How to install Catalina (with all data) onto new SSD with Time Machine?

I apologise for the ignorance on this issue. But thank you in advance for replies.

Well, it is a complex process mostly because there are several ways to do this, each with their own pros and cons with two basic strategies.

• You can install Catalina, then Migrate from your backup. This is always my preferred method as it tends to clean up things a little bit over Restoring.
• You can Restore from your Time Machine backup as long as the new drive is at least as big as the original drive. You should end up with exactly what you had.

Format the new drive

This can be done from Recovery, however you get there.

In Disk Utility,

1. Select "Show All Devices" from the View button in the toolbar.
2. Select the SSD device from the list. It should be indicated by make, model, size or some combination of that.
3. Click the Erase button
4. Set partition map to GUID
5. Set format to APFS (you won't be able to choose APFS until you set GUID in previous step).
6. Pick a name for your drive. You don't have to use Macintosh HD.
7. Click Apply or Erase or whatever the default button says.
8. Quit Disk Utility.

Recovery Options:

• Internet Recovery (cmd-opt-R). Boots up from Apple's servers, so it takes a while and a good internet connection is necessary.
• Download Catalina from App Store and create a bootable installer. You'll need a USB Flash drive of at least 8GB size.
• Boot from the Time Machine backup. The Time Machine backup must have been created on an external drive directly connected to the Mac via USB. If you backed up over the network (not USB), then I don't think it creates the recovery boot option.

To boot up the Mac from another source, hold down the Option key on restart. You will be presented with all bootable options. You should see the Catalina Installer for a bootable USB and EFI Boot for a Time Machine backup. Arrow over to the desired boot source and hit Enter.

Along with installing and Migrating, I think the bootable installer is the best way to go as you will have managed to download the Catalina installer instead of hoping that it will download over Internet Recovery. But, if you are just going to Restore from the TM backup, this is not necessary.

In all of these options, all drives must be directly connected to the Mac, not through a hub.

Restoring.

• Install and Migrate: Once the OS is installed, restart and go through Startup Assistant. When it asks if you want to transfer information, use the option to Migrate from a Time Machine backup. You can choose which users you migrate. Applications and other configurations can be migrated, also. You probably want to check each category to restore. That will make it as similar to your current install as possible and leave little to configure afterwards.
• Restore from Time Machine. Boot from Time Machine backup disk and use the Restore from Time Machine Backup option in the Utilities. If you can't boot from the TM backup drive, you can still just choose Restore from the Utilities screen.
• Install and Migrate after Startup Assistant. You would need to create a new user on the drive in the Startup Assistant. Make sure it is not the same name as any user you will migrate later using the Migration Assistant. After getting set up, I just use this account for admin tasks.
  • You would then use Migration Assistant after setting up.

Here are some Apple references:

How to reinstall macOS from macOS Recovery - Apple Support

How to create a bootable installer for macOS - Apple Support

How to erase a disk for Mac - Apple Support

Restore your Mac from a backup - Apple Support

You can't use the same new SSD to be both your Time Machine backup and your new system drive!

You should definitely do a Time Machine backup onto a different drive, to be safe.

You could clone your present drive to the new SSD - using a program like SuperDuper! or Carbon Copy Cloner.

The way I recommend to proceed is the following:

Make sure you have good backups

Install a clean system onto the SSD. You can do this from Recovery mode, but it is better to first create an installer on a usb thumb drive and use this.

a) Create an installer on a thumb drive. Instructions for this are widely available.

(for example, here: https://support.apple.com/sl-si/HT201372)

b) Start from the installer drive by holding the Option key at startup. Select the new SSD and install

c) When the installer asks you, elect to migrate content from "another mac, disk or time machine backup". Select your backup.

NOTE: I recommend you migrate only the user accounts, and then install fresh copies of applications; do NOT migrate "settings" or "other files". This is a good way to let go of old stuff that may have been installed for years, which you don't even know you have, and may cause problems down the line.