Time Machine Backup External Drive Title Image

The last thing you want as you’re showing your best friend that crazy holiday photo.

Is to get that fateful notice that says you’ve a fatal error on your Mac’s drive.

You can reinstall everything. And get back all the stuff you have on your Mac.

Easily. As long as you have a backup.

Time Machine backup external drive and have a copy of your drive.

Follow the steps below and find out how to backup your Mac’s internal drive.

Or an external drive to another drive with Time Machine.

You’ll also find photos to help you along.

First Have Your Backup Drive Ready For Time Machine

Let me explain.

Time Machine will only backup to a storage device.

And that device can be an SSD (Solid State Drive) Or hard drive. Even a partition on a large enough drive or a large enough flash drive. If it’s formatted as APFS or Mac OS Extended (Journaled) file system.

With the Mac OS Ventura file system, setting your drive up for Time Machine formats your drive ready for Time Machine.

In earlier Mac OS releases before you started you needed to check. Check if the drive you were using for your Time Machine backup was formatted in a way that Time Machine and your Mac’s operating system understood.

In MacOS Big Sur and earlier releases Time Machine only backed up to Mac OS Extended (also known as HFS+) only.

Bear that in mind if you’re backing up on a Mac that’s running MacOS Catalina or earlier. Because that Mac won’t backup to drives. Or read a backup on a drive formatted as APFS.

And so depending on the format of your hard drive, or Solid State drive. You may need to use software on your Mac called Disk Utility to format it first.

Don’t know how to check the format of your drive? Quickly read this document ‘ How To Check Format Of External Hard Drive On Mac‘ on the site.

And if you need to format your drive. You can learn how here at this ‘Format External Hard Drive For Mac Time Machine‘ post.

Take 5 minutes to do that and head back here afterwards.

All set?


Now plug in your external backup drive and get yourself ready to backup with Time Machine.

7 Steps To Backup Your Internal Drive To A Backup Disk With Time Machine

1. Start Up The Time Machine Software On Your Mac.

The easiest way to do this is to do a spotlight search.  Click on the spotlight search icon at the top of your Mac’s desktop screen.

Spotlight Search Symbol
Spotlight Search Symbol

Type in the words ‘system preferences’.

That searches your Mac. Or MacBook for the system preferences program.  And on that screen you’ll see what you’re looking for – Time Machine.

Spotlight Search System Preferences
Spotlight Search System Preferences

2. Click On Time Machine.

Click on the Time Machine icon in System Preferences and your Mac’s Time Machine software starts up.

Now you’ll see your first Time Machine window.

Samsung T7 !st Time Machine Window
Samsung T7 !st Time Machine Window

On the left hand side of the screen under the Time Machine icon you’ll see a check box.  Check this box to choose automatic backups.

Then your Mac will back up whenever you plug your drive in.

On the bottom of your Time Machine window you’ll see another check box. This check box shows the Time machine icon at the top of your Mac’s desktop, in your menu bar. It’s useful to put a check in this box.

You’ll can click the icon while your Mac or MacBook Pro is backing up. And check on how your backup is doing.

Now, click the button on the right hand side of the screen ‘Select Backup Disk…’

3. Time Machine Select Backup Disk Window.

In this popup window you’ll find all the external drives physically plugged into your Mac

Pick on the name of your external hard disk. The drive you want Time Machine to backup to.

Look at the picture below

Samsung T7 Time Machine Choose Drive
Samsung T7 Time Machine Choose Drive

You’ll see the drive I’m using is called SamsungT7.

Yours will be called whatever you named it when you formatted it.

Click to pick your backup destination drive for Time Machine. And you’ll see it highlighted in the list.

Then decide if you want to encrypt your backup.

There’s a check box at the bottom of this Time Machine pop up window.

If you decide to encrypt your backups. Then you’ll next see a prompt to put in a password.

Take care of this password. Record it somewhere safe. You’ll need it to get to your backup. And if you forget this password you’ve lost your backup.

4. Click ‘Use Disk’

And your Mac will now use your external HDD to back up to.

Samsung T7 External Drive Picked
Samsung T7 External Drive Picked

You’ll notice some useful information just under your drive’s name.

The size of your USB drive.

The oldest backup.

Your latest Backup.

When your Mac is due to take the next backup.

And you find out here what Time machine keeps.

Time Machine keeps local snapshots when you have space.

Your Mac will take hourly backups – a backup each hour for the last 24 hours. This assumes you’ve plugged your backup drive in and it’s working.

Time Machine will keep a daily backups for a month.

And weekly backup until your backup drive runs out of space.

Then Time Machine deletes your oldest backup. This creates space on your backup drive to make way for the latest backups.

It’s worth knowing something.

Time Machine takes an incremental backup. And after your initial backup your backups are incremental forever. 

What does that mean?

Time machine backs up only your changes. And when you’re ready to restore it recreates your Mac back to the time in point you’ve chosen from the backup.

Or everything if you use your Mac’s Migration Assistant to restore.

5. Click On The ‘Options’ Button.

You won’t always need to do this but it’s worth knowing what’s there.

Samsung T7 Options Pop Up
Samsung T7 Options Pop Up

This Time Machine window allows you to exclude folders from your drive’s backup.

You can click on the plus sign and add the folders you want to exclude.

Or check the box to exclude your Mac’s system files and your applications.

If you make no changes here then Time Machine will back up everything on your internal drive.

You’ll also see ready checked the box ‘Back up while on battery power’. This means that you’ll need to have your Mac plugged into external power to do your backup.

This is a good thing as the last thing you want is for your Mac to run out of battery power part way through your backup. Ruining your backup.

Click on the ‘Save’ button if you’ve made any changes or ‘Cancel’ if not.

6. Hurray You’ve Set Up Your Mac Backup To Your Drive.

Your initial backup could take some time depending on how much you have to backup. And how fast your external backup drive is.

Backup’s after that will be much quicker. As your Mac will back up what’s changed since the last backup.

7. How To Check On The Progress Of Your TM Backup.

When you checked the box to show the Time Machine icon at the top of your desktop this is how to use it.

Click on the Time Machine icon.

Samsung T7 Check Progress Of Time Machine Backup
Samsung T7 Check Progress Of Time Machine Backup

You’ll then see what Time Machine has already backed up to your external drive. And what’s left to backup.

You can also click on this icon to find out when your backup’s finished.

There are a couple of other ways.

Your drive icon on your desktop may turn green (depending on the version of MacOS you’re running).

You may get a message telling you your Backup is Complete.

Samsung T7 Time Machine Backup Complete
Samsung T7 Time Machine Backup Complete

Remember To Eject When Your Backup Is Done

Your Mac holds all sorts of information in its memory while your drive’s connected and backing up.

And it’s important that you plug out your backup drive the right way so you won’t ruin your backup.

Samsung T7 Eject Drive
Samsung T7 Eject Drive

Right click on your drive’s icon on your desktop. And pick Eject.

That way your Mac will write all that it needs from its memory to your drive. When your drive icon disappears from your desktop.

And any activity light on your backup drive goes out. Or keeps steady or whatever is appropriate for your drive.

Then you can plug out your USB cable. And put your drive safely away till the next time you want to backup.

The Next Time Machine Backup To Your Drive

When you’re ready to do your next backup. Your Mac will remember your backup disk.

Plug it in. Plug in your Mac to external power. And that’s all you have to do.

Click on the Time Machine icon at the top of your desktop to check on the progress of your backup.

Be sure to Eject your drive properly when your backup is done.

How To Backup External Drives With Time Machine

Is easy to set up.

First have both drives plugged into your Mac.

2 External Drives Connected To Mac
2 External Drives Connected To Mac

They both should show up on your desktop. Though they may not show side to side like in the photo above.

If your Mac has only two USB C ports then you’ll need something to help.

Satechi On Desk

A USB C Hub Like The Satechi Aluminum Multiport Adaptor. Check The Write Up Here.

A USB hub allows you to plug your Mac into power and plug in more USB drives.

You can read an article on this site about it at the link above.

When you’ve both external drives connected to your Mac. Then walk your way through steps 1 through 4 above to pick the one you’re going to use as your backup drive.

At step 5 click on the ‘Options’ button.

Samsung T7 External Drive Pick Options
Samsung T7 External Drive Pick Options

Adding Your Plugged In Drive To Your Backup

Now you need to understand.

That your Mac automatically excludes external drives from your Time Machine backup. And that means you’re going to have to change that.

Time Machine 2 External Drives Options
Time Machine Option Window for 2 External Drives

When you plug your second drive in.

On the Time Machine options popup you’ll see your second drive. The one you want backed up.

You’ll see in the photo the greyed out Samsung T7 drive (the one I am backing up to).

And the arrow in the photo shows a Seagate Desktop drive (the one I want to backup with Time Machine).

Now click on the drive you want Time Machine to backup.

Then click on the minus sign and take your second drive off the excluded list. And then Time Machine will include it in the backup.

Yes, I know, it’s a little hard to wrap your head around it.

But your second drive was on the list of things excluded from your backup. Click on the drive and click minus. And now it’s included in the backup.

Now Time Machine will back up everything. Your Mac’s internal drives and your second drive.

Only Want Your Plugged In Drive Backed Up?

If you ONLY want the files of your external drive backed up by Time Machine. Then you’ll need to exclude the contents of your Mac.

On the options screen as well as clicking minus to take your external drive off the list.

You also click plus to include your Mac’s internal files on the excluded list.

By starting at the top level / folder.

Then you’ll be doing an external drive to drive backup using Time Machine.

When you’ve finished your changes click ‘Save’.

Once set up your Mac will remember what you’ve set up. And the next time those drives are plugged in for backup It’ll be how you set it up.

At any time, you can go into the Time Machine option screen and change it.

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