Creating a bootable installer for macOS

[Alwyn]

Given the age of my wife's iMac 2011 I decided to use a spare SSD to use in the event of her HDD crashing. The instructions on the Apple website seem unnecessarily complicated (Create a bootable installer – Apple Support (UK)). I note these are from the UK website so maybe it just hasn't been updated.

Provided the full High Sierra 10.13.6 has been downloaded the install asks where you want it installed. I had initially formatted the SSD as AFPS but that wasn't recognised so presumably it is only later versions that can use it.

I reformatted it to macOS extended and it installed successfully. I then used Carbon Copy Cloner to clone from the HDD to the external SSD and rebooted to the latter. That worked fine but for some reason Startup Disk wouldn't allow me to restart from the internal HDD so I had to shut down manually, unplug the SSD and restart.

The SSD is a SanDisk Extreme and, as I understand they are not as reliable as other SSDs, I will store it away until needed. How easy is it to boot up after an internal HDD has crashed?

 

[ferrarr]

Did you create a Bootable USB Installer to a USB flash (thumb) drive?

 

[MacInWin]

Given the age of my wife's iMac 2011 I decided to use a spare SSD to use in the event of her HDD crashing. The instructions on the Apple website seem unnecessarily complicated (Create a bootable installer – Apple Support (UK)). I note these are from the UK website so maybe it just hasn't been updated.

Provided the full High Sierra 10.13.6 has been downloaded the install asks where you want it installed. I had initially formatted the SSD as AFPS but that wasn't recognised so presumably it is only later versions that can use it.

I reformatted it to macOS extended and it installed successfully. I then used Carbon Copy Cloner to clone from the HDD to the external SSD and rebooted to the latter. That worked fine but for some reason Startup Disk wouldn't allow me to restart from the internal HDD so I had to shut down manually, unplug the SSD and restart.

The SSD is a SanDisk Extreme and, as I understand they are not as reliable as other SSDs, I will store it away until needed. How easy is it to boot up after an internal HDD has crashed?

It's farly easy to boot from an external. However, a 2011 iMac is getting pretty long in the tooth, so even if the internal drive hangs on, something else may well break after 13 year's service. Here is Apple's article on booting from external:

Use an external storage device as a Mac startup disk - Apple Support

If you have an external storage device, you can set it up as a Mac startup disk.

support.apple.com

 

[Alwyn]

Thanks Jake. I note that I should have beenable to install High Sierra 10.13.6 to an APFS formatted drive.

 

[Alwyn]

Did you create a Bootable USB Installer to a USB flash (thumb) drive?

No I downloaded the macOS to the Applications folder,clicked install and at the prompt installed it on a 1tb external SSD.

 

[Rod]

Alwyn, what you've done will give you an Operating System (OS) capable of booting the iMac, albeit slowly, assuming that it's just the HD that's crashed and not some other essential hardware element but it doesn't address the data on the Macintosh HD. If the Macintosh HD becomes seriously corrupted you may not be able to access it's data even booted from a different source.

A Bootable Installer on the other hand offers one other advantage over an OS on an external source in that it allows you to not only boot a device and access Disk Utility for repairs but also instal a fresh version of the OS.

Alternatively a bootable clone will not only allow you to boot the iMac in the case of internal HD failure but allow you to access all the cloned data and or transfer it to another computer.

For example my wifes MBP HD crashed, I had a CCC bootable clone of her drive, I installed a new blank SSD into the device, booted from the clone and used CCC to clone itself onto the blank SSD. The result was a duplicate internal HD of the old HDD and my wife was back up and running with everything the same.

So, that would be my choice for the maximum flexibility and safety.