iMac HD dead – can I run it from external HD?

iainjhamilton

iainjhamilton

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I can start up the Mid-2011 iMac from an external drive loaded with High Sierra OS, but is there a way I can actually use this as a regular drive? All I see when it boots up is Disk Utility etc. Looking for a short-tern fix now until the repair shops reopen and I can get a new internal HD.
 
Once you start up with the external drive, do to System Preferences>Startup Disk and select that external drive as your start up.
 
Cheryl said:
Once you start up with the external drive, do to System Preferences>Startup Disk and select that external drive as your start up.
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Thanks, I did that, but still only got the basic Disk Utility dialogue box when it restrted from the external HD. I am hoping i can use the external drive instead of an internal drive with access to apps. Looking at using Carbon Copy Cloner
 
I have a suspicion that your external drive was not set up as bootable. When you use CCC, make sure you select bootable copy.
 
Cheryl said:
I have a suspicion that your external drive was not set up as bootable. When you use CCC, make sure you select bootable copy.
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Thanks for your help. Is that something I have to select? I don't see any option to make the copy bootable. Or is it automatic?
 
If you boot to a menu, showing Disk Utility, and Reinstall macOS, and a couple of other choices, and not to an actual desktop, with a dock, etc, then you are just booting to a recovery system, or even a bootable installer. You can use that to reinstall macOS as a full system, but it is not a full system, per se. Another item that you will have is a Utilities menu, with probably 3 items: Terminal, Startup Security utility, and Network Utility.

How large is that external drive? is it a USB flash drive (thumb drive), or an actual external storage with (at a minimum to be usable) 120GB of capacity?
If you are booting to an installer (which might be only 8GB size volume), then you just need to have a drive with enough space for a full system install. That's where you can use that drive, if it is 120GB or more.

You can use that Disk Utility to see what drives are there, and how large those drives might be.
 
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As for CCC, the latest version (I looked it up) does an automatic bootable copy if the external drive is large enough.
 
DeltaMac said:
If you boot to a menu, showing Disk Utility, and Reinstall macOS, and a couple of other choices, and not to an actual desktop, with a dock, etc, then you are just booting to a recovery system, or even a bootable installer. You can use that to reinstall macOS as a full system, but it is not a full system, per se. Another item that you will have is a Utilities menu, with probably 3 items: Terminal, Startup Security utility, and Network Utility.

How large is that external drive? is it a USB flash drive (thumb drive), or an actual external storage with (at a minimum to be usable) 120GB of capacity?
If you are booting to an installer (which might be only 8GB size volume), then you just need to have a drive with enough space for a full system install. That's where you can use that drive, if it is 120GB or more.

You can use that Disk Utility to see what drives are there, and how large those drives might be.
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Thanks this makes sense – I have a 8GB installer USB thumb drive (with OS High Sierra as I understand that's the limit of the 2011 iMac), and a 1TB WD My Passport drive which I attempted to install on. Unfortunately, I received the following message:

"You may not install to this volume because the computer is missing a firmware partition".

I used Disk Utility to erase the drive and used the usual parameters Mac OS Extended (Journaled) and GUID partition map.
 
You are trying to install High Sierra, which will change the format of the partition to APFS during the macOS install.
I wonder if it would help to use Disk Utility to change the volume format to APFS before the system install?

(Were you already running High Sierra on the internal drive? or an older system, and you had not installed High Sierra previously on this iMac?)
 
DeltaMac said:
You are trying to install High Sierra, which will change the format of the partition to APFS during the macOS install.
I wonder if it would help to use Disk Utility to change the volume format to APFS before the system install?

(Were you already running High Sierra on the internal drive? or an older system, and you had not installed High Sierra previously on this iMac?)
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The internal drive was running Lion OS I think. The drive is no longer accessible, so I'm hoping to run everything off the external drive until I can get a new drive installed.

I originally made a clone using CCC of my Macbook Pro (which showed up as a startup disk option in disk utility) but it was not visible as a startup disk on the iMac.
 
I think that the installer might not be allowing the firmware to update, when the install destination is not an internal drive. I see that happens on some Macs.
You may have better luck by installing El Capitan, for example. That does not need to force an update to recognize an APFS volume, so might be less trouble to get the install to complete.
 
DeltaMac said:
I think that the installer might not be allowing the firmware to update, when the install destination is not an internal drive. I see that happens on some Macs.
You may have better luck by installing El Capitan, for example. That does not need to force an update to recognize an APFS volume, so might be less trouble to get the install to complete.
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Thanks for this – I tried El Capitan, and got to within a "few seconds" of completing the install before the restart and then – it just hung. Tried several times. So close! Any other ideas? I appreciate your help.
 
Your W-D My Passport is a hard drive, not an SSD, correct?
Each newer macOS system gets less "love" on spinning hard drives. Much more optimization on SSDs.
Consequently, installing on a spinning hard drive can install in "jumps and jerks", with the progress indicator that isn't very dependable.
How long did you wait? I would probably give up after 2 hours, when there is no obvious progress happening. You could even let it go overnight, maybe it will eventually finish.
 
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