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2011 iMac running Sierra

I would like to have a copy of macOS that I can actually boot from and use on a USB key, so that I can run Carbon Copy Cloner from it to make backups of any volume on the machine at any time. I previously had a dedicated small partition on one of my drives for this purpose, but that drive died and going forward I would rather have this on a USB stick.

To be clear, I don't want a "bootable installer". I want a fully functional bootable macOS on the stick, i.e. it boots into Finder, etc. All the answers I've found related to this, are about creating bootable installers.

Can this be done and if so, how?

JVC
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    This seems a bit of an XY Problem. There's no need to boot from another OS drive to run CCC, it works perfectly well on any volume, including the one you're booted from. – Tetsujin Nov 15 '20 at 17:35
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    What version of macOS are you running and on what model of Mac? – user3439894 Nov 15 '20 at 17:36
  • But I want to make a clone of the very volume I would be booted from, and I didn't think that was supported? – JVC Nov 15 '20 at 17:36
  • Updated the OP to include mac model and OS – JVC Nov 15 '20 at 17:36
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    I've been using CCC to clone my boot drive for probably a decade, without issue. – Tetsujin Nov 15 '20 at 17:37
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    Then Carbon Copy Cloner or SuperDuper! should be able to clone to an external USB drive and it be bootable. (At the present moment they do not work on macOS Big Sur to make bootable clones.) – user3439894 Nov 15 '20 at 17:38
  • Wow interesting, thanks. I never even attempted to clone the active boot drive simply expecting it to fail! I'll give it a shot. – JVC Nov 15 '20 at 17:42
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    It will even add a Recovery Partition too, if you want one. – Tetsujin Nov 15 '20 at 17:45
  • @Tetsujin I am trying to clone my boot drive now, but CCC states "You will not be able to boot from the destination volume". Does it mean that I will have to create a bootable drive from the image (well duh of course I would), or something else? It goes on to say they "strongly recommend that you create a bootable backup of your startup disk to a locally-attached URB or Thunderbolt drive." This is making me unsure if this will actually result in an image I can use to recreate my boot drive it I need to. – JVC Nov 15 '20 at 18:10
  • Create a bootable macOS installer, boot from it, and then select another USB stick as your target disk. (So, you need two USB sticks total.) – Wowfunhappy Nov 15 '20 at 18:15
  • JVC - It's a message I have never seen. I'd check Bombich's FAQ for what might cause that. – Tetsujin Nov 15 '20 at 18:17
  • Just out of curiosity..why not run recovery (or the Installer) and select the USB flash/disk as your target. That's the easiest way to install a full macOS onto a USB drive. I've done this with 32GB thru 128GB USB flash drive (like a SanDisk Cruzer). You can then install your cloning tool like a normal app. Boot to it by hold Opt and selecting it in the boot manager screen. – Allan Nov 15 '20 at 18:38
  • @Allan Hmmm that was basically the entire thrust of my post, as it's exactly what I want to do. I didn't think the recovery installer would allow installing on such a small volume, my memory tells me that it required something like 64GB minimum or somesuch, but I've been wrong before. Once. =) I will give this a try and see. – JVC Nov 15 '20 at 18:46
  • FYI @Allan, since moments after my response to you, I have been installing Sierra onto my 32GB USB key. It finally rebooted to complete the install this morning, and has now been stuck at what looks like about 85% complete for most of the day. I feel like it's probably dead but I can't tell. Regardless, this approach is not looking good I'm afraid. =( – JVC Nov 17 '20 at 00:09
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    That happens sometimes to internal disks as well (walked someone through it on here yesterday - see comments) and is not indicative of this method not working. Simply wipe the drive and try again – Allan Nov 17 '20 at 03:55

1 Answers1

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Carbon Copy Cloner or SuperDuper! can to clone to an external USB drive and it be bootable. (At the present moment they do not work on macOS Big Sur to make bootable clones.)

For versions of macOS prior to macOS Mojave, other options include:

  • Booting with a macOS USB Installer and then use Disk Utility to image the drive to another USB flash drive.

  • Creating a macOS USB Installer on one USB flash drive and actually installing macOS to another USB flash drive.

    • (This option actually can be used on macOS Mojave and later.)
user3439894
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  • I've read your answer numerous times, and I'm fairly sure that this is not what I was asking. I am not wondering how I can clone an image to another drive, that can later be used to make a bootable drive. I'm asking if I can install macOS, fully functional, to a USB key which I can boot off of, in order to run CCC (or whatever else). – JVC Nov 15 '20 at 19:09
  • @JVC, My answer show multiple ways to get macOS on to a USB drive as a working running full version of macOS. You either have to install macOS to the USB drive, just like doing a clean install to the internal drive, or clone an existing running version of macOS to the USB drive. That is exactly what my answer provides and if that is not what you want, that is to have a fully functions running version of macOS on a USB drive, then please clarify your question. – user3439894 Nov 15 '20 at 19:26
  • OK, that does sound like what I'm looking for, but your answer seems to only be talking about cloning an existing system to another drive, and having that clone be bootable. It does not mention anything about installing a fresh working macOS directly onto a flash drive. – JVC Nov 15 '20 at 19:29
  • @JVC RE: " It does not mention anything about installing a fresh working macOS directly onto a flash drive." -- , It most certainly does!... "Creating a macOS USB Installer on one USB flash drive and actually installing macOS to another USB flash drive.." – user3439894 Nov 15 '20 at 19:31
  • But I am not looking to "create a macOS USB Installer on one USB flash drive" I am looking to install macOS, fully working. Not an installer. I stated in my OP that I am not looking to create a bootable installer. – JVC Nov 15 '20 at 19:32
  • @JVC Then the only other way I can think of would be to boot to Internet Recovery and install macOS to the USB drive, if it will allow you to pick it over the internal drive in that process. Have never done an Internet Recovery to verify it. You do after all have to have the installer somewhere to do it! – user3439894 Nov 15 '20 at 19:36
  • Which is what Allan suggested in his comment (though standard recovery not internet), and I am doing now. So far so good but it is still installing and going to take a while as it is slow USB. – JVC Nov 15 '20 at 19:54