Risk what? Your memories, your listening pleasure and all your hard work, stored on your Mac laptop and desktop.
It doesn't matter if your data is;
Work documents, legal documents or that video of grandma holding her first grandchild. You want to know you're not going to loose them forever.
This is where having an external hard drive fits in.
For Those of You Who Have to Know Now
I know, some you who visit will want to cut to the chase,
what is the best external hard drive for Mac?
Those who are happy to see the complete list just scroll past.
The top pick hard drive is ...
WD Elements Portable Hard Drive
Want to find out why? Stick with me and keep reading …
For Those of You Who Want to See the Complete List
You're nearly there. Here is a morsel of why before the tasty meal of what.
How did we get to our top five best external drives?
Well, we looked at;
- Reliability - only those with solid reputations and happy users made the grade
- The best brand names - it's not a guarantee of reliability, though the best brands have a reputation to defend and they got to be the best by producing the best products they could
- Storage Capacity in relation to price is important, no one wants to over pay for mediocre. But when the protection of your data is what's important - then paying a few dollars extra is worth it
- Speed and Connectivity - yes, the drives need to perform, because who the hell wants to wait forever for their back up? Also it has to connect to Macs as that's what we're all about here. And should you want to all of the drives in this article can be used interchangeably between a Mac and a PC
- Aesthetics and Portability - well you are a Mac user if you’re here and no one buys a Mac who doesn't care about how their computer looks
Even if you don't say it out loud, you want something that looks good and works great, just like your Mac does.
In establishing our top 5 list.
There were three categories we looked at;
- the top portables
- the top SSD
- the top ruggedized external hard disk
As the categories covered the main focus areas we know you find important.
In the top five we have chosen the best representatives from all three areas.
Here is our top five pick.
What Is the Best External Hard Drives for Mac in 2018
You can Click on the images to check on the prices on Amazon
Let us take a spin around the five hard drives that warranted a special mention and much later on in this article we will provide a six step guide to help you choose the best external hard drive for you.
In the quick reviews below we tell you about the things you need to know
watch out for
and what is behind the why they are on the list.
Let's go ahead and explore the special five in a little more detail.
Number One : WD Elements Portable Hard Drive
The top pick best external hard drive for Mac is from Western Digital and it is also the best portable. The 2 TB capacity occupying the sweet spot for its backup capacity and price performance. A solid reliable work horse keeping that important data of yours safe.
WD Elements Portable Hard Drive
- Popular because it offers a competitive cost for the hard drive volume you have available for saving those important files
- Western Digital is a top brand name and the two year warranty offered is a plus.
- With very little effort you can connect the Elements hard drive to your Mac. What's not to like?
- What you see is what you get, there aren't many extras on this disk drive.
Flexible in that if you want you can partition this disk and use and interchange it on Macs, and PCs. A really fantastic drive to have around and with such a reasonable price tag you can see why it was chosen as the best external hard drive for Mac.
It always pays to have multiple backups just in case. It is one way that'll work to keep your data safe.
WD Elements Features
The Elements Portable Hard Drive is classed as a basic drive. This means that there is no integral backup software provided on the hard drive, password protection or encryption on the hard drive for your files.
No worry for us Mac users as Mac OS comes ready with Disk Utility software and Time Machine. They will get your hard drive set up on the Mac and backing up in no time.
You can even set up encryption for your files via Mac OS if you're particularly sensitive about your information.
WD Elements Reliability
The Western Digital Elements hard drive has been around on the market since 2013 and has many happy users. Feel free to click through to Amazon on the link above and check out the user reviews.
And of course the beauty of buying through Amazon is that should you be extremely unlucky and receive a dead on arrival unit. Amazon takes care of you and you can send it straight back for a replacement.
YouTube Video Covering the WD Elements
I thought you might enjoy this YouTube video covering the WD Elements.
Video Credit: AndroRat
Elements Storage Capacity
The drive itself sports several capacities, so if 2TB is too large for you then you can go smaller with the 1TB offering,
If 1 TB is too small then fill your boots with their 3TB or 4TB or the newly available 6TB hard drive. Though the 6TB drive is a desktop device and is not portable.
The Elements hard drive is a 5,400 RPM laptop style drive that will give you up to 110 mb/s data transfer speed. The hard drive will be a solid performer for storing every day files and your backups. If you are doing video editing or other high performance requiring application then this drive will not be for you.
Consider purchasing a Thunderbolt or a SSD external hard drive for performance.
The Western Digital Elements connects via USB 3.0 though it does have USB 2.0 compatibility for those older Macs.
If you have one of the new model Macs that comes with Thunderbolt USB-C ports. or indeed if you have a Mac with a USB 3.1 port.
The WD Elements Portable can be used on those Macs but you will need a USB 3.0 to USB 3.1 or Thunderbolt adaptor cable.
Plug the drive in, it will run at the speed of USB 3.0 but that may not be a concern for you, if you are only using this drive for backups or file storage.
After all Thunderbolt drives do run up more expensive.
Understand that you can simply plug in your newly unboxed Elements Portable hard drive and your Mac will recognize the drive. You will need to reformat the drive to Mac OS Extended (Journaled) file system. Something that only takes minutes and then you are ready to use the Elements Portable hard drive on Time Machine to backup.
Unsure of how to reformat a hard drive on your Mac then have a look at my article here on the site.
Convenient in that the Elements Portable drive is powered by the USB port and draws its power from that. This means that there is no need for an external power adaptor.
Just bear in mind that the larger capacities of the desktop Elements hard drives that are 4TB and above are provided with power adaptors as those drives do need external power.
Aesthetics and Portability
Plain black, the looks of the drive is not really designed to excite or impress anyone. On the other hand the color is practical and efficient. What the drive is all about is its size.
The drive itself is beautifully sized at 4.4 by 3.2 by 0.82 inches and at 5.28 ounces you can pop it in your briefcase or hold all. And even if you are not carrying it around it won't take up much desk space or cupboard space to store.
Western Digital offers 2 years limited warranty on this hard drive which is pretty reasonable for the industry and shows they have confidence in the reliability of their hard drives.
WD Elements Versus WD My Passport
We have written an article that is a head to head comparison between WD Elements and the WD My Passport drive also on the top ten list. If you are considering both drives you be interested in my article here.
Number Two: Toshiba Canvio Advance Portable Hard Drive
The Toshiba Canvio Advance has been included in our list for good reasons. This is an external hard drive that boasts 1TB in a nice compact and designed as one of the best portable external hard drives. With fun colors, NTFS out of the box, password protection for your data (on the premium models), shock protection and very reasonable data transfer speeds.
Toshiba Canvio Advance Portable Hard Drive
- Fun colors, Compact, portable and lightweight design
- Easy formatting for Mac users
- Shock protection. Password protection (password protection on premium model only)
- Good range of storage capacities
- Be wary of using the USB 2.0 compatibility feature on older Macs
The Toshiba Canvio Advance is a great choice for Mac users who wants safe reliable performance, good storage capacity, and relatively fast transfer speeds. It more than meets expectations for a portable hard drive at its price.
Canvio Advance Reliability
On the outside, simple yet sophisticated in design, but on the inside its features include shock protection via an internal shock sensor and ramp loading technology to help protect the hard drive from knocks and bumps along the way.
An excellent feature for a portable hard drive considering it's not a ruggedized drive.
But as with all laptop specification hard drives, we wouldn't rely on this too much and be mindful about dropping it one time too many.
The drive is proven in the field with many very happy users, take a look at the reviews on Amazon by clicking on the picture link above.
But if you do happen to get the odd rogue unit then this is a good reason to buy via Amazon, just return for a replacement.
Toshiba Canvio Storage Capacity
The justifiably popular Canvio Advance comes in several capacities 1Tb, 2TB and 3TB. Just choose the capacity you want.
YouTube Video Showing You The Advance in Action
Have a look at this video I found showing you the Toshiba Canvio Advance in action.
Video Credit: Toshiba TAEC
Even with its smaller physical size, its data transfer rate is not as slow as you may expect – about 136 Mb/s when you’re using the USB 3.0 interface.
If you’re looking for the best portable external hard drive, combining convenient size and weight with a big storage offering for your Mac, then this may well address your needs.
A USB 3.0 drive that uses the USB port to power the hard drive so there is no additional power adaptor to worry about. A nice benefit on a portable.
Similar to the WD Elements Portable, the Canvio can be used on a Mac with Thunderbolt ports. A USB 3.0 to Thunderbolt adaptor cable will be needed. Easy enough to purchase from Amazon.
The Canvio Connect will run at USB 3.0 speed as that is all it's capable of but this may not matter if you are using the hard drive for backup purposes and don't want to pay a premium for Thunderbolt performance you do not need.
NTFS out of the Box
The Canvio Advance will need to be reformatted to use on a Mac. Reformatted to Mac OS Extended (journaled) file system or indeed ExFAT if you would like to share this drive with a Windows PC...
If you reformat to Mac OS Extended (Journaled) file system then the drive is compatible with Time Machine for backups.
There are a few other things to be borne in mind with this drive read my full review to learn all.
Canvio Advance Aesthetics and Portability
This is a drive that sports four different 'piano finish' high gloss case colors, black, red, blue and white. So if you want to match it with other accessories for your Mac then you can.
Though the high gloss finish could get annoying as a bit of a finger print magnet.
The drive fits easily into a small bag or in the back pocket of your jeans with a size of;
- 1TB and 2TB - 4.3 by 3.1 by 0.55 inches
- 3TB - 4.3 by 3.1 by 0.77 inches
And is as lightweight as the other portables in its class at;
- 1TB and 2TB - 5.28 ounces
- 3TB - 7.4 ounces
The attractive design also makes it a worthy accessory to be flaunted beside your Mac.
Canvio Advance Warranty
Comes with 2 year limited warranty, which is competitive for a basic portable in the market.
Number Three : Seagate Expansion 1TB Portable Hard Drive
The Seagate Expansion 1 TB is a basic external hard drive at an affordable price. Seagate have been around in the market place and have sold thousands of these hard drives. This is a great choice for entry-level users, and is among the best portable external hard drives along with the WD Elements portable drive and the Canvio Advance.
Seagate Expansion Portable Hard Drive
- Competitively priced
- Nice range of storage capacities
- Mac and Windows compatible. The drive can be shared between a Mac and a PC if you wish for formatting or partitioning to ExFAT
- 1 year warranty only
If you’re looking for a basic portable external hard drive, then the Seagate Expansion is up there as another great choice! Thousands of happy users out in the market place and only pushed into third place by the length of its warranty.
The expansion of storage space for your Mac is definitely the best reason for buying the Seagate Expansion drive. You will find that it more than meets your needs for an entry level drive at an affordable price.
Seagate Expansion Reliability
With many happy Mac users this drive is has proven itself to be reliable with users. Unfortunately with all consumer hard drives there are the odd hard drives that are shipped out and prove to be dead on arrival. You'd have to be extremely unlucky to get a Seagate one but fear not, Amazon will see you right.
Seagate Portable Storage Capacity
The Seagate comes in 1TB, 2TB and 4TB sizes so you have a reasonable choice in hard disk capacities.
The Seagate drive similar to the portable drives reviewed has a 5,400 RPM drive internally, but performs well for this type of hard drive at a top speed of 120 Mbps.
The Seagate Expansion Portable is fitted with a USB 3.0 port similar to both the WD Elements and the Toshiba Canvio. And as each of those hard drives the Seagate is powered via the USB port so there is no need for an additional power adaptor.
This means that you can plug the hard drive in as you would a USB stick. And if it's your first time using the Seagate Portable Expansion for a Mac user you simply reformat to have the drive connected to Mac only or to share between Mac and Windows Computers.
Unsure how to do this no fear take a look at the article here.
Like both the WD Elements Portable and Toshiba Canvio there is no direct Thunderbolt connectivity. This is easily solved by the purchase of a USB 3.0 to Thunderbolt adaptor cable from Amazon.
Saves you the cost of a more expensive Thunderbolt drive, particularly if you do not need the performance offered by those hard drives.
Seagate Expansion Portable Aesthetics and Portability
Seagate isn’t known for its sleek product designs. This drive is in black with a stylish checked pattern on the top. If you're not worried about design you can be assured that Seagate's external hard drives are among the most functional and durable in the business.
With a small neat design in a 4.9 by 3.2 by 0.6 inch enclosure is for sure portable and capable of being taken with you. At 6.4 ounces for the 1TB drive, it’s a little heavier than the WD Elements and the Toshiba Canvio Advance, none the less it is very portable.
The Seagate Portable External Hard Drive's Warranty
One year limited warranty is offered on the Seagate Expansion Portable. This is less than the two year's offered on the WD Elements and the Toshiba Canvio Advance which is a little disappointing and helps push this drive into third place in our estimation.
Number Four : Samsung T5 Portable SSD
And now we take a step, no.
A long stride up from the basic drives that have made the top five best drive list to take a look at the best solid state drive.
What is a SSD - solid state drive?
They differ from the mechanical drives we have looked at so far because internally they have no moving parts. The data is stored electronically. There are no fan's to cool the drives and so they are silent in operation, more resistant to knocks and bumps and are typically lightning fast.
There is a price tag associated with these SSD drives, as you pay much more per GB of storage …
But they give you oh so much more.
The first of these drives for the best external SSD 2018 list is the T5 Portable from Samsung. A beautiful drive in many ways, with optional password protection and file encryption (see what we say on that below)
Samsung T5 Solid State Drive
- Good looking, reliable and easy to use - who wouldn't want one.
- Lightening fast disk speeds making those backup's super quick
- Keep an eye out, occasional deals could mean you get this baby at a bargain price
- Problems experienced with Samsung's Mac software provided on the drive
With its handsome good looks, striking performance, the Samsung T5 is one of the best SSDs for a Mac and is likely to delight you. Particularly if you are a professional needing fast hard drive performance, need to keep your data safe in the field and need a hard drive to keep up with your latest Mac.
Samsung T5 Reliability
Because this drive operates electronically, there is no worry about internal parts wearing out and failing as they do on a normal mechanical hard drive. The T5 has exceptional reliability with many very happy users. You can read what those users say by clicking on the picture link to Amazon above. The quality of this drive just shines through.
T5 Portable Storage Capacity
The Samsung T5 comes in 250 GB, 500 GB, 1TB and 2TB flavors and covers the capacity that most users of this drive would want. There is a price premium you pay for this class of drive but if you are in the video editing, photoshopping or audio editing professions then you'll love this drives speed and you won't care about the price.
YouTube Video on the Samsung T5
Why not take a look at this quick under one minute video on the Samsung T5.
Video Credit: Samsung
T5 External SSD Speed
With a Single USB-C (USB 3.1) connection - perfect for Thunderbolt 3 connectivity to the latest Macbooks. The drive's headline speed is advertised at 540 mb/s though you are unlikely to get quite that on the Mac.
The Samsung is also compatible with USB 3.0 for older Thunderbolt 2 ports you'll also get decent performance.
The Samsung is provided with a second cable to allow you to connect this drive from USB-C to USB A (USB 2.0).
Useful for connection to older Macs with USB 2.0 ports but beware, those Macs are unlikely to be able send the data out to the T5 at anywhere near the headline speed the drive is advertised at.
The existing internal hard drives being too slow.
Macbooks running an older laptop internal disk drive are going to be nowhere as fast as this little baby so you'll need to bear that in mind. You'll get the speed the older Mac can do plus all the other benefits of having a SSD drive - reliability and drop shock resistance.
The T5 drive comes preformatted in ExFAT which makes it read, writeable and interchangeable between with both Macs and PCs.
Unless you plan to share this SSD between a Mac and a PC we would recommend you reformat the T5 on your Mac, to Mac OS (Journaled) file system.
Then you'll be able to use the T5 with Time Machine.
Several Mac users have reported problems with the default ExFAT formatting. So just in case you may well be advised to reformat. It only takes a few minutes.
How to do that?
Read my article here on how to do this.
The Samsung T5 is supplied with a software app to make it easier to use on a Mac, (those running Mac OS X 10.9 and above) beware users have reported issues using this software, best to stick with the software provided on your Mac rather than install this software.
Simply reformat the drive using Disk Utility on your Mac and you'll be golden.
Password protection on the hard drive is optional through Samsung's Portable SSD software. This software installs drivers in your kernel. A forgotten password means no access to your data. As some Mac users have experienced problems using this software I'd suggest avoiding
The Samsung Portable's Aesthetics and Portability
The drive is a real beauty with an Aluminum metallic case colored between royal blue and navy blue for 250 GB and 500 GB versions and in metallic black for the 1 TB and 2 TB versions. It's also reportedly able to take a drop of up to six feet.
That's all very reassuring though we doubt we would want to drop a drive this pricey for fun to test that claim out.
If you wanted to take this little baby about with you then it couldn't be more convenient. With dimensions of 0.4 by 2.3 by 3 inches 1.6 ounces it gives my credit card a run for its money.
The T5's Warranty
Tip top and shows Samsung's confidence in this drive and reflect the many happy users. Three years Limited warranty is the quality warranty you would expect of this kind of external SSD drive.
Number Five : LaCie Rugged Thunderbolt External Hard Drive
And now we come to the best rugged external hard drive. We have picked this LaCie Thunderbolt hard drive not just for its sporty outdoor looking design.
It also has some of the best rugged features around to back up its throw away good looks, with Thunderbolt, USB 3.0 and Firewire options for hard drive connections, as well as hard disk drive and SSD drive options.
The tough orange brand is traditionally loved by photographers, video editing and audio editing Mac computer users.
LaCie Rugged Thunderbolt Hard Drive
- Quality, practical and tough. This drive ticks all the boxes
- Impressive range of storage sizes and connection options to your Mac
- Can be formatted to be both Mac and Windows compatible and share betweeen the two computers
- Not the most attractive hard drive of the group, but oh so practical
- Reports of more hard drive failures since the take over of LaCie by Seagate
If you want a take with you nearly anywhere hard drive then you wouldn't go far wrong with this drive. Proven in the field and popular with the go everywhere crowd. Take this little orange daemon with you and be proud.
Rugged Thunderbolt Reliability
The orange one sporting its IP-54 rating that offers water resistance, Drip resistance, shock resistance along with hardware encryption.
This hard drive has been a favorite amongst professionals needing a reliable hard drive to take out in the field where conditions aren't always conducive to using hard drives.
With many hundreds of happy users this is a hard drive that is proven out in the rough. Want to see what users on Amazon think? Easy just click on the text link above and it'll take you over to Amazon where you can have a look.
Though there have been reports of an uptick in hard drive failures since the company was taken over by Seagate, those failures are low in numbers.
LaCie Thunderbolt Storage Capacity
Your rugged portable hard drives comes with capacity options and drive type options.
- There are 1 TB, 2 TB USB 3.0 rugged external hard drives
- and 250 GB, 500 GB, 1TB rugged external SSD options.
Powered by the USB port on your Mac, there is no separate power adaptor to worry about. Just as well with a hard drive designed to go out into the field.
With up to 122 mb/s hard disk performance or if you choose to go for a solid state drive up to 387 mb/s SSD performance. There is plenty of choice in performance level and size of disk drive.
To connect this hard drive to your Mac there is an integrated Thunderbolt USB-C (USB 3.1) cable that plugs directly into your Mac's thunderbolt port. This cable is fully covered and is resistant to the elements and when not in use can be tidied away inside the LaCie's cover.
This cover allows the LaCie external hard drive to be IP54 rugged and resistant to the elements.
Once removed the cover also exposes the USB 3.0 port.
Which is only relevant for the hard drive models with USB C and USB 3.0 connections.
And LaCie has supplied you with a separate USB 3.0 cable for connectivity and backwards compatibility with USB 2.0.
There are even versions of this hard drive with Firewire ports for connectivity over Firewire. You'll need to check the models for the ports you want - Thunderbolt (USB C) and or USB 3.0. Some of the models offer up to three different ports one USB 3.0 port and two Firewire 800 ports and the hard drives can be daisy chained together.
The LaCie set up assistant software that comes with the hard drive, allows you to set up this drive for use on a Mac exclusively. Or you can format the drive to ExFAT if you wish to share and interchange data between a Mac and a Windows PC
Plenty of choice for you.
LaCie Aesthetics and Portability
The orange ruggedized outer casing is designed to resist drops and falls. It may not be the prettiest of hard drives or the sleekest. But then it isn't why you would buy a LaCie hard drive.
The casing is IP54 rated to resist dust and water being splashed onto the hard drive. The SSD's are tested to resist falls of up to 6.6 feet, the hard drives up to 4 feet. LaCie have also tested the drive for crush resistance by LaCie driving over the drive using a 1 ton car and the drives still worked. Impressive.
Size of 0.98 by 3.5 by 5.52 inches and weight of 0.882 pounds it is no doubt portable and begs to be taken with you.
Rugged Thunderbolt Warranty
The external mechanical hard disk based LaCie's have 2 years limited warranty. The SSD based external drives come with 3 year's limited warranty.
Wrapping Up on the Final Verdict
Your choice in a Mac compatible external hard drive depends on several factors, from your budget through to your need for storage capacity, features and connectivity to your Mac.
The WD 2TB Elements hard drive answers the question of what is the best external hard drive for Mac because of its price performance, range of capacities and because it more than performs as a use every day hard disk.
But really in a way all the external hard drives on the list are winners and the five quick reviews above are the ones that deserved a special mention.
And depending on what is important to you, good looks, range of colors, performance or sheer toughness then your pick of the bunch may differ. As they say - your mileage may vary!
If you're still not sure how to go about choosing, then we have a treat for you, read on and note the six steps to choosing the right external hard drive for you.
6 Steps to Choosing an External Drive. That Special Companion for Your Mac
I am guessing you love your Mac, what ever flavor it is, iMac to Macbook to Macbook Air and why not?
They are lovely machines, designed to be easy to use, and get along with but they are not particularly expandable.
Your Macs attractive design,
Thinner, smaller, lighter enclosures. Is exactly what you wanted. And what about the software programs you have on it.
Well they are not growing smaller neither will there be less of them over time.
The best selfies, HD video's, the wish to have documents with embedded pictures and video's not to mention most documentation is being provided on-line and you need to store your own copy … course you do.
Macs are designed to be … well a Mac
so you won't want to open up the back (you can't on some Macs) and dig around in the internals to upgrade the hard drive …
And god forbid the next software upgrade makes your Mac unusable, or the internal disks you have everything so carefully stored on fails … so what do you do?
You need options and alternatives.
Storing your data in the cloud is a good option, assuming you have the network bandwidth to get to it all should you have a failure.
But what if what you have stored is sensitive, pictures, company documents. Would you be concerned about anything up in the cloud should someone break in and get to it?
And there you have it, the argument to get yourself an external hard drive and depending on how crucial your data is then maybe two.
It's unfortunate, that consumer grade hard drives both internal and external have been known to fail, so if you really have got to have it, have it in several places and you won't be left crying or cursing that it's gone.
An external drive that is easy to use, that you can store away when you're not using it, or transport files between locations.
And now there are so many options in the way your little Mac companion drive looks, how handy it is to take with you and how much you can get on it. Now we get to the meat, the how, the process,
The 6 Steps to Choosing Your External Drive
1. What Mac do you have?
This is important because an older Mac may have a USB 2.0 interface. What's that?
The place you plug your external drive into.
The newest Macs will have thunderbolt connections. Wha?
It means that you have a much faster connection interface to your Mac.
A USB 2.0 port compared to a Thunderbolt port is a physically different connection. You may only need an cable adaptor or a compatible cable but it's worth checking.
If you have several Macs types and generations then you may be looking for something able to connect to them all.
What interfaces to they have? make a note.
2. Next, Have a think About your Main Reason for having an External Drive
Is it storage for those mega important files or
for saving games, apps and movies that can be downloaded again easily.
Are they work files? Customer files? Sensitive? Do you need a drive that supports password protection and encryption?
Are you planning to share your drive between a Mac and a PC? Then you need to make sure it is of a large enough capacity to store the files you want to share and you'll need to spend the short time needed to format the drive to ExFAT or have a ExFAT partition where you can interchange files.
Are you out and about on location? Are the sites you visit hard drive unfriendly? Dust, dirt and water can kill of your external drive super quick. Could it get knocked about? Then a ruggedized or a solid state hard drive may be just what you need.
Are your files large and numerous? HD video's, photographs so you need a drive with capacity and one that is quick.
3. Storage Capacity in Relation to Price
It's a universal truth that the larger the storage capacity, the higher the price.
If your external drive will be backing up several Macs then you'll need to tot up the storage capacity of them all and how many days/weeks of backup you want to store.
There is nothing wrong with taking a leaf out of the book of large corporates. They will have hard drives that does Monday's backup and use a different set for Tuesday's backup, alternating days in the week. So that if the worst happens they have options.
Is a 1 TB disk drive or a larger 4 TB+ needed?
If your total backup requirement is 2TB then it is best to get a hard drive that is at least that size for backup. You probably should really have a 3TB or larger hard drive so that you can store your backups and grow into the drive.
Could you consider 2 x 2 TB's spreading the backup file load and have alternating backup drives?
Ok so your armed with that knowledge what now?
Compare your favored hard drives against the storage capacity you have in mind.
4. Connectivity and Speed
External hard drives for Macs usually have USB 3.1 or 3.0 interface with backwards compatibility with USB 2.0 interface for using with older Mac models.
That's how you physically connect. What else?
A number of external hard drives now take their power from the USB port on the Mac itself. This has implications for older Macs.
Macs are very picky about how much power external devices take and not all manufacturers have stuck as strictly to the USB 2.0 specification as Apple Inc. You may find those drives won't power up at all or consistently on your Macs USB 2.0 port so check.
Check that other users haven't experienced that problem.
you many not want a physical connection to the hard drive at all. You may want to perform backups wirelessly and automatically over Wi-Fi. In that case you'll be looking at a network connected device.
You may also want a drive that can be connected to and perhaps shared with your other household devices, such as to your game consoles, iPhones, printer, Windows based machines or even to your router. In that case you'll need to check your drive of choice is compatible with all those devices, get a hard drive that is big enough, partition it up and your good to go.
But if you’re looking at a drive for a professional application, or to connect to multiple devices across Wi-Fi then it pays to look for a drive speed that is up to that.
5. Reliability and Manufacturer Reputation and Warranty
The reliability of hard drives is generally determined by the manufacturer’s reputation for quality products, and on the length of the warranty offered. Why?
Lets face it a manufacturer is not going to offer a long warranty on hard drives that fail often.
Stick with the best manufacturing brands if you can, even if it costs a bit more. You've not been shy to spend on your Mac so it pays to make sure its external hard drive companion is of suitable quality.
For drives aimed at a consumer, the best warranty you'll see in the market place is a three year warranty offered by top manufacturers of the premium solid state drives and mechanical drives. A 2 year warranty is considered pretty good.
6. Handsome Looks and Portability
You have a Mac, you'll want something that looks good beside it right?
It's no accident that the best external hard drives for Macs have attractive designs as manufacturers that cater to the Mac market know well that a buyer of a Mac likes his kit to look good.
As for transporting your hard drive around,
size and weight in relation to disk capacity is important. Check that the dimensions and lightness of the drive suits your purpose.
Desktop external hard drives designed for use in the home are heavier and the technology assumes a stable surface.
Laptop class drives - as many of the portable external hard drives are, are largely aimed at the portable market place due to their smaller internal mechanisms. Some have mechanisms to resist shocks to the drive and drops to a certain extent. If you are looking at taking your hard drive around with you it will pay to get a quality case for it and look for a drive with features that make it more tolerant of what might happen to your drive in a pocket or bag.
Seagate Expansion and LaCie images by curtesy of Seagate Technologies