If you read my previous post about how to format an external hard drive, you know that I bought a 2TB Seagate Expansion external drive and managed to create two partitions on the disk — one for Mac backup purposes, and the other for personal use.

In this article, I’m going to show you how to backup your Mac data to an external drive. You should backup your Mac on a regular basis, especially if you’re planning to perform macOS updates.

A hard drive can be used on any type of computer - PC or Mac. But in order for the computer and drive to talk to one another, the drive has to be formatted. This article explains. Seagate branded external drives come preformatted, some for PCs, some for Macs, and some of them have special utilities. Format an external hard drive for Mac. How to Format External Hard Drive for Mac. If you are trying to format Mac external hard drive, you can go over the process step by step: Step 1. Connect your hard drive to your Mac. Open Finder and choose 'Applications Utilities Disk Utility' to launch the app on your Mac. Once you open the Disk Utility app, you can see all the drives on your Mac are listed.

I did this several weeks ago while preparing my MacBook Pro for the High Sierra update. You may also be interested in taking a look at the issues I encountered during that process just in case you also want to upgrade your Mac to the latest macOS.

How To Format External Hard Drive For Mac Without Losing Data

Please note that the backup tool that I used is Time Machine, a built-in app provided by Apple. If you want to backup your Mac data without using Time Machine, there are also alternatives worth considering.

Where is Time Machine on Mac?

As I said, Time Machine is a built-in app within macOS ever since OS X 10.5. To find it, click on the Apple logo on the top left corner of your screen, then select System Preferences.

In the Preferences Pane, you’ll see the app located between “Date & Time” and “Accessibility”.

What does Time Machine Backup?

Time Machine is definitely the easiest way to backup Mac. In addition, the app is created and recommended by Apple. Once you have a timely backup, it’s incredibly easy to restore all or part of your data in case of accidental deletion or a hard drive crash.

So, what kind of data does Time Machine backup? Everything! Photos, videos, documents, applications, system files, accounts, preferences, messages, you name it: They all can be backed up by Time Machine. You can then restore your data from a Time Machine snapshot. To do so, first open Finder, then Applications, and click on Time Machine to continue.

Be aware that the recovery process can be only be conducted when your Mac is bootable.

A Step-by-Step Guide to Backing up Mac to an External Hard Drive

Note: the screenshots below are taken based on macOS 10.12.5 Sierra. If your Mac has High Sierra or an older version, differences may exist, but the process should look similar to what’s displayed below.

Step 1: Connect your external hard drive.

First, use the USB cable (or USC-C cable if you’re on a newest Mac model with Thunderbolt 3 ports) that comes with your external drive to connect that drive to your Mac. Once the disk icon shows up on your desktop (if it doesn’t, open Finder > Preferences > General, and here make sure you’ve checked “External disks” to let them show on the desktop), move on to Step 2.

Step 2: Select the disk for backup.

Now open Time Machine (I tell you how above) and select the disk you want to use. I have partitioned my Seagate drive into two new volumes, “Backup” and “Personal Use”, as you see from the screenshot. I chose “Backup”.

Step 3: Confirm backup (optional).

If you have used another disk for backup before, Time Machine will ask you whether you want to stop backing up to the previous disk and use the new one instead. It’s up to you. I selected “Replace”.

Step 4: Wait until the process is complete.

Now Time Machine will start to backup all your data. The progress bar gives you an estimate of how much time is left before the backup is complete. I found it a bit inaccurate: Initially, it said “About 5 hours remaining”, but it only took two hours to finish. It’s worth noting that the remaining time may vary from case to case depending on the write speed of your external hard drive.

It says I have to wait 5 hours

After about an hour and a half, it says only 15 minutes remaining

How To Format External Hard Drive For Mac Backup

Step 5: Eject your external drive and unplug it.

When the backup procedure is completed, don’t rush to disconnect your device as this could cause potential disk problems. Instead, go back to the main desktop, locate the volume that your external hard drive represents, right-click and select Eject. Then, you can safely unplug the device and put it in a safe place.

One More Thing

Like any other hardware device, an external hard drive will fail sooner or later. It is advisable to make a copy of the data on your external drive — as they say, a “backup of your backups”! One good option is to use cloud storage services. I now use IDrive (read our full review here), and I really like it because the app is so easy to use, and it also allows me to back up my Facebook albums and photos automatically. Backblaze and Carbonite are also popular options in the market, though I have yet to give them a try.

I hope you find this tutorial helpful. I can’t emphasize enough the importance of data backup these days, especially when my mid-2012 MacBook hard drive died all of a sudden. I’ve also seen cases where my friend’s computer and hard drive failed. You can imagine their desperation. Without a proper backup, it’s really hard to restore data. Although you could try a third-party recovery program like Prosoft Data Rescue and Stellar Mac Data Recovery, chances are they won’t get all your lost data back.

Anyway, the main takeaway I want you to have from this article is this: Backup your Mac with Time Machine and create a second or third copy of those backups if you can.