD, DVD, or USB thumb drive
(such as macOS install media)." :(


> > Also, its Startup showed nothing bootable from this drive. Maybe the

> > bootable part failed or something?

> That description was a bit mangled: did you mean that the flash drive
> doesn't show up in System Preferences > Startup Disk?

Yeah, sorry. I fixed it above. I forgot to proofread that part. ;)

> If so, you probably did something wrong in the process of using the
> createinstallmedia tool. It should show up as a bootable device.

Nah, that part worked since it said "done" at the end. C doesn't boot
it, but Option key did.

[David Empson]

The C key will boot from USB on the MacBook Air, or other models newer
than your one which do not have a built-in optical drive. Apple just
didn't cover all cases in their support article.

--
David Empson
dem...@actrix.gen.nz