Cloning Startup disk to new internal hard drive High Sierra

+1 for Carbon Copy Cloner.

Avoid Disk Utility....it is a joke of an app although you must use it to erase drives & run First Aid scans on the file system since you really have no choice. And it can be used to create small DMG archives, but otherwise it is best to avoid it except for checking the Free storage space on a drive (especially an APFS volume).

Anthony ÓDoibhailein wrote:

Does this then require me to format the new drive first before then cloning the older one back on to it? Or is the formatting done at some part of the cloning process in CCC? Just so that I am sure.

You must format (aka "erase" in macOS parlance) the drive with the file system you want for it. All CCC does is basically copy files from one location to another location and for a bootable drive it can recreate the necessary boot files & recovery partition as well. CCC does not actually make an identical clone, but functionally identical copy.

It should be possible to convert the HFS+ volume to APFS by using Disk Utility without needing to erase the drive or destroying the data (always have a good backup just to be safe). This option exists on one of Disk Utilities menus. While upgrading/installing macOS, the installer can do the conversion automatically, but you may need to boot from a macOS to do it yourself (USB or Recovery Mode).

I should add that these are HDD and not SSD drives.

For High Sierra, you can use either HFS+ or APFS on the boot drive. If the boot drive is a Hard Drive, then it is best to have it formatted as HFS+ (aka MacOS Extended (Journaled) ) since the APFS file system can cause the Hard Drive to work much harder.

If you have an SSD, then you can use either file system, but APFS was made specifically for SSDs. Plus the APFS file system has some special features to minimize wear on the SSD and also to save space as well. In addition it is possible to create other APFS volumes within the hidden Container which act like partitions (aka dividers), but do not need to restrict the size.

macOS 10.15+ requires the boot drive to be using the APFS file system since it utilizes those features (especially the multiple APFS volumes sharing the same storage pool within the hidden APFS Container).

The way I test an OS before updating my internal is to clone my internal to an external drive using Carbon Copy Cloner, then boot from the external and update that drive to the next OS and test.

+2 for CCC - as already said, don't use Disk Utility.

Less issues if you start with the correct format which in this case is APFS. I do not like letting any system automatically change any formats. This process prevents any possible issues. Does not take very long to make a bootable drive using CCC.

Anthony ÓDoibhailein wrote:

Does Mojave specifically need to be on a APFS formatted rive? Just trying to work out why I am getting that error message.

Mojave can be cloned with CCC to MacOS Extended volume and used there OK, but Mojave updates do not work there.

Anthony ÓDoibhailein wrote:

You mention that it should be possible to convert the HDD to APFS using disk Utility without having to erase the drive or destroying the data. However the option to do this is greyed out in Dusk Utility menu so I'm not sure if this is due to the OS version (High sierra). I am booting up from the existing drive and can manage the other new drive which is an internal drive directly.

You may not be selecting the correct item on the left pane of Disk Utility. macOS is very particular sometimes. It has been a few years since I last tried to convert an HFS+ drive/volume to APFS.

If you have Filevault enabled, then that will need to be unlocked first. Just use Disk Utility to mount the locked volume.

Does Mojave specifically need to be on a APFS formatted rive? Just trying to work out why I am getting that error message.

No. I see @Matti Haveri mentions that Mojave won't be able to update itself (never knew that), but that doesn't matter since the current macOS installer will have installed the most recent version of Mojave anyway.

Was your clone formatted to APFS when using CCC? Also if for some reason your drive is full then the upgrade may not work.

Use Carbon Copy Cloner. macOS compatibility:

https://bombich.com/download

I always use APFS with all SSD's so no OS conversions are required. I would do another clone but format to APFS then you can do the upgrade without issue.