One of my frequent recommendations is that you purchase an external hard drive for your backups. Backing up to an external drive is probably the most important first step in getting an overall backup strategy in place.
The inevitable question is just which external drive to get.
The problem, of course, is that the answer keeps changing. Technology evolves, and as a result, so does my recommendation.
Let me give you a few guidelines, and then a few current (as of this writing) examples.
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External drive capacity
It’s pretty easy to say you can never have too much capacity. Bigger is better.
Of course, more capacity also means spending more money.
The rule of thumb I like to use is this: get an external drive that is at least three times as large as the amount of data you expect to back up.
For example, one of my Windows machines has a roughly 127GB (gigabyte) drive, of which around 44GB are used.
Thus, I would recommend a capacity of at least three times 44GB, or around 132GB. That would be enough to hold two complete and compressed full-image backups, along with overhead information such as recovery partitions, and a healthy collection of incremental backups as well.
As I said, that’s a bare minimum, and there are certainly situations where it could end up not being enough, depending on how you configure your backups. If you want extra safety and breathing room, double or even triple my recommendation.
In most cases, the good news here is that your back-up requirements – even after tripling my recommendation – will likely be smaller than the average external hard-drive size currently available.
External drive technology
There are, naturally, several different types of external drives. Connection methods and even power options vary. Some choices are easy; some depend at least a little on your personal setup.
There’s simply no reason not to ensure your new drive comes with a USB3 interface, even if your computer doesn’t support it.
If your computer does support USB3 (usually indicated by the plastic in the USB connector being blue), backups will be faster. If your computer doesn’t support USB3, that’s okay, it’s backwards compatible, and will operate at the slower USB2 speed.
Someday, when you get a new computer it will, in all likelihood, have a USB3 interface. You’ll have an external drive all ready to take advantage of it.
In my opinion, SSDs, or Solid State Disks (which use high-quality flash memory instead of rotating magnetic platters), aren’t appropriate for back-up purposes. I have two reasons:
- Expense: though prices are coming down, SSDs are still more expensive than traditional hard disks of the same size.
- Longevity: the lifespan of magnetic media is well understood. Once written, it stays written for a long time. Even in the worst circumstances, data can typically be recovered. The same can’t be said for SSDs.
The primary feature of SSDs – speed – is unnecessary. The speed advantage of an SSD is about reading data, and backups are all about writing.
What I didn’t mention was ‘wearing out’. Flash memory does wear out the more you write to it, but SSDs have a longer useable lifespan than their cheaper thumb-drive counterparts, and backups don’t write as much to the drive as you might think. Yes, they write a copy of everything (or everything that’s changed) each time you back up, but that’s nothing compared to the constant use that SSDs are under – and are designed to handle – when used as the primary disk drive of a computer.
There’s nothing inherently wrong with using an SSD as a backup drive, as long as it is a true HD-replacement quality drive, and not a cheap thumb drive. I just wouldn’t recommend it.
There are two approaches to powering an external drive.
- No additional connection: the drive is powered entirely by the USB interface.
- A separate external power supply.
USB-powered drives are typically smaller, more portable, and slower. Drives with external power supplies are typically physically larger, with more capacity, and are able to transfer data more quickly.
I use both. The backup drive with my laptop is small, portable, and easy to travel with. Backup drives attached to my desktop machines are typically externally powered.
Physical size: if you care, you can narrow your selection based on physical drive size – for example, a 2.5 inch drive versus a 3.5 – but in the long run, that choice will probably be made for you based on the choices you made above. USB-powered portable drives are generally small, and drives with external power will be physically larger.
Rotation speed: I never pay attention to this for external drives, particularly back-up drives. The USB interface speed will be the limiting factor, so focus instead on getting USB3, if you can. If you’re on USB2, the speed of a faster drive is wasted.
Specifics: what external drive to get
As I said when I started, drives are changing constantly. But with that in mind, here are a couple of drives that I can recommend today – where “today” is July, 2018.1
This is the drive I’d purchase if I needed to today. They’re available in capacities from 1 to 4TB (terabyte – that’s a thousand gigabytes). I were to buy one, I’d opt for the largest simply because you can never have enough disk space. In fact, that’s one of the reasons I’ve not needed to purchase one recently, as my previous purchases were always of the larger capacity available at the time.
Externally powered: Western Digital My Book Desktop External Hard Drive.
These are available in capacities from 3 to 20TB.
Again, if I needed an external drive this is the one I’d buy. The maximum capacity is difficult to resist. Like I said, you can’t have too much disk space.
But naturally, choose what your budget will allow, as long as it meets the minimum capacity requirements I laid out earlier.
Opinions are easy to come by
Hard disks are a very difficult category of product to recommend. The problem is that the industry is cyclic: a great hard-drive manufacturer five years ago might be horrible today.
Unfortunately, that’s true for all the major hard-drive manufacturers: their quality appears to come and go in waves. Fortunately, there’s usually at least one cresting while another is at its low point.
Previously I’d recommended Seagate drives, and that’s what most of my current (older) external drives are. In researching this update Western Digital seems to be getting slightly better reviews today. By the time you read this that can change. In addition, others may feel differently, either based on their own experience, whether current or not, or because the market has changed.
So, when you’re shopping for an external hard drive, pay attention not only to the reviews you might read, but also to the dates of those reviews.